[Intel-gfx] [PATCH v11 06/11] drm: Add DRM client cap for aspect-ratio

[Ville Syrjälä]

On Mon, Apr 23, 2018 at 10:43:47AM +0530, Nautiyal, Ankit K wrote:
> 
> 
> On 4/20/2018 7:37 PM, Ville Syrjälä wrote:
> > On Fri, Apr 20, 2018 at 07:01:46PM +0530, Nautiyal, Ankit K wrote:
> >> From: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
> >>
> >> To enable aspect-ratio support in DRM, blindly exposing the aspect
> >> ratio information along with mode, can break things in existing
> >> user-spaces which have no intention or support to use this aspect
> >> ratio information.
> >>
> >> To avoid this, a new drm client cap is required to enable a
> >> user-space to advertise if it supports modes with aspect-ratio. Based
> >> on this cap value, the kernel will take a call on exposing the aspect
> >> ratio info in modes or not.
> >>
> >> This patch adds the client cap for aspect-ratio.
> >>
> >> Cc: Ville Syrjala <ville.syrjala at linux.intel.com>
> >> Cc: Shashank Sharma <shashank.sharma at intel.com>
> >> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
> >>
> >> V3: rebase
> >> V4: As suggested by Marteen Lankhorst modified the commit message
> >>      explaining the need to use the DRM cap for aspect-ratio. Also,
> >>      tweaked the comment lines in the code for better understanding and
> >>      clarity, as recommended by Shashank Sharma.
> >> V5: rebase
> >> V6: rebase
> >> V7: rebase
> >> V8: rebase
> >> V9: rebase
> >> V10: added comment explaining that no userspace breaks on aspect-ratio
> >>       mode bits.
> >>
> >> Reviewed-by: Shashank Sharma <shashank.sharma at intel.com>
> >> ---
> >>   drivers/gpu/drm/drm_ioctl.c | 9 +++++++++
> >>   include/drm/drm_file.h      | 8 ++++++++
> >>   include/uapi/drm/drm.h      | 7 +++++++
> >>   3 files changed, 24 insertions(+)
> >>
> >> diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
> >> index af78291..39c8eab 100644
> >> --- a/drivers/gpu/drm/drm_ioctl.c
> >> +++ b/drivers/gpu/drm/drm_ioctl.c
> >> @@ -325,6 +325,15 @@ drm_setclientcap(struct drm_device *dev, void *data, struct drm_file *file_priv)
> >>   		file_priv->atomic = req->value;
> >>   		file_priv->universal_planes = req->value;
> >>   		break;
> >> +	case DRM_CLIENT_CAP_ASPECT_RATIO:
> >> +		if (req->value > 1)
> >> +			return -EINVAL;
> >> +	/*
> >> +	 * No Atomic userspace blows up on aspect ratio mode bits. Checked in
> >> +	 * wayland/weston, xserver, and hardware-composer modeset paths.
> >> +	 */
> > Bogus indentation.
> 
> Thanks to point that out, will fix this.
> 
> > Also where's the aspect_ratio_allowed handling for the atomic cap?
> > Or did we decide against it after all?
> 
> As discussed, aspect ratio is handled in the atomic modeset path, where 
> in the modeset requests with aspect-ratios
> are rejected, if the aspect-ratio cap not set.

That is not what we discussed on irc. What Daniel was suggesting is
always enabling the aspect ratio cap for atomic clients, just as we
already enable the univerals planes cap for atomic clients.

-- 
Ville Syrjälä
Intel