Re: [PATCH v2] drm/gma500: Create the primary plane in the driver

[Patrik Jakobsson]

On Thu, Sep 3, 2026 at 9:12 AM <oushixiong1025@xxxxxxx> wrote:
>
> From: Shixiong Ou <oushixiong@xxxxxxxxxx>
>
> drm_crtc_init() creates the primary plane from a fixed format list
> that includes ARGB8888. The display engine programs the primary plane
> with DISPPLANE_32BPP_NO_ALPHA, so it does not support per-pixel alpha
> and must not advertise alpha formats. Since commit 860e748bddcc
> ("drm: ensure blend mode supported if pixel format with alpha exposed"),
> drm_mode_config_validate() warns about this at probe time.
>
> Replace drm_crtc_init() with a driver-owned primary plane that
> advertises only XRGB8888. The plane is allocated by
> drmm_universal_plane_alloc() and the "pixel blend mode" property is
> not needed because no format with alpha is exposed.
>
> Signed-off-by: Shixiong Ou <oushixiong@xxxxxxxxxx>

Thanks for the patch. Applied to drm-misc-next

-Patrik

> ---
> v1->v2:
>   - Open-code DRM_PLANE_NON_ATOMIC_FUNCS without .destroy, which
>     drmm_universal_plane_alloc() rejects
>   - Use drmm_universal_plane_alloc() for automatic cleanup
>   - Move the formats comment above the array
>
>  drivers/gpu/drm/gma500/psb_intel_display.c | 34 +++++++++++++++++++++-
>  1 file changed, 33 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/gma500/psb_intel_display.c b/drivers/gpu/drm/gma500/psb_intel_display.c
> index 0df75a4a7739..f79484b9d593 100644
> --- a/drivers/gpu/drm/gma500/psb_intel_display.c
> +++ b/drivers/gpu/drm/gma500/psb_intel_display.c
> @@ -9,8 +9,11 @@
>  #include <linux/delay.h>
>  #include <linux/i2c.h>
>
> +#include <drm/drm_fourcc.h>
>  #include <drm/drm_modeset_helper.h>
>  #include <drm/drm_modeset_helper_vtables.h>
> +#include <drm/drm_plane.h>
> +#include <drm/drm_plane_helper.h>
>  #include <drm/drm_print.h>
>
>  #include "framebuffer.h"
> @@ -471,11 +474,25 @@ static void psb_intel_cursor_init(struct drm_device *dev,
>         REG_WRITE(base[gma_crtc->pipe], 0);
>  }
>
> +/*
> + * The display engine programs the primary plane with
> + * DISPPLANE_32BPP_NO_ALPHA, so no formats with alpha.
> + */
> +static const uint32_t gma_primary_formats[] = {
> +       DRM_FORMAT_XRGB8888,
> +};
> +
> +static const struct drm_plane_funcs gma_primary_plane_funcs = {
> +       .update_plane = drm_plane_helper_update_primary,
> +       .disable_plane = drm_plane_helper_disable_primary,
> +};
> +
>  void psb_intel_crtc_init(struct drm_device *dev, int pipe,
>                      struct psb_intel_mode_device *mode_dev)
>  {
>         struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
>         struct gma_crtc *gma_crtc;
> +       struct drm_plane *primary;
>         int i;
>
>         /* We allocate a extra array of drm_connector pointers
> @@ -494,7 +511,17 @@ void psb_intel_crtc_init(struct drm_device *dev, int pipe,
>                 return;
>         }
>
> -       drm_crtc_init(dev, &gma_crtc->base, &gma_crtc_funcs);
> +       primary = drmm_universal_plane_alloc(dev, struct drm_plane, dev, 0,
> +                                            &gma_primary_plane_funcs,
> +                                            gma_primary_formats,
> +                                            ARRAY_SIZE(gma_primary_formats),
> +                                            NULL, DRM_PLANE_TYPE_PRIMARY, NULL);
> +       if (IS_ERR(primary))
> +               goto err_free_crtc;
> +
> +       if (drm_crtc_init_with_planes(dev, &gma_crtc->base, primary, NULL,
> +                                     &gma_crtc_funcs, NULL))
> +               goto err_free_crtc;
>
>         /* Set the CRTC clock functions from chip specific data */
>         gma_crtc->clock_funcs = dev_priv->ops->clock_funcs;
> @@ -524,6 +551,11 @@ void psb_intel_crtc_init(struct drm_device *dev, int pipe,
>
>         /* Set to true so that the pipe is forced off on initial config. */
>         gma_crtc->active = true;
> +       return;
> +
> +err_free_crtc:
> +       kfree(gma_crtc->crtc_state);
> +       kfree(gma_crtc);
>  }
>
>  struct drm_crtc *psb_intel_get_crtc_from_pipe(struct drm_device *dev, int pipe)
> --
> 2.25.1
>
>
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