[PATCH] drm/amdgpu: Ensure that the modifier requested is supported by plane.

[Mark Yacoub]

On Tue, Mar 23, 2021 at 11:02 AM Alex Deucher <alexdeucher at gmail.com> wrote:
>
> On Wed, Mar 10, 2021 at 11:15 AM Mark Yacoub <markyacoub at chromium.org> wrote:
> >
> > From: Mark Yacoub <markyacoub at google.com>
> >
> > On initializing the framebuffer, call drm_any_plane_has_format to do a
> > check if the modifier is supported. drm_any_plane_has_format calls
> > dm_plane_format_mod_supported which is extended to validate that the
> > modifier is on the list of the plane's supported modifiers.
> >
> > The bug was caught using igt-gpu-tools test: kms_addfb_basic.addfb25-bad-modifier
> >
> > Tested on ChromeOS Zork by turning on the display, running an overlay
> > test, and running a YT video.
> >
> > Cc: Alex Deucher <alexander.deucher at amd.com>
> > Cc: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
> > Signed-off-by: default avatarMark Yacoub <markyacoub at chromium.org>
>
> I'm not an expert with modifiers yet.  Will this break chips which
> don't currently support modifiers?
No it shouldn't. When you don't support modifiers yet, your will
default to Linear Modifier (DRM_FORMAT_MOD_LINEAR),
which is later checked in amdgpu_dm.c::dm_plane_format_mod_supported()
    /*
    * We always have to allow this modifier, because core DRM still
    * checks LINEAR support if userspace does not provide modifiers.
    */
    if (modifier == DRM_FORMAT_MOD_LINEAR)
        return true;

>
> Alex
>
>
> > ---
> >  drivers/gpu/drm/amd/amdgpu/amdgpu_display.c       | 13 +++++++++++++
> >  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |  9 +++++++++
> >  2 files changed, 22 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> > index afa5f8ad0f563..a947b5aa420d2 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> > @@ -908,6 +908,19 @@ int amdgpu_display_gem_fb_verify_and_init(
> >                                          &amdgpu_fb_funcs);
> >         if (ret)
> >                 goto err;
> > +       /* Verify that the modifier is supported. */
> > +       if (!drm_any_plane_has_format(dev, mode_cmd->pixel_format,
> > +                                     mode_cmd->modifier[0])) {
> > +               struct drm_format_name_buf format_name;
> > +               drm_dbg_kms(dev,
> > +                           "unsupported pixel format %s / modifier 0x%llx\n",
> > +                           drm_get_format_name(mode_cmd->pixel_format,
> > +                                               &format_name),
> > +                           mode_cmd->modifier[0]);
> > +
> > +               ret = -EINVAL;
> > +               goto err;
> > +       }
> >
> >         ret = amdgpu_display_framebuffer_init(dev, rfb, mode_cmd, obj);
> >         if (ret)
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > index 961abf1cf040c..21314024a83ce 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > @@ -3939,6 +3939,7 @@ static bool dm_plane_format_mod_supported(struct drm_plane *plane,
> >  {
> >         struct amdgpu_device *adev = drm_to_adev(plane->dev);
> >         const struct drm_format_info *info = drm_format_info(format);
> > +       int i;
> >
> >         enum dm_micro_swizzle microtile = modifier_gfx9_swizzle_mode(modifier) & 3;
> >
> > @@ -3952,6 +3953,14 @@ static bool dm_plane_format_mod_supported(struct drm_plane *plane,
> >         if (modifier == DRM_FORMAT_MOD_LINEAR)
> >                 return true;
> >
> > +       /* Check that the modifier is on the list of the plane's supported modifiers. */
> > +       for (i = 0; i < plane->modifier_count; i++) {
> > +               if (modifier == plane->modifiers[i])
> > +                       break;
> > +       }
> > +       if (i == plane->modifier_count)
> > +               return false;
> > +
> >         /*
> >          * The arbitrary tiling support for multiplane formats has not been hooked
> >          * up.
> > --
> > 2.30.1.766.gb4fecdf3b7-goog
> >
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel