Re: [PATCH v2 2/2] drm/vkms: set plane modifiers

[Simon Ser]

Overall looks good, but it is a bit repetitive to copy & paste this in all
drivers. It'd be nice to provide a core helper to do this, and then drivers
can just set format_mod_supported to the helper if they don't have more
involved logic. Thoughts?

See drm_plane_check_pixel_format, where the logic is already implemented.

Alternatively… We can just support a missing format_mod_supported in
create_in_format_blob. This sounds like this was the original intention of
db1689aa61bd ("drm: Create a format/modifier blob") and
drm_plane_check_pixel_format.

[PATCH v2 2/2] drm/vkms: set plane modifiers

[José Expósito]

Where no modifiers are exposed, usually linear modifier is assumed.
However, userspace code is starting to expect IN_FORMATS even when the
only supported modifiers are linear [1].

To avoid possible issues, explicitly set the DRM_FORMAT_MOD_LINEAR
modifier.

[1] 
https://gitlab.freedesktop.org/wayland/weston/-/merge_requests/599/diffs?commit_id=5aea1bc522f0874e6cc07f5120fbcf1736706536

Suggested-by: Chris Healy 
Signed-off-by: José Expósito 

---

v2: Implement format_mod_supported (Simon Ser)
---
 drivers/gpu/drm/vkms/vkms_plane.c | 34 ++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vkms/vkms_plane.c 
b/drivers/gpu/drm/vkms/vkms_plane.c
index 76a06dd92ac1..7e0d021494c3 100644
--- a/drivers/gpu/drm/vkms/vkms_plane.c
+++ b/drivers/gpu/drm/vkms/vkms_plane.c
@@ -20,6 +20,11 @@ static const u32 vkms_plane_formats[] = {
DRM_FORMAT_XRGB
 };
 
+static const u64 vkms_plane_modifiers[] = {
+   DRM_FORMAT_MOD_LINEAR,
+   DRM_FORMAT_MOD_INVALID
+};
+
 static struct drm_plane_state *
 vkms_plane_duplicate_state(struct drm_plane *plane)
 {
@@ -100,12 +105,39 @@ static void vkms_formats_for_plane_type(enum 
drm_plane_type type,
}
 }
 
+static bool vkms_format_mod_supported(struct drm_plane *plane, u32 format,
+ u64 modifier)
+{
+   bool modifier_found = false;
+   unsigned int i;
+   const u32 *formats;
+   int nformats;
+
+   for (i = 0; i < ARRAY_SIZE(vkms_plane_modifiers) - 1; i++) {
+   if (vkms_plane_modifiers[i] == modifier)
+   modifier_found = true;
+   }
+
+   if (!modifier_found)
+   return false;
+
+   vkms_formats_for_plane_type(plane->type, &formats, &nformats);
+
+   for (i = 0; i < nformats; i++) {
+   if (formats[i] == format)
+   return true;
+   }
+
+   return false;
+}
+
 static const struct drm_plane_funcs vkms_plane_funcs = {
.update_plane   = drm_atomic_helper_update_plane,
.disable_plane  = drm_atomic_helper_disable_plane,
.reset  = vkms_plane_reset,
.atomic_duplicate_state = vkms_plane_duplicate_state,
.atomic_destroy_state   = vkms_plane_destroy_state,
+   .format_mod_supported   = vkms_format_mod_supported,
 };
 
 static void vkms_plane_atomic_update(struct drm_plane *plane,
@@ -190,7 +222,7 @@ struct vkms_plane *vkms_plane_init(struct vkms_device 
*vkmsdev,
plane = drmm_universal_plane_alloc(dev, struct vkms_plane, base, 1 << 
index,
   &vkms_plane_funcs,
   formats, nformats,
-  NULL, type, NULL);
+  vkms_plane_modifiers, type, NULL);
if (IS_ERR(plane))
return plane;
 
-- 
2.25.1