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

[Ville Syrjälä]

On Mon, Apr 23, 2018 at 01:11:25PM +0300, Ville Syrjälä wrote:
> 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.

And to make sure we're on the same page finally

@@ -320,14 +320,15 @@ drm_setclientcap(struct drm_device *dev, void *data, struct drm_file *file_priv)
        case DRM_CLIENT_CAP_ATOMIC:
                if (!drm_core_check_feature(dev, DRIVER_ATOMIC))
                        return -EINVAL;
                if (req->value > 1)
                        return -EINVAL;
                file_priv->atomic = req->value;
                file_priv->universal_planes = req->value;
+               file_priv->aspect_ratio_allowed = req->value;
                break;
        default:
                return -EINVAL;
        }
 
        return 0;
 }

is what we're talking about here.

-- 
Ville Syrjälä
Intel