On 2021-10-11 11:16, Simon Ser wrote:
> Commit ddab8bd788f5 ("drm/amd/display: Fix two cursor duplication when
> using overlay") changed the atomic validation code to forbid the
> overlay plane from being used if it doesn't cover the whole CRTC. The
> motivation is that ChromeOS uses the atomic API for everything except
> the cursor plane (which uses the legacy API). Thus amdgpu must always
> be prepared to enable/disable/move the cursor plane at any time without
> failing (or else ChromeOS will trip over).
>
> As discussed in [1], there's no reason why the ChromeOS limitation
> should prevent other fully atomic users from taking advantage of the
> overlay plane. Let's limit the check to ChromeOS.
>
> v4: fix ChromeOS detection (Harry)
>
> v5: fix conflict with linux-next
>
> [1]: https://lore.kernel.org/amd-gfx/JIQ_93_cHcshiIDsrMU1huBzx9P9LVQxucx8hQArpQu7Wk5DrCl_vTXj_Q20m_L-8C8A5dSpNcSJ8ehfcCrsQpfB5QG_Spn14EYkH9chtg0=@emersion.fr/>>
> Signed-off-by: Simon Ser <contact@xxxxxxxxxxx>
> Cc: Alex Deucher <alexander.deucher@xxxxxxx>
> Cc: Harry Wentland <hwentlan@xxxxxxx>
> Cc: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx>
> Cc: Bas Nieuwenhuizen <bas@xxxxxxxxxxxxxxxxxxx>
> Cc: Rodrigo Siqueira <Rodrigo.Siqueira@xxxxxxx>
> Cc: Sean Paul <seanpaul@xxxxxxxxxxxx>
> Fixes: ddab8bd788f5 ("drm/amd/display: Fix two cursor duplication when using overlay")
Reviewed-by: Harry Wentland <harry.wentland@xxxxxxx>
Harry
> ---
> .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 29 +++++++++++++++++++
> 1 file changed, 29 insertions(+)
>
> 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 f35561b5a465..2eeda1fec506 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -10594,6 +10594,31 @@ static int add_affected_mst_dsc_crtcs(struct drm_atomic_state *state, struct drm
> }
> #endif
>
> +static bool is_chromeos(void)
> +{
> + struct mm_struct *mm = current->mm;
> + struct file *exe_file;
> + bool ret;
> +
> + /* ChromeOS renames its thread to DrmThread. Also check the executable
> + * name. */
> + if (strcmp(current->comm, "DrmThread") != 0 || !mm)
> + return false;
> +
> + rcu_read_lock();
> + exe_file = rcu_dereference(mm->exe_file);
> + if (exe_file && !get_file_rcu(exe_file))
> + exe_file = NULL;
> + rcu_read_unlock();
> +
> + if (!exe_file)
> + return false;
> + ret = strcmp(exe_file->f_path.dentry->d_name.name, "chrome") == 0;
> + fput(exe_file);
> +
> + return ret;
> +}
> +
> static int validate_overlay(struct drm_atomic_state *state)
> {
> int i;
> @@ -10601,6 +10626,10 @@ static int validate_overlay(struct drm_atomic_state *state)
> struct drm_plane_state *new_plane_state;
> struct drm_plane_state *primary_state, *overlay_state = NULL;
>
> + /* This is a workaround for ChromeOS only */
> + if (!is_chromeos())
> + return 0;
> +
> /* Check if primary plane is contained inside overlay */
> for_each_new_plane_in_state_reverse(state, plane, new_plane_state, i) {
> if (plane->type == DRM_PLANE_TYPE_OVERLAY) {
>
