Hi Emil,
Maybe here is your missing comments
I ’m really sorry, sometimes I forget to use plain text by gmail,
never make the same mistake again.
Emil Velikov <emil.l.velikov@xxxxxxxxx> 于2020年3月3日周二 上午2:29写道：
>
> Hi Kevin,
>
> There's a few small suggestions, although overall the driver looks a lot better.
>
> On Thu, 27 Feb 2020 at 08:14, Kevin Tang <kevin3.tang@xxxxxxxxx> wrote:
>
> > --- /dev/null
> > +++ b/drivers/gpu/drm/sprd/dpu/Makefile
> > @@ -0,0 +1,7 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +
> > +ifdef CONFIG_ARM64
> > +KBUILD_CFLAGS += -mstrict-align
>
>
> There are many other drivers that do not use readl/writel for register access,
> yet none has this workaround... Even those that they are exclusively ARM64.
>
> Have you tried that it's not a buggy version of GCC? At the very least, I'd
> encourage you to add a brief comment about the problem + setup.
>
> ... In general I think one should follow the suggestions from Rob Herring.
>
Yocto v2.5
aarch64-linaro-linux-gcc (Linaro GCC 7.2-2017.11) 7.2.1 20171011
Crash Stack:
/sprd/drv/dispc/dpu_r2p0.c:729
1796256 ffffff8008486650: f803c043 stur x3, [x2,#60]
=>Unhandled fault: alignment fault (0x96000061) at 0xffffff80098b883c
729 reg->mmu_min_ppn1 = 0;
730 reg->mmu_ppn_range1 = 0xffff;
731 reg->mmu_min_ppn2 = 0;
732 reg->mmu_ppn_range2 = 0xffff;
The above C code operation are continuous. The compiler may think that
the access can be completed by directly using two 64-bit assignment
operations, so it is optimized to 64-bit operation.
Assembly code：
=============================
/sprd/drv/dispc/dpu_r2p0.c:729
1796244 ffffff8008486638: 91200022 add x2, x1, #0x800
/sprd/drv/dispc/dpu_r2p0.c:728
1796246 ffffff800848663c: b908003f str wzr, [x1,#2048]
/sprd/drv/dispc/dpu_r2p0.c:729
1796248 ffffff8008486640: d2dfffe3 mov x3,
#0xffff00000000
/sprd/drv/dispc/dpu_r2p0.c:733
1796250 ffffff8008486644: 12bfffc4 mov w4, #0x1ffff
/sprd/drv/dispc/dpu_r2p0.c:735
1796252 ffffff8008486648: 529fffe5 mov w5, #0xffff
/sprd/drv/dispc/dpu_r2p0.c:741
1796254 ffffff800848664c: 52800000 mov w0, #0x0
/sprd/drv/dispc/dpu_r2p0.c:729
1796256 ffffff8008486650: f803c043 stur x3, [x2,#60]
=>Unhandled fault: alignment fault (0x96000061) at 0xffffff80098b883c
/sprd/drv/dispc/dpu_r2p0.c:730
1796258 ffffff8008486654: f8044043 stur x3, [x2,#68]
/sprd/drv/dispc/dpu_r2p0.c:735
1796260 ffffff8008486658: b901e425 str w5, [x1,#484]
/sprd/drv/dispc/dpu_r2p0.c:733
1796262 ffffff800848665c: b9080c24 str w4, [x1,#2060]
1796263 ffffff8008486660: f9400274 ldr x20, [x19]
>
>
> > +static void dpu_dump(struct dpu_context *ctx)
> > +{
> > + u32 *reg = (u32 *)ctx->base;
> > + int i;
> > +
> > + pr_info(" 0 4 8 C\n");
> > + for (i = 0; i < 256; i += 4) {
> > + pr_info("%04x: 0x%08x 0x%08x 0x%08x 0x%08x\n",
> > + i * 4, reg[i], reg[i + 1], reg[i + 2], reg[i + 3]);
>
> Using some of the helpers from drm_print.h would be better than pr_*.
> This applies for the rest of the patch.
>
>
> > +static void dpu_clean_all(struct dpu_context *ctx)
> > +{
> > + int i;
> > + struct dpu_reg *reg = (struct dpu_reg *)ctx->base;
> > +
> > + for (i = 0; i < 8; i++)
>
> This "< 8" seem pretty magical. How about "< ARRAY_SIZE(reg->layers)"
> Same logic applies through the rest of the patch.
>
>
> > +static int dpu_wait_stop_done(struct dpu_context *ctx)
> > +{
> > + int rc;
> > +
> > + if (ctx->stopped)
> > + return 0;
> > +
> The stopped handling does look suspicious. Admittedly I did not look too closely
> at the dpu_flip code, which seems to require it.
>
> Let's add a small comment in the struct dpu_context::stopped declaration, why it
> is needed, if it truely is.
>
> > + rc = wait_event_interruptible_timeout(ctx->wait_queue, ctx->evt_stop,
> > + msecs_to_jiffies(500));
> > + ctx->evt_stop = false;
> > +
> > + ctx->stopped = true;
> > +
> > + if (!rc) {
> > + pr_err("dpu wait for stop done time out!\n");
> > + return -ETIMEDOUT;
> > + }
> > +
> > + return 0;
> > +}
> > +
>
> > +static void dpu_stop(struct dpu_context *ctx)
> > +{
> > + struct dpu_reg *reg = (struct dpu_reg *)ctx->base;
> > +
> > + if (ctx->stopped)
> > + return;
> > +
> > + if (ctx->if_type == SPRD_DISPC_IF_DPI)
> > + reg->dpu_ctrl |= BIT(1);
> > +
> > + dpu_wait_stop_done(ctx);
> > +
> > + pr_info("dpu stop\n");
>
> This and the dpu_run pr_info() messages can be removed.
>
>
> > +}
> > +
> > +static void dpu_run(struct dpu_context *ctx)
> > +{
> > + struct dpu_reg *reg = (struct dpu_reg *)ctx->base;
> > +
> > + if (!ctx->stopped)
> > + return;
> > +
> > + reg->dpu_ctrl |= BIT(0);
> > +
> > + ctx->stopped = false;
> > +
> > + pr_info("dpu run\n");
> > +}
> > +
> > +static int dpu_init(struct dpu_context *ctx)
> > +{
> > + struct dpu_reg *reg = (struct dpu_reg *)ctx->base;
> > + u32 size;
> > +
> > + reg->bg_color = 0;
> > +
> > + size = (ctx->vm.vactive << 16) | ctx->vm.hactive;
> > + reg->panel_size = size;
> > + reg->blend_size = size;
> > +
> > + reg->dpu_cfg0 = BIT(4) | BIT(5);
> > +
> > + reg->dpu_cfg1 = 0x004466da;
> > + reg->dpu_cfg2 = 0;
> > +
> > + if (ctx->stopped)
> > + dpu_clean_all(ctx);
> > +
> > + reg->mmu_en = 0;
> > + reg->mmu_min_ppn1 = 0;
> > + reg->mmu_ppn_range1 = 0xffff;
> > + reg->mmu_min_ppn2 = 0;
> > + reg->mmu_ppn_range2 = 0xffff;
> > + reg->mmu_vpn_range = 0x1ffff;
> > +
> > + reg->dpu_int_clr = 0xffff;
> > +
> > + init_waitqueue_head(&ctx->wait_queue);
> > +
> > + return 0;
>
> Function always returns 0. Let's make it static void dpu_init()
>
>
>
> > +static u32 to_dpu_rotation(u32 angle)
> > +{
> > + u32 rot = DPU_LAYER_ROTATION_0;
> > +
> > + switch (angle) {
> > + case 0:
> > + case DRM_MODE_ROTATE_0:
> > + rot = DPU_LAYER_ROTATION_0;
> > + break;
> > + case DRM_MODE_ROTATE_90:
> > + rot = DPU_LAYER_ROTATION_90;
> > + break;
> > + case DRM_MODE_ROTATE_180:
> > + rot = DPU_LAYER_ROTATION_180;
> > + break;
> > + case DRM_MODE_ROTATE_270:
> > + rot = DPU_LAYER_ROTATION_270;
> > + break;
> > + case DRM_MODE_REFLECT_Y:
> > + rot = DPU_LAYER_ROTATION_180_M;
> > + break;
> > + case (DRM_MODE_REFLECT_Y | DRM_MODE_ROTATE_90):
> > + rot = DPU_LAYER_ROTATION_90_M;
> > + break;
> > + case DRM_MODE_REFLECT_X:
> > + rot = DPU_LAYER_ROTATION_0_M;
> > + break;
> > + case (DRM_MODE_REFLECT_X | DRM_MODE_ROTATE_90):
> > + rot = DPU_LAYER_ROTATION_270_M;
> > + break;
> > + default:
> > + pr_err("rotation convert unsupport angle (drm)= 0x%x\n", angle);
> > + break;
>
> Have you seen a case where the 0 or default case are reached? AFAICT they will
> never trigger. So one might as well use:
> switch (angle) {
> case DRM_MODE_FOO:
> return DPU_LAYER_ROTATION_FOO;
> ...
> case DRM_MODE_BAR:
> return DPU_LAYER_ROTATION_BAR;
> }
>
>
> > + }
> > +
> > + return rot;
> > +}
> > +
> > +static u32 dpu_img_ctrl(u32 format, u32 blending, u32 rotation)
> > +{
> > + int reg_val = 0;
> > +
> > + /* layer enable */
> > + reg_val |= BIT(0);
> > +
> > + switch (format) {
> > + case DRM_FORMAT_BGRA8888:
> > + /* BGRA8888 -> ARGB8888 */
> > + reg_val |= SPRD_IMG_DATA_ENDIAN_B3B2B1B0 << 8;
> > + reg_val |= (DPU_LAYER_FORMAT_ARGB8888 << 4);
> > + break;
> > + case DRM_FORMAT_RGBX8888:
> > + case DRM_FORMAT_RGBA8888:
> > + /* RGBA8888 -> ABGR8888 */
> > + reg_val |= SPRD_IMG_DATA_ENDIAN_B3B2B1B0 << 8;
> > + /* FALLTHRU */
> > + case DRM_FORMAT_ABGR8888:
> > + /* rb switch */
> > + reg_val |= BIT(10);
> > + /* FALLTHRU */
> > + case DRM_FORMAT_ARGB8888:
> > + reg_val |= (DPU_LAYER_FORMAT_ARGB8888 << 4);
> > + break;
> > + case DRM_FORMAT_XBGR8888:
> > + /* rb switch */
> > + reg_val |= BIT(10);
> > + /* FALLTHRU */
> > + case DRM_FORMAT_XRGB8888:
> > + reg_val |= (DPU_LAYER_FORMAT_ARGB8888 << 4);
> > + break;
> > + case DRM_FORMAT_BGR565:
> > + /* rb switch */
> > + reg_val |= BIT(10);
> > + /* FALLTHRU */
> > + case DRM_FORMAT_RGB565:
> > + reg_val |= (DPU_LAYER_FORMAT_RGB565 << 4);
> > + break;
> > + case DRM_FORMAT_NV12:
> > + /* 2-Lane: Yuv420 */
> > + reg_val |= DPU_LAYER_FORMAT_YUV420_2PLANE << 4;
> > + /* Y endian */
> > + reg_val |= SPRD_IMG_DATA_ENDIAN_B0B1B2B3 << 8;
> > + /* UV endian */
> > + reg_val |= SPRD_IMG_DATA_ENDIAN_B0B1B2B3 << 10;
> > + break;
> > + case DRM_FORMAT_NV21:
> > + /* 2-Lane: Yuv420 */
> > + reg_val |= DPU_LAYER_FORMAT_YUV420_2PLANE << 4;
> > + /* Y endian */
> > + reg_val |= SPRD_IMG_DATA_ENDIAN_B0B1B2B3 << 8;
> > + /* UV endian */
> > + reg_val |= SPRD_IMG_DATA_ENDIAN_B3B2B1B0 << 10;
> > + break;
> > + case DRM_FORMAT_NV16:
> > + /* 2-Lane: Yuv422 */
> > + reg_val |= DPU_LAYER_FORMAT_YUV422_2PLANE << 4;
> > + /* Y endian */
> > + reg_val |= SPRD_IMG_DATA_ENDIAN_B3B2B1B0 << 8;
> > + /* UV endian */
> > + reg_val |= SPRD_IMG_DATA_ENDIAN_B3B2B1B0 << 10;
> > + break;
> > + case DRM_FORMAT_NV61:
> > + /* 2-Lane: Yuv422 */
> > + reg_val |= DPU_LAYER_FORMAT_YUV422_2PLANE << 4;
> > + /* Y endian */
> > + reg_val |= SPRD_IMG_DATA_ENDIAN_B0B1B2B3 << 8;
> > + /* UV endian */
> > + reg_val |= SPRD_IMG_DATA_ENDIAN_B0B1B2B3 << 10;
> > + break;
> > + case DRM_FORMAT_YUV420:
> > + reg_val |= DPU_LAYER_FORMAT_YUV420_3PLANE << 4;
> > + /* Y endian */
> > + reg_val |= SPRD_IMG_DATA_ENDIAN_B0B1B2B3 << 8;
> > + /* UV endian */
> > + reg_val |= SPRD_IMG_DATA_ENDIAN_B0B1B2B3 << 10;
> > + break;
> > + case DRM_FORMAT_YVU420:
> > + reg_val |= DPU_LAYER_FORMAT_YUV420_3PLANE << 4;
> > + /* Y endian */
> > + reg_val |= SPRD_IMG_DATA_ENDIAN_B0B1B2B3 << 8;
> > + /* UV endian */
> > + reg_val |= SPRD_IMG_DATA_ENDIAN_B3B2B1B0 << 10;
> > + break;
> > + default:
> > + pr_err("error: invalid format %c%c%c%c\n", format,
> > + format >> 8,
> > + format >> 16,
> > + format >> 24);
> > + break;
> The default case here should be unreachable. Either it is or the upper layer (or
> earlier code) should ensure that.
>
> > + }
> > +
> > + switch (blending) {
> > + case DRM_MODE_BLEND_PIXEL_NONE:
> > + /* don't do blending, maybe RGBX */
> > + /* alpha mode select - layer alpha */
> > + reg_val |= BIT(2);
> > + break;
> > + case DRM_MODE_BLEND_COVERAGE:
> > + /* alpha mode select - combo alpha */
> > + reg_val |= BIT(3);
> > + /*Normal mode*/
> > + reg_val &= (~BIT(16));
> > + break;
> > + case DRM_MODE_BLEND_PREMULTI:
> > + /* alpha mode select - combo alpha */
> > + reg_val |= BIT(3);
> > + /*Pre-mult mode*/
> > + reg_val |= BIT(16);
> > + break;
> > + default:
> > + /* alpha mode select - layer alpha */
> > + reg_val |= BIT(2);
> > + break;
> Ditto
>
> > + }
> > +
> > + rotation = to_dpu_rotation(rotation);
> > + reg_val |= (rotation & 0x7) << 20;
> > +
> > + return reg_val;
> > +}
> > +
>
> > +static void dpu_layer(struct dpu_context *ctx,
> > + struct sprd_dpu_layer *hwlayer)
> > +{
> > + struct dpu_reg *reg = (struct dpu_reg *)ctx->base;
> > + const struct drm_format_info *info;
> > + struct layer_reg *layer;
> > + u32 addr, size, offset;
> > + int i;
> > +
> > + layer = ®->layers[hwlayer->index];
> > + offset = (hwlayer->dst_x & 0xffff) | ((hwlayer->dst_y) << 16);
> > +
> > + if (hwlayer->src_w && hwlayer->src_h)
> > + size = (hwlayer->src_w & 0xffff) | ((hwlayer->src_h) << 16);
> > + else
> > + size = (hwlayer->dst_w & 0xffff) | ((hwlayer->dst_h) << 16);
> > +
> > + for (i = 0; i < hwlayer->planes; i++) {
> > + addr = hwlayer->addr[i];
> > +
> > + if (addr % 16)
> > + pr_err("layer addr[%d] is not 16 bytes align, it's 0x%08x\n",
> > + i, addr);
> > + layer->addr[i] = addr;
> > + }
> > +
> > + layer->pos = offset;
> > + layer->size = size;
> > + layer->crop_start = (hwlayer->src_y << 16) | hwlayer->src_x;
> > + layer->alpha = hwlayer->alpha;
> > +
> > + info = drm_format_info(hwlayer->format);
> > + if (info->cpp[0] == 0) {
>
> Ditto
>
> > + pr_err("layer[%d] bytes per pixel is invalid\n", hwlayer->index);
> > + return;
> > + }
> > +
>
>
>
>
> > +static int dpu_capability(struct dpu_context *ctx,
> > + struct dpu_capability *cap)
> > +{
> > + if (!cap)
> > + return -EINVAL;
> > +
> Ensure the caller always passes cap != NULL and drop the function return type?
>
> > + cap->max_layers = 6;
> > + cap->fmts_ptr = primary_fmts;
> > + cap->fmts_cnt = ARRAY_SIZE(primary_fmts);
> > +
> > + return 0;
> > +}
>
>
> > +static int sprd_plane_atomic_check(struct drm_plane *plane,
> > + struct drm_plane_state *state)
> > +{
> > + DRM_DEBUG("%s()\n", __func__);
> > +
>
> Would be nice to hear from the atomic experts, how a no-op atomic_check goes
> with the overall atomic semantics.
>
>
> > + return 0;
> > +}
> > +
>
>
> > +static void sprd_plane_atomic_disable(struct drm_plane *plane,
> > + struct drm_plane_state *old_state)
> > +{
> > + struct sprd_plane *p = to_sprd_plane(plane);
> > +
> > + /*
> > + * NOTE:
> > + * The dpu->core->flip() will disable all the planes each time.
> > + * So there is no need to impliment the atomic_disable() function.
> > + * But this function can not be removed, because it will change
> > + * to call atomic_update() callback instead. Which will cause
> > + * kernel panic in sprd_plane_atomic_update().
> > + *
> > + * We do nothing here but just print a debug log.
> > + */
> > + DRM_DEBUG("%s() layer_id = %u\n", __func__, p->index);
>
> Similar to the check - would be nice to see a confirmation, that this isn't
> abusing atomics in some way.
>
>
> > +}
> > +
> > +static int sprd_plane_create_properties(struct sprd_plane *p, int index)
> > +{
> > + unsigned int supported_modes = BIT(DRM_MODE_BLEND_PIXEL_NONE) |
> > + BIT(DRM_MODE_BLEND_PREMULTI) |
> > + BIT(DRM_MODE_BLEND_COVERAGE);
> > +
> > + /* create rotation property */
> > + drm_plane_create_rotation_property(&p->plane,
> > + DRM_MODE_ROTATE_0,
> > + DRM_MODE_ROTATE_MASK |
> > + DRM_MODE_REFLECT_MASK);
> > +
> > + /* create alpha property */
> > + drm_plane_create_alpha_property(&p->plane);
> > +
> > + /* create blend mode property */
> > + drm_plane_create_blend_mode_property(&p->plane, supported_modes);
> > +
> > + /* create zpos property */
> > + drm_plane_create_zpos_immutable_property(&p->plane, index);
> > +
> Either check if creating the properties fail (and propagate the error) or drop
> the function return type. As-is it's in the middle making it fairly misleading.
>
> > + return 0;
> > +}
> > +
>
>
> > +static struct drm_plane *sprd_plane_init(struct drm_device *drm,
> > + struct sprd_dpu *dpu)
> > +{
> > + struct drm_plane *primary = NULL;
> > + struct sprd_plane *p = NULL;
> > + struct dpu_capability cap = {};
> > + int err, i;
> > +
> > + if (dpu->core && dpu->core->capability)
> As mentioned before - this always evaluates to true, so drop the check.
> Same applies for the other dpu->core->foo checks.
>
> Still not a huge fan of the abstraction layer, but I guess you're hesitant on
> removing it.
Here is the complete implementation of our "sprd_dpu_init":
if (dpu->glb && dpu->glb->power)
dpu->glb->power(ctx, true);
if (dpu->glb && dpu->glb->enable)
dpu->glb->enable(ctx);
if (ctx->is_stopped && dpu->glb && dpu->glb->reset)
dpu->glb->reset(ctx);
if (dpu->clk && dpu->clk->init)
dpu->clk->init(ctx);
if (dpu->clk && dpu->clk->enable)
dpu->clk->enable(ctx);
if (dpu->core && dpu->core->init)
dpu->core->init(ctx);
if (dpu->core && dpu->core->ifconfig)
dpu->core->ifconfig(ctx);
“dpu->core", "dpu->clk", "dpu->glb" checking maybe is not needed, i
will remove it.
But, Eg: "dpu->glb->power" not always need for all h/w
So in order to keep the same coding style, could i do like this:
if (dpu->glb->power)
dpu->glb->power(ctx, true);
if (dpu->glb->enable)
dpu->glb->enable(ctx);
......
But here, "dpu->core->capability", your are right, this always evaluates to true
So i will remove the error checking about always being true...
>
> > + dpu->core->capability(&dpu->ctx, &cap);
> > +
> > + dpu->layers = devm_kcalloc(drm->dev, cap.max_layers,
> > + sizeof(struct sprd_dpu_layer), GFP_KERNEL);
> > + if (!dpu->layers)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + for (i = 0; i < cap.max_layers; i++) {
> > +
> > + p = devm_kzalloc(drm->dev, sizeof(*p), GFP_KERNEL);
> > + if (!p)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + err = drm_universal_plane_init(drm, &p->plane, 1,
> > + &sprd_plane_funcs, cap.fmts_ptr,
> > + cap.fmts_cnt, NULL,
> > + DRM_PLANE_TYPE_PRIMARY, NULL);
> > + if (err) {
> > + DRM_ERROR("fail to init primary plane\n");
> > + return ERR_PTR(err);
> > + }
> > +
> > + drm_plane_helper_add(&p->plane, &sprd_plane_helper_funcs);
> > +
> > + sprd_plane_create_properties(p, i);
> > +
> > + p->index = i;
> > + if (i == 0)
> > + primary = &p->plane;
> > + }
> > +
> > + if (p)
> > + DRM_INFO("dpu plane init ok\n");
>
> This and nearly all the other DRM_INFO() messages look like a debug/development
> left over. Please remove them - the driver does not need to print when functions
> are successfull.
>
>
> > +
> > + return primary;
> > +}
> > +
> > +static void sprd_crtc_mode_set_nofb(struct drm_crtc *crtc)
> > +{
> > + struct sprd_dpu *dpu = crtc_to_dpu(crtc);
> > +
> > + if ((dpu->mode->hdisplay == dpu->mode->htotal) ||
> > + (dpu->mode->vdisplay == dpu->mode->vtotal))
> > + dpu->ctx.if_type = SPRD_DISPC_IF_EDPI;
> > + else
> > + dpu->ctx.if_type = SPRD_DISPC_IF_DPI;
> > +}
> > +
> > +static enum drm_mode_status sprd_crtc_mode_valid(struct drm_crtc *crtc,
> > + const struct drm_display_mode *mode)
> > +{
> > + struct sprd_dpu *dpu = crtc_to_dpu(crtc);
> > +
> > + DRM_INFO("%s() mode: "DRM_MODE_FMT"\n", __func__, DRM_MODE_ARG(mode));
> > +
>
> If needed, let's move this to core and make it a debug message. As-is it will
> cause spam for no reason.
>
>
> > + if (mode->type & DRM_MODE_TYPE_DEFAULT)
> > + dpu->mode = (struct drm_display_mode *)mode;
> > +
> > + if (mode->type & DRM_MODE_TYPE_PREFERRED) {
> > + dpu->mode = (struct drm_display_mode *)mode;
>
> Casting away the constness is a bad idea.
>
> Instead, let's move the if_type decision here, thus we can remove the
> nsprd_crtc_mode_set_nofb function? This way we can also remove sprd_dpu::mode.
>
>
> > + drm_display_mode_to_videomode(dpu->mode, &dpu->ctx.vm);
>
> Similarly, one could derive the vm based attributes here and remove dpu->ctx.vm.
>
>
> > + }
> > +
> > + return MODE_OK;
> > +}
> > +
> > +static void sprd_crtc_atomic_enable(struct drm_crtc *crtc,
> > + struct drm_crtc_state *old_state)
> > +{
> > + struct sprd_dpu *dpu = crtc_to_dpu(crtc);
> > +
> > + DRM_INFO("%s()\n", __func__);
> > +
> More sprurious info messages - debug leftover?
>
>
>
> > +static int sprd_crtc_enable_vblank(struct drm_crtc *crtc)
> > +{
> > + struct sprd_dpu *dpu = crtc_to_dpu(crtc);
> > +
> > + DRM_DEBUG("%s()\n", __func__);
> > +
> Personally, I don't see the appeal in these debug messages. While a few display
> controllers have the odd piece, they are an exception in DRM.
>
>
>
> > +static int sprd_crtc_create_properties(struct drm_crtc *crtc)
> > +{
> > + struct sprd_dpu *dpu = crtc_to_dpu(crtc);
> > + struct drm_device *drm = dpu->crtc.dev;
> > + struct drm_property *prop;
> > + struct drm_property_blob *blob;
> > + size_t blob_size;
> > +
> > + blob_size = strlen(dpu->ctx.version) + 1;
> > +
> > + blob = drm_property_create_blob(dpu->crtc.dev, blob_size,
> > + dpu->ctx.version);
> > + if (IS_ERR(blob)) {
> > + DRM_ERROR("drm_property_create_blob dpu version failed\n");
> > + return PTR_ERR(blob);
> > + }
> > +
> > + /* create dpu version property */
> > + prop = drm_property_create(drm,
> > + DRM_MODE_PROP_IMMUTABLE | DRM_MODE_PROP_BLOB,
> > + "dpu version", 0);
>
> Note: Custom properties should be separate patches. This includes documentation
> why they are needed and references to open-source userspace.
>
>
> HTH
> Emil
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