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

[Mark Yacoub]

On Tue, Mar 23, 2021 at 11:08 AM Bas Nieuwenhuizen
<bas at basnieuwenhuizen.nl> wrote:
>
>
>
> On Wed, Mar 10, 2021 at 5:14 PM 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>
>> ---
>>  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;
>> +       }
>
>
> Why is this needed?
This is the function that initiates the check for modifiers.
Inside it we call `plane->funcs->format_mod_supported` which is implemented as
dm_plane_format_mod_supported in amdgpu_dm.c, modified below as well.

>
>>
>>         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;
>> +
>
>
> This part seems fine by me.
>>
>>         /*
>>          * The arbitrary tiling support for multiplane formats has not been hooked
>>          * up.
>> --
>> 2.30.1.766.gb4fecdf3b7-goog
>>