Den 09.06.2017 22.59, skrev Marco Diego Aurélio Mesquita:
Hi Devs!
On Thu, Jun 8, 2017 at 4:08 AM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
I don't think that using cma for the gm12u320 is a good idea, it will
typically be used as a secondary GPU output together with a real GPU
extending the desktop by being a prime display output. So for the memory
management stuff I would keep the code copied from the udl driver (which
we may later split out in a separate helper lib for devices where
the framebuffer is in normal system memory and we have some scather-gather
capable process copying it to the real device over e.g. USB)
I got the PL111 driver and stripped all device specific code. Also, I
added the get_modes and driver usb probe functions from gm12u320. The
resulting code is available in
https://gitlab.com/marcodiego/dummy-display-driver .
The driver compiles, loads, identifies the device when I plug it,
/dev/fb1 is created adequately but it stops there. Gnome monitors tool
does not see it as a new monitor. What I expected was that it would be
seen as a new monitor and that I could even activate it. Instead,
syslog complains: "Cannot find any crtc or sizes".
Anyway, I think this is a first step. My first doubt: where should I
go from now? What should I change in the driver so that gnome monitors
tool sees it as a new monitor and I could activate it, even if it
works as a mere dummy device?
Second doubt is: is this really the simplest/best way? I mean, the
repaper driver that Emil pointed seems a lot simpler, wouldn't it be
better to mimic it? How complicated is it to modify the repaper driver
to build a dummy driver?
By dummy driver, I mean something that gnome monitors tools can
identify as a new monitor and I can activate it. I hope to reach a
point where the update or dirty callback is called. From that point on
it is just a matter of sending the framebuffer through USB the way
gm12u320 does currently.
I guess you have forgotten to replace connector detect, because I
didn't see you use drm_panel in your RFC.
(gm12u320_connector->panel is NULL afaict, so it's always disconnected)
static enum drm_connector_status gm12u320_connector_detect(struct
drm_connector
*connector, bool force)
{
- struct gm12u320_drm_connector *gm12u320_connector =
- to_gm12u320_connector(connector);
-
- return (gm12u320_connector->panel ?
- connector_status_connected :
- connector_status_disconnected);
+ if (drm_device_is_unplugged(connector->dev))
+ return connector_status_disconnected;
+
+ return connector_status_connected;
}
Something like this should give you the dirty callback:
static int gm12u320_fb_dirty(struct drm_framebuffer *fb,
struct drm_file *file_priv,
unsigned int flags, unsigned int color,
struct drm_clip_rect *clips,
unsigned int num_clips)
{
struct drm_gem_cma_object *cma_obj = drm_fb_cma_get_gem_obj(fb, 0);
void *src = cma_obj->vaddr;
printk("FBDIRTY\n");
}
static const struct drm_framebuffer_funcs gm12u320_fb_funcs = {
.destroy = drm_fb_cma_destroy,
.create_handle = drm_fb_cma_create_handle,
.dirty = gm12u320_fb_dirty,
};
static struct drm_framebuffer *
gm12u320_fb_create(struct drm_device *drm, struct drm_file *file_priv,
const struct drm_mode_fb_cmd2 *mode_cmd)
{
return drm_fb_cma_create_with_funcs(drm, file_priv, mode_cmd,
&gm12u320_fb_funcs);
}
static struct drm_mode_config_funcs mode_config_funcs = {
.fb_create = gm12u320_fb_create,
.atomic_check = drm_atomic_helper_check,
.atomic_commit = drm_atomic_helper_commit,
};
The repaper driver is based on tinydrm which uses the CMA library.
Hans said that cma wasn't appropriate for your monitor.
It will be difficult to go from a working tinydrm driver to one based
on the udl GEM functions.
I don't know gnome monitors tools, so I can't comment on that.
Noralf.
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