+Alexandre and Nicolas Hi Peter, Can you please Cc at91 maintainers next time? On Mon, 19 Jun 2017 09:44:23 +0200 Peter Rosin <peda@xxxxxxxxxx> wrote: > Hi! > > This series adds support for an 8-bit clut mode in the atmel-hlcdc > driver. > > I have now tested patch 1 with the below program (modeset.c > adapted from https://github.com/dvdhrm/docs/tree/master/drm-howto > to use an 8-bit mode). > > Since v2 I have also cleared up why the first 16 entries of the clut > was not working right. It was of course my own damn fault, and the > fix was in atmel_hlcdc_layer_write_clut function which called the > ...write_reg function which in turn added an extra offset of 16 > registers... > > Changes since v2: > > - Fix mapping to the clut registers. > > Changes since v1: > > - Move the clut update from atmel_hlcdc_crtc_mode_valid to > atmel_hlcdc_plane_atomic_update. > - Add default .gamma_set helper (drm_atomic_helper_legacy_gamma_set). > - Don't keep a spare copy of the clut, reuse gamma_store instead. > - Don't try to synchronize the legacy fb clut with the drm clut. > > As I said in v2, I have not added any .clut_offset to the overlay2 > layer of sama5d4, since the chip does not appear to have that layer. > I didn't do that to make it easier to work with the patch previously > sent to remove that layer, but I suspect bad things may happen to > sama5d4 users if they do not have that layer removed. > > Cheers, > peda > > modeset-pal.c (didn't update any comments, sorry) > ----------------8<--------------- > /* > * modeset - DRM Modesetting Example > * > * Written 2012 by David Herrmann <dh.herrmann@xxxxxxxxxxxxxx> > * Dedicated to the Public Domain. > */ > > /* > * DRM Modesetting Howto > * This document describes the DRM modesetting API. Before we can use the DRM > * API, we have to include xf86drm.h and xf86drmMode.h. Both are provided by > * libdrm which every major distribution ships by default. It has no other > * dependencies and is pretty small. > * > * Please ignore all forward-declarations of functions which are used later. I > * reordered the functions so you can read this document from top to bottom. If > * you reimplement it, you would probably reorder the functions to avoid all the > * nasty forward declarations. > * > * For easier reading, we ignore all memory-allocation errors of malloc() and > * friends here. However, we try to correctly handle all other kinds of errors > * that may occur. > * > * All functions and global variables are prefixed with "modeset_*" in this > * file. So it should be clear whether a function is a local helper or if it is > * provided by some external library. > */ > > #define _GNU_SOURCE > #include <errno.h> > #include <fcntl.h> > #include <stdbool.h> > #include <stdint.h> > #include <stdio.h> > #include <stdlib.h> > #include <string.h> > #include <sys/mman.h> > #include <time.h> > #include <unistd.h> > #include <xf86drm.h> > #include <xf86drmMode.h> > > struct modeset_dev; > static int modeset_find_crtc(int fd, drmModeRes *res, drmModeConnector *conn, > struct modeset_dev *dev); > static int modeset_create_fb(int fd, struct modeset_dev *dev); > static int modeset_setup_dev(int fd, drmModeRes *res, drmModeConnector *conn, > struct modeset_dev *dev); > static int modeset_open(int *out, const char *node); > static int modeset_prepare(int fd); > static void modeset_draw(int fd); > static void modeset_cleanup(int fd); > > /* > * When the linux kernel detects a graphics-card on your machine, it loads the > * correct device driver (located in kernel-tree at ./drivers/gpu/drm/<xy>) and > * provides two character-devices to control it. Udev (or whatever hotplugging > * application you use) will create them as: > * /dev/dri/card0 > * /dev/dri/controlID64 > * We only need the first one. You can hard-code this path into your application > * like we do here, but it is recommended to use libudev with real hotplugging > * and multi-seat support. However, this is beyond the scope of this document. > * Also note that if you have multiple graphics-cards, there may also be > * /dev/dri/card1, /dev/dri/card2, ... > * > * We simply use /dev/dri/card0 here but the user can specify another path on > * the command line. > * > * modeset_open(out, node): This small helper function opens the DRM device > * which is given as @node. The new fd is stored in @out on success. On failure, > * a negative error code is returned. > * After opening the file, we also check for the DRM_CAP_DUMB_BUFFER capability. > * If the driver supports this capability, we can create simple memory-mapped > * buffers without any driver-dependent code. As we want to avoid any radeon, > * nvidia, intel, etc. specific code, we depend on DUMB_BUFFERs here. > */ > > static int modeset_open(int *out, const char *node) > { > int fd, ret; > uint64_t has_dumb; > > fd = open(node, O_RDWR | O_CLOEXEC); > if (fd < 0) { > ret = -errno; > fprintf(stderr, "cannot open '%s': %m\n", node); > return ret; > } > > if (drmGetCap(fd, DRM_CAP_DUMB_BUFFER, &has_dumb) < 0 || > !has_dumb) { > fprintf(stderr, "drm device '%s' does not support dumb buffers\n", > node); > close(fd); > return -EOPNOTSUPP; > } > > *out = fd; > return 0; > } > > /* > * As a next step we need to find our available display devices. libdrm provides > * a drmModeRes structure that contains all the needed information. We can > * retrieve it via drmModeGetResources(fd) and free it via > * drmModeFreeResources(res) again. > * > * A physical connector on your graphics card is called a "connector". You can > * plug a monitor into it and control what is displayed. We are definitely > * interested in what connectors are currently used, so we simply iterate > * through the list of connectors and try to display a test-picture on each > * available monitor. > * However, this isn't as easy as it sounds. First, we need to check whether the > * connector is actually used (a monitor is plugged in and turned on). Then we > * need to find a CRTC that can control this connector. CRTCs are described > * later on. After that we create a framebuffer object. If we have all this, we > * can mmap() the framebuffer and draw a test-picture into it. Then we can tell > * the DRM device to show the framebuffer on the given CRTC with the selected > * connector. > * > * As we want to draw moving pictures on the framebuffer, we actually have to > * remember all these settings. Therefore, we create one "struct modeset_dev" > * object for each connector+crtc+framebuffer pair that we successfully > * initialized and push it into the global device-list. > * > * Each field of this structure is described when it is first used. But as a > * summary: > * "struct modeset_dev" contains: { > * - @next: points to the next device in the single-linked list > * > * - @width: width of our buffer object > * - @height: height of our buffer object > * - @stride: stride value of our buffer object > * - @size: size of the memory mapped buffer > * - @handle: a DRM handle to the buffer object that we can draw into > * - @map: pointer to the memory mapped buffer > * > * - @mode: the display mode that we want to use > * - @fb: a framebuffer handle with our buffer object as scanout buffer > * - @conn: the connector ID that we want to use with this buffer > * - @crtc: the crtc ID that we want to use with this connector > * - @saved_crtc: the configuration of the crtc before we changed it. We use it > * so we can restore the same mode when we exit. > * } > */ > > struct modeset_dev { > struct modeset_dev *next; > > uint32_t width; > uint32_t height; > uint32_t stride; > uint32_t size; > uint32_t handle; > uint8_t *map; > > drmModeModeInfo mode; > uint32_t fb; > uint32_t conn; > uint32_t crtc; > drmModeCrtc *saved_crtc; > }; > > static struct modeset_dev *modeset_list = NULL; > > /* > * So as next step we need to actually prepare all connectors that we find. We > * do this in this little helper function: > * > * modeset_prepare(fd): This helper function takes the DRM fd as argument and > * then simply retrieves the resource-info from the device. It then iterates > * through all connectors and calls other helper functions to initialize this > * connector (described later on). > * If the initialization was successful, we simply add this object as new device > * into the global modeset device list. > * > * The resource-structure contains a list of all connector-IDs. We use the > * helper function drmModeGetConnector() to retrieve more information on each > * connector. After we are done with it, we free it again with > * drmModeFreeConnector(). > * Our helper modeset_setup_dev() returns -ENOENT if the connector is currently > * unused and no monitor is plugged in. So we can ignore this connector. > */ > > static int modeset_prepare(int fd) > { > drmModeRes *res; > drmModeConnector *conn; > unsigned int i; > struct modeset_dev *dev; > int ret; > > /* retrieve resources */ > res = drmModeGetResources(fd); > if (!res) { > fprintf(stderr, "cannot retrieve DRM resources (%d): %m\n", > errno); > return -errno; > } > > /* iterate all connectors */ > for (i = 0; i < res->count_connectors; ++i) { > /* get information for each connector */ > conn = drmModeGetConnector(fd, res->connectors[i]); > if (!conn) { > fprintf(stderr, "cannot retrieve DRM connector %u:%u (%d): %m\n", > i, res->connectors[i], errno); > continue; > } > > /* create a device structure */ > dev = malloc(sizeof(*dev)); > memset(dev, 0, sizeof(*dev)); > dev->conn = conn->connector_id; > > /* call helper function to prepare this connector */ > ret = modeset_setup_dev(fd, res, conn, dev); > if (ret) { > if (ret != -ENOENT) { > errno = -ret; > fprintf(stderr, "cannot setup device for connector %u:%u (%d): %m\n", > i, res->connectors[i], errno); > } > free(dev); > drmModeFreeConnector(conn); > continue; > } > > /* free connector data and link device into global list */ > drmModeFreeConnector(conn); > dev->next = modeset_list; > modeset_list = dev; > } > > /* free resources again */ > drmModeFreeResources(res); > return 0; > } > > /* > * Now we dig deeper into setting up a single connector. As described earlier, > * we need to check several things first: > * * If the connector is currently unused, that is, no monitor is plugged in, > * then we can ignore it. > * * We have to find a suitable resolution and refresh-rate. All this is > * available in drmModeModeInfo structures saved for each crtc. We simply > * use the first mode that is available. This is always the mode with the > * highest resolution. > * A more sophisticated mode-selection should be done in real applications, > * though. > * * Then we need to find an CRTC that can drive this connector. A CRTC is an > * internal resource of each graphics-card. The number of CRTCs controls how > * many connectors can be controlled indepedently. That is, a graphics-cards > * may have more connectors than CRTCs, which means, not all monitors can be > * controlled independently. > * There is actually the possibility to control multiple connectors via a > * single CRTC if the monitors should display the same content. However, we > * do not make use of this here. > * So think of connectors as pipelines to the connected monitors and the > * CRTCs are the controllers that manage which data goes to which pipeline. > * If there are more pipelines than CRTCs, then we cannot control all of > * them at the same time. > * * We need to create a framebuffer for this connector. A framebuffer is a > * memory buffer that we can write XRGB32 data into. So we use this to > * render our graphics and then the CRTC can scan-out this data from the > * framebuffer onto the monitor. > */ > > static int modeset_setup_dev(int fd, drmModeRes *res, drmModeConnector *conn, > struct modeset_dev *dev) > { > int ret; > > /* check if a monitor is connected */ > if (conn->connection != DRM_MODE_CONNECTED) { > fprintf(stderr, "ignoring unused connector %u\n", > conn->connector_id); > return -ENOENT; > } > > /* check if there is at least one valid mode */ > if (conn->count_modes == 0) { > fprintf(stderr, "no valid mode for connector %u\n", > conn->connector_id); > return -EFAULT; > } > > /* copy the mode information into our device structure */ > memcpy(&dev->mode, &conn->modes[0], sizeof(dev->mode)); > dev->width = conn->modes[0].hdisplay; > dev->height = conn->modes[0].vdisplay; > fprintf(stderr, "mode for connector %u is %ux%u\n", > conn->connector_id, dev->width, dev->height); > > /* find a crtc for this connector */ > ret = modeset_find_crtc(fd, res, conn, dev); > if (ret) { > fprintf(stderr, "no valid crtc for connector %u\n", > conn->connector_id); > return ret; > } > > /* create a framebuffer for this CRTC */ > ret = modeset_create_fb(fd, dev); > if (ret) { > fprintf(stderr, "cannot create framebuffer for connector %u\n", > conn->connector_id); > return ret; > } > > return 0; > } > > /* > * modeset_find_crtc(fd, res, conn, dev): This small helper tries to find a > * suitable CRTC for the given connector. We have actually have to introduce one > * more DRM object to make this more clear: Encoders. > * Encoders help the CRTC to convert data from a framebuffer into the right > * format that can be used for the chosen connector. We do not have to > * understand any more of these conversions to make use of it. However, you must > * know that each connector has a limited list of encoders that it can use. And > * each encoder can only work with a limited list of CRTCs. So what we do is > * trying each encoder that is available and looking for a CRTC that this > * encoder can work with. If we find the first working combination, we are happy > * and write it into the @dev structure. > * But before iterating all available encoders, we first try the currently > * active encoder+crtc on a connector to avoid a full modeset. > * > * However, before we can use a CRTC we must make sure that no other device, > * that we setup previously, is already using this CRTC. Remember, we can only > * drive one connector per CRTC! So we simply iterate through the "modeset_list" > * of previously setup devices and check that this CRTC wasn't used before. > * Otherwise, we continue with the next CRTC/Encoder combination. > */ > > static int modeset_find_crtc(int fd, drmModeRes *res, drmModeConnector *conn, > struct modeset_dev *dev) > { > drmModeEncoder *enc; > unsigned int i, j; > int32_t crtc; > struct modeset_dev *iter; > > /* first try the currently conected encoder+crtc */ > if (conn->encoder_id) > enc = drmModeGetEncoder(fd, conn->encoder_id); > else > enc = NULL; > > if (enc) { > if (enc->crtc_id) { > crtc = enc->crtc_id; > for (iter = modeset_list; iter; iter = iter->next) { > if (iter->crtc == crtc) { > crtc = -1; > break; > } > } > > if (crtc >= 0) { > drmModeFreeEncoder(enc); > dev->crtc = crtc; > return 0; > } > } > > drmModeFreeEncoder(enc); > } > > /* If the connector is not currently bound to an encoder or if the > * encoder+crtc is already used by another connector (actually unlikely > * but lets be safe), iterate all other available encoders to find a > * matching CRTC. */ > for (i = 0; i < conn->count_encoders; ++i) { > enc = drmModeGetEncoder(fd, conn->encoders[i]); > if (!enc) { > fprintf(stderr, "cannot retrieve encoder %u:%u (%d): %m\n", > i, conn->encoders[i], errno); > continue; > } > > /* iterate all global CRTCs */ > for (j = 0; j < res->count_crtcs; ++j) { > /* check whether this CRTC works with the encoder */ > if (!(enc->possible_crtcs & (1 << j))) > continue; > > /* check that no other device already uses this CRTC */ > crtc = res->crtcs[j]; > for (iter = modeset_list; iter; iter = iter->next) { > if (iter->crtc == crtc) { > crtc = -1; > break; > } > } > > /* we have found a CRTC, so save it and return */ > if (crtc >= 0) { > drmModeFreeEncoder(enc); > dev->crtc = crtc; > return 0; > } > } > > drmModeFreeEncoder(enc); > } > > fprintf(stderr, "cannot find suitable CRTC for connector %u\n", > conn->connector_id); > return -ENOENT; > } > > /* > * modeset_create_fb(fd, dev): After we have found a crtc+connector+mode > * combination, we need to actually create a suitable framebuffer that we can > * use with it. There are actually two ways to do that: > * * We can create a so called "dumb buffer". This is a buffer that we can > * memory-map via mmap() and every driver supports this. We can use it for > * unaccelerated software rendering on the CPU. > * * We can use libgbm to create buffers available for hardware-acceleration. > * libgbm is an abstraction layer that creates these buffers for each > * available DRM driver. As there is no generic API for this, each driver > * provides its own way to create these buffers. > * We can then use such buffers to create OpenGL contexts with the mesa3D > * library. > * We use the first solution here as it is much simpler and doesn't require any > * external libraries. However, if you want to use hardware-acceleration via > * OpenGL, it is actually pretty easy to create such buffers with libgbm and > * libEGL. But this is beyond the scope of this document. > * > * So what we do is requesting a new dumb-buffer from the driver. We specify the > * same size as the current mode that we selected for the connector. > * Then we request the driver to prepare this buffer for memory mapping. After > * that we perform the actual mmap() call. So we can now access the framebuffer > * memory directly via the dev->map memory map. > */ > > static int modeset_create_fb(int fd, struct modeset_dev *dev) > { > struct drm_mode_create_dumb creq; > struct drm_mode_destroy_dumb dreq; > struct drm_mode_map_dumb mreq; > int ret; > > /* create dumb buffer */ > memset(&creq, 0, sizeof(creq)); > creq.width = dev->width; > creq.height = dev->height; > creq.bpp = 8; > ret = drmIoctl(fd, DRM_IOCTL_MODE_CREATE_DUMB, &creq); > if (ret < 0) { > fprintf(stderr, "cannot create dumb buffer (%d): %m\n", > errno); > return -errno; > } > dev->stride = creq.pitch; > dev->size = creq.size; > dev->handle = creq.handle; > > /* create framebuffer object for the dumb-buffer */ > ret = drmModeAddFB(fd, dev->width, dev->height, 8, 8, dev->stride, > dev->handle, &dev->fb); > if (ret) { > fprintf(stderr, "cannot create framebuffer (%d): %m\n", > errno); > ret = -errno; > goto err_destroy; > } > > /* prepare buffer for memory mapping */ > memset(&mreq, 0, sizeof(mreq)); > mreq.handle = dev->handle; > ret = drmIoctl(fd, DRM_IOCTL_MODE_MAP_DUMB, &mreq); > if (ret) { > fprintf(stderr, "cannot map dumb buffer (%d): %m\n", > errno); > ret = -errno; > goto err_fb; > } > > /* perform actual memory mapping */ > dev->map = mmap(0, dev->size, PROT_READ | PROT_WRITE, MAP_SHARED, > fd, mreq.offset); > if (dev->map == MAP_FAILED) { > fprintf(stderr, "cannot mmap dumb buffer (%d): %m\n", > errno); > ret = -errno; > goto err_fb; > } > > /* clear the framebuffer to 0 */ > memset(dev->map, 0, dev->size); > > return 0; > > err_fb: > drmModeRmFB(fd, dev->fb); > err_destroy: > memset(&dreq, 0, sizeof(dreq)); > dreq.handle = dev->handle; > drmIoctl(fd, DRM_IOCTL_MODE_DESTROY_DUMB, &dreq); > return ret; > } > > /* > * Finally! We have a connector with a suitable CRTC. We know which mode we want > * to use and we have a framebuffer of the correct size that we can write to. > * There is nothing special left to do. We only have to program the CRTC to > * connect each new framebuffer to each selected connector for each combination > * that we saved in the global modeset_list. > * This is done with a call to drmModeSetCrtc(). > * > * So we are ready for our main() function. First we check whether the user > * specified a DRM device on the command line, otherwise we use the default > * /dev/dri/card0. Then we open the device via modeset_open(). modeset_prepare() > * prepares all connectors and we can loop over "modeset_list" and call > * drmModeSetCrtc() on every CRTC/connector combination. > * > * But printing empty black pages is boring so we have another helper function > * modeset_draw() that draws some colors into the framebuffer for 5 seconds and > * then returns. And then we have all the cleanup functions which correctly free > * all devices again after we used them. All these functions are described below > * the main() function. > * > * As a side note: drmModeSetCrtc() actually takes a list of connectors that we > * want to control with this CRTC. We pass only one connector, though. As > * explained earlier, if we used multiple connectors, then all connectors would > * have the same controlling framebuffer so the output would be cloned. This is > * most often not what you want so we avoid explaining this feature here. > * Furthermore, all connectors will have to run with the same mode, which is > * also often not guaranteed. So instead, we only use one connector per CRTC. > * > * Before calling drmModeSetCrtc() we also save the current CRTC configuration. > * This is used in modeset_cleanup() to restore the CRTC to the same mode as was > * before we changed it. > * If we don't do this, the screen will stay blank after we exit until another > * application performs modesetting itself. > */ > > int main(int argc, char **argv) > { > int ret, fd; > const char *card; > struct modeset_dev *iter; > > /* check which DRM device to open */ > if (argc > 1) > card = argv[1]; > else > card = "/dev/dri/card0"; > > fprintf(stderr, "using card '%s'\n", card); > > /* open the DRM device */ > ret = modeset_open(&fd, card); > if (ret) > goto out_return; > > /* prepare all connectors and CRTCs */ > ret = modeset_prepare(fd); > if (ret) > goto out_close; > > /* perform actual modesetting on each found connector+CRTC */ > for (iter = modeset_list; iter; iter = iter->next) { > iter->saved_crtc = drmModeGetCrtc(fd, iter->crtc); > ret = drmModeSetCrtc(fd, iter->crtc, iter->fb, 0, 0, > &iter->conn, 1, &iter->mode); > if (ret) > fprintf(stderr, "cannot set CRTC for connector %u (%d): %m\n", > iter->conn, errno); > } > > /* draw some colors for 5seconds */ > modeset_draw(fd); > > /* cleanup everything */ > modeset_cleanup(fd); > > ret = 0; > > out_close: > close(fd); > out_return: > if (ret) { > errno = -ret; > fprintf(stderr, "modeset failed with error %d: %m\n", errno); > } else { > fprintf(stderr, "exiting\n"); > } > return ret; > } > > /* > * A short helper function to compute a changing color value. No need to > * understand it. > */ > > static uint8_t next_color(bool *up, uint8_t cur, unsigned int mod) > { > uint8_t next; > > next = cur + (*up ? 1 : -1) * (rand() % mod); > if ((*up && next < cur) || (!*up && next > cur)) { > *up = !*up; > next = cur; > } > > return next; > } > > static void crtc_lut(int fd, struct modeset_dev *dev, int p) > { > struct drm_mode_crtc_lut clut; > uint16_t r[256]; > uint16_t g[256]; > uint16_t b[256]; > int ret; > int i; > > /* prepare buffer for memory mapping */ > memset(&clut, 0, sizeof(clut)); > clut.crtc_id = dev->crtc; > clut.gamma_size = 256; > clut.red = (uint64_t)r; > clut.green = (uint64_t)g; > clut.blue = (uint64_t)b; > > for (i = 0; i < 256; ++i) { > r[i] = ((p + 2 * i) & 255) * 257; > g[i] = ((p + 3 * i) & 255) * 257; > b[i] = ((p + 5 * i) & 255) * 257; > } > ret = drmIoctl(fd, DRM_IOCTL_MODE_SETGAMMA, &clut); > if (ret) > fprintf(stderr, "cannot set gamma lut (%d): %m\n", > errno); > } > > /* > * modeset_draw(): This draws a solid color into all configured framebuffers. > * Every 100ms the color changes to a slightly different color so we get some > * kind of smoothly changing color-gradient. > * > * The color calculation can be ignored as it is pretty boring. So the > * interesting stuff is iterating over "modeset_list" and then through all lines > * and width. We then set each pixel individually to the current color. > * > * We do this 50 times as we sleep 100ms after each redraw round. This makes > * 50*100ms = 5000ms = 5s so it takes about 5seconds to finish this loop. > * > * Please note that we draw directly into the framebuffer. This means that you > * will see flickering as the monitor might refresh while we redraw the screen. > * To avoid this you would need to use two framebuffers and a call to > * drmModeSetCrtc() to switch between both buffers. > * You can also use drmModePageFlip() to do a vsync'ed pageflip. But this is > * beyond the scope of this document. > */ > > static void modeset_draw(int fd) > { > uint8_t p = 0; > unsigned int i, j, k; > struct modeset_dev *iter; > > for (iter = modeset_list; iter; iter = iter->next) { > for (k = 0; k < iter->width; ++k) { > for (j = 0; j < iter->height / 3; ++j) { > iter->map[iter->stride * j + k] = > k * 256 / iter->width; > } > for (; j < iter->height; ++j) > iter->map[iter->stride * j + k] = 26; > } > } > > for (i = 0; i < 50; ++i, ++p) { > for (iter = modeset_list; iter; iter = iter->next) > crtc_lut(fd, iter, p); > > usleep(100000); > } > } > > /* > * modeset_cleanup(fd): This cleans up all the devices we created during > * modeset_prepare(). It resets the CRTCs to their saved states and deallocates > * all memory. > * It should be pretty obvious how all of this works. > */ > > static void modeset_cleanup(int fd) > { > struct modeset_dev *iter; > struct drm_mode_destroy_dumb dreq; > > while (modeset_list) { > /* remove from global list */ > iter = modeset_list; > modeset_list = iter->next; > > /* restore saved CRTC configuration */ > drmModeSetCrtc(fd, > iter->saved_crtc->crtc_id, > iter->saved_crtc->buffer_id, > iter->saved_crtc->x, > iter->saved_crtc->y, > &iter->conn, > 1, > &iter->saved_crtc->mode); > drmModeFreeCrtc(iter->saved_crtc); > > /* unmap buffer */ > munmap(iter->map, iter->size); > > /* delete framebuffer */ > drmModeRmFB(fd, iter->fb); > > /* delete dumb buffer */ > memset(&dreq, 0, sizeof(dreq)); > dreq.handle = iter->handle; > drmIoctl(fd, DRM_IOCTL_MODE_DESTROY_DUMB, &dreq); > > /* free allocated memory */ > free(iter); > } > } > > /* > * I hope this was a short but easy overview of the DRM modesetting API. The DRM > * API offers much more capabilities including: > * - double-buffering or tripple-buffering (or whatever you want) > * - vsync'ed page-flips > * - hardware-accelerated rendering (for example via OpenGL) > * - output cloning > * - graphics-clients plus authentication > * - DRM planes/overlays/sprites > * - ... > * If you are interested in these topics, I can currently only redirect you to > * existing implementations, including: > * - plymouth (which uses dumb-buffers like this example; very easy to understand) > * - kmscon (which uses libuterm to do this) > * - wayland (very sophisticated DRM renderer; hard to understand fully as it > * uses more complicated techniques like DRM planes) > * - xserver (very hard to understand as it is split across many files/projects) > * > * But understanding how modesetting (as described in this document) works, is > * essential to understand all further DRM topics. > * > * Any feedback is welcome. Feel free to use this code freely for your own > * documentation or projects. > * > * - Hosted on http://github.com/dvdhrm/docs > * - Written by David Herrmann <dh.herrmann@xxxxxxxxxxxxxx> > */ > ----------------8<--------------- > > Peter Rosin (3): > drm: atmel-hlcdc: add support for 8-bit color lookup table mode > drm/fb-cma-helper: expose more of fb cma guts > drm: atmel-hlcdc: add clut support for legacy fbdev > > drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c | 58 +++++++++++++++++++++++++ > drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c | 25 ++++++++++- > drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h | 20 +++++++++ > drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c | 29 +++++++++++++ > drivers/gpu/drm/drm_fb_cma_helper.c | 55 ++++++++++++++++++----- > include/drm/drm_fb_cma_helper.h | 8 +++- > 6 files changed, 182 insertions(+), 13 deletions(-) > _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
