On 10/17/2016 8:30 PM, Ville Syrjälä wrote:
On Mon, Oct 17, 2016 at 08:21:21PM +0530, Sharma, Shashank wrote:


On 10/17/2016 7:36 PM, Ville Syrjälä wrote:
On Mon, Oct 17, 2016 at 07:10:42PM +0530, Sharma, Shashank wrote:


On 10/17/2016 6:01 PM, Ville Syrjälä wrote:
On Mon, Oct 17, 2016 at 05:34:38PM +0530, Shashank Sharma wrote:
Current DRM layer functions don't parse aspect ratio information
while converting a user mode->kernel mode or vice versa. This
causes modeset to pick mode with wrong aspect ratio, eventually
causing failures in HDMI compliance test cases, due to wrong VIC.

This patch adds aspect ratio information in DRM's mode conversion
and mode comparision functions, to make sure kernel picks mode
with right aspect ratio (as per the VIC).

Signed-off-by: Shashank Sharma <>
Signed-off-by: Lin, Jia <>
Signed-off-by: Akashdeep Sharma <>
Reviewed-by: Jim Bride <>
Reviewed-by: Jose Abreu <>
Cc: Daniel Vetter <>
Cc: Emil Velikov <>

V2: Addressed review comments from Sean:
- Fix spellings/typo
- No need to handle aspect ratio none
- Add a break, for default case too
V3: Rebase
V4: Added r-b from Jose
    drivers/gpu/drm/drm_modes.c | 31 +++++++++++++++++++++++++++++++
    1 file changed, 31 insertions(+)

diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index 53f07ac..fde927a 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -997,6 +997,7 @@ bool drm_mode_equal_no_clocks_no_stereo(const struct 
drm_display_mode *mode1,
            mode1->vsync_end == mode2->vsync_end &&
            mode1->vtotal == mode2->vtotal &&
            mode1->vscan == mode2->vscan &&
+           mode1->picture_aspect_ratio == mode2->picture_aspect_ratio &&
            (mode1->flags & ~DRM_MODE_FLAG_3D_MASK) ==
             (mode2->flags & ~DRM_MODE_FLAG_3D_MASK))
                return true;
@@ -1499,6 +1500,21 @@ void drm_mode_convert_to_umode(struct drm_mode_modeinfo 
        out->vrefresh = in->vrefresh;
        out->flags = in->flags;
        out->type = in->type;
+       out->flags &= ~DRM_MODE_FLAG_PIC_AR_MASK;
+       switch (in->picture_aspect_ratio) {
+       case HDMI_PICTURE_ASPECT_4_3:
+               out->flags |= DRM_MODE_FLAG_PIC_AR_4_3;
+               break;
+       case HDMI_PICTURE_ASPECT_16_9:
+               out->flags |= DRM_MODE_FLAG_PIC_AR_16_9;
+               break;
+       default:
+               out->flags |= DRM_MODE_FLAG_PIC_AR_NONE;
+               break;
+       }
        strncpy(out->name, in->name, DRM_DISPLAY_MODE_LEN);
        out->name[DRM_DISPLAY_MODE_LEN-1] = 0;
@@ -1544,6 +1560,21 @@ int drm_mode_convert_umode(struct drm_display_mode *out,
        strncpy(out->name, in->name, DRM_DISPLAY_MODE_LEN);
        out->name[DRM_DISPLAY_MODE_LEN-1] = 0;
+ /* Clearing picture aspect ratio bits from out flags */
+       out->flags &= ~DRM_MODE_FLAG_PIC_AR_MASK;
+       switch (in->flags & DRM_MODE_FLAG_PIC_AR_MASK) {
+       case DRM_MODE_FLAG_PIC_AR_4_3:
+               out->picture_aspect_ratio |= HDMI_PICTURE_ASPECT_4_3;
+               break;
+       case DRM_MODE_FLAG_PIC_AR_16_9:
+               out->picture_aspect_ratio |= HDMI_PICTURE_ASPECT_16_9;
+               break;
+       default:
+               out->picture_aspect_ratio = HDMI_PICTURE_ASPECT_NONE;
+               break;
+       }
Hmm. So now we have the mode aspect ratio infromation duplicated
in two different places. Not sure that won't lead to some confusion.
In drm layer, this is the only place. Actually till now, DRM layer dint
have the support for aspect ratio at all. This was causing
HDMI compliance tests like 7-27 fail, which expect a particular unique
VIC in AVI infoframe on modeset.

I have given some details about this in cover-letter.
Although we do want the user to be able to override via the property I
suppose, so we'd have to change that (+ the inforframe code) to
look at the mode flags instead if we would eliminate
I had a small discussion on this with Daniel, and we discussed that it
doesnt make sense to override just the aspect ratio if the monitor
doesn't even support that aspect ratio.
And currently the was how this property is implemented is, we just
override the aspect ratio without any validity check.

Now as we have all the supported aspect ratio added properly in the mode
info itself, we need not to have this property at all, So Daniel
suggested me to remove that property too.
And that brings me to the other point. At least i915 will simply
override the mode's aspect ration with the property. So this looks like
a big no-op for now on i915.
Yes, This is a bug in I915. When I published the first version of this
series, I had one patch, which was overriding the value only when the
property is set.
This should be the right case. And then Daniel suggested to remove the
property all together (and it makes sense as we have proper aspect
ratios in mode information
itself) So I kept that patch separate, to be merged separately.
Yeah, removing the property entirely seems like an OKish solution since
userspace can just stuff that information into the mode flags instead.
The only slight concern is that someone's setup might depend on the
property, and now we're removing it.
Thanks, will send the patch for it soon, adding you in the mail chain.
    It's looking like we might need a new
propetty value to differentiate between "auto" and "none" for real.
Now we have the exact aspect ratio given by monitor EDID, so IMHO it
would be better if we can just have real aspect.
Well, "real" isn't quite the right term. It's still a user specified
thing, which means the user can ask for somehting the display didn't
even advertise. Which is fine as such, however since the AVI infoframe
lacks the capability to transmit these new aspect ratios we have a bit
of problem on our hands if the user asks for something we can't even
tell the display to do. I guess we would just need to return an error
to the user in that case.
The current implementation which we have in andoroid, is hardware
composer shows the whole mode in the list like:
- 1920x1080@60 16:9    /* From CEA block of EDID */
- 1920x1080@60 0:0        /* From detailed descriptor block of EDID */
- 1280x720@60 4:3          /* From CEA block of EDID */
These mode is the connector->probed_modes which we populated while
parsing the EDID.
Now, when user selects the mode, its a complete set of resolution +
refresh rate + aspect ratio, so user can only pick what
we are showing to it. In this case, there is no option which we cant

Do you think that there would be some other model of use case, where we
can mix something among these?
You can't assume the user just picks the mode off the list. They can
stuff whatever random garbage into the mode if they wish.

I agree, there can be a use case model.

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