Hi,
On 11-11-2019 15:11, Ville Syrjälä wrote:
On Mon, Nov 11, 2019 at 10:50:42AM +0100, Hans de Goede wrote:
Hi,
On 11-11-2019 10:25, Daniel Vetter wrote:
On Sun, Nov 10, 2019 at 7:41 PM Hans de Goede hdegoede@redhat.com wrote:
drm_helper_probe_add_cmdline_mode() prefers using a probed mode matching a video= argument over calculating our own timings for the user specified mode using CVT or GTF.
But userspace code which is auto-configuring the mode may want to know that the user has specified that mode on the kernel commandline so that it can pick that mode over the mode which is marked as DRM_MODE_TYPE_PREFERRED.
This commit sets the DRM_MODE_TYPE_USERDEF flag on the matching mode, just as we would do on the user-specified mode when no matching probed mode is found.
Signed-off-by: Hans de Goede hdegoede@redhat.com
Will existing userspace dtrt here with this? Some links to popular ones would be good (since essentially this is uapi fine tuning we need that anyway). With that will get my ack.
A valid question, I've gone over what I consider the major userspace kms users: -Xorg xserver modesetting driver does not check for this: [hans@shalem xserver]$ ack DRM_MODE_TYPE_ hw/xfree86/drivers/modesetting/ hw/xfree86/drivers/modesetting/drmmode_display.c 1321: if (kmode->type & DRM_MODE_TYPE_DRIVER) 1323: if (kmode->type & DRM_MODE_TYPE_PREFERRED) -Other Xorg drivers: [hans@shalem driver]$ ls -d xf86-video-* xf86-video-amdgpu xf86-video-intel xf86-video-qxl xf86-video-armsoc xf86-video-modesetting xf86-video-sisusb xf86-video-ati xf86-video-nouveau xf86-video-vmware xf86-video-dummy xf86-video-omap xf86-video-voodoo xf86-video-geode xf86-video-opentegra These all only do the same checks as the Xorg modesetting driver -mutter: [hans@shalem mutter]$ ack DRM_MODE_TYPE_ src/backends/native/meta-output-kms.c 261: if (drm_mode->type & DRM_MODE_TYPE_PREFERRED)
So it seems nothing (that I can quickly find) in userspace is using this atm.
The reason I wrote this patch is because about a year ago plymouth used to fully rely on the kernel to setup the modes on monitors and would simply inherit the modes setup by the kernel. Basically plymouth was relying on fbcon to load first and setup modes.
Deferred fbcon takeover (for flickerfree) means that this is no longer happening. So now plymouth picks a mode itself. When I submitted the plymouth change for plymouth to pick a mode itself the plymouth maintainer (Ray Strode) was afraid that would break plymouth honoring video= arguments. So currently plymouth still relies on the kernel to do the mode setup if a video= argument is present on the kernel commandline.
Why can't plymouth just keep using the current mode if the crtc is already active and otherwise pick a mode itself?
Well for one the firmware may have setup an output with a non native mode because it always uses e.g 1024x768, we really want to switch to the preferred mode in that case.
We could only pick the current mode if the crtc is already active when video= is present on the kernel cmdline in an attempt to honor video= arguments, but that will only work if fbcon has already setup the modes according to the video= arguments and with flickerfree boot we defer loading fbcon until there are kernel are initrd errors to show. So in order to honor video= in a flickerfree setup plymouth needs to pick the requested mode itself. Actually knowing which mode is requested makes this a lot easier.
Regards,
Hans