Re: [PATCH v11 5/9] drm/fb_dma: Add generic get_scanout_buffer() for drm_panic

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

Hi

Am 28.03.24 um 13:03 schrieb Jocelyn Falempe:
> This was initialy done for imx6, but should work on most drivers
> using drm_fb_dma_helper.
>
> v8:
>   * Replace get_scanout_buffer() logic with drm_panic_set_buffer()
>     (Thomas Zimmermann)
>
> v9:
>   * go back to get_scanout_buffer()
>   * move get_scanout_buffer() to plane helper functions
>
> Signed-off-by: Jocelyn Falempe <jfalempe@xxxxxxxxxx>
> ---
>   drivers/gpu/drm/drm_fb_dma_helper.c | 47 +++++++++++++++++++++++++++++
>   include/drm/drm_fb_dma_helper.h     |  4 +++
>   2 files changed, 51 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_fb_dma_helper.c b/drivers/gpu/drm/drm_fb_dma_helper.c
> index 3b535ad1b07c..010327069ad4 100644
> --- a/drivers/gpu/drm/drm_fb_dma_helper.c
> +++ b/drivers/gpu/drm/drm_fb_dma_helper.c
> @@ -15,6 +15,7 @@
>   #include <drm/drm_framebuffer.h>
>   #include <drm/drm_gem_dma_helper.h>
>   #include <drm/drm_gem_framebuffer_helper.h>
> +#include <drm/drm_panic.h>
>   #include <drm/drm_plane.h>
>   #include <linux/dma-mapping.h>
>   #include <linux/module.h>
> @@ -148,3 +149,49 @@ void drm_fb_dma_sync_non_coherent(struct drm_device *drm,
>   	}
>   }
>   EXPORT_SYMBOL_GPL(drm_fb_dma_sync_non_coherent);
> +
> +#if defined(CONFIG_DRM_PANIC)

I would not bother with CONFIG_DRM_PANIC for now and make the helper 
generally available.

> +/**
> + * @plane: DRM primary plane
> + * @drm_scanout_buffer: scanout buffer for the panic handler
> + * Returns: 0 or negative error code
> + *
> + * Generic get_scanout_buffer() implementation, for drivers that uses the
> + * drm_fb_dma_helper.
> + */
> +int drm_panic_gem_get_scanout_buffer(struct drm_plane *plane,
> +				     struct drm_scanout_buffer *sb)

It's neither really a function for panic handling nor a GEM function. 
This helper needs to be called drm_fb_dma_get_scanout_buffer() IMHO.

> +{
> +	struct drm_gem_dma_object *dma_obj;
> +	struct drm_framebuffer *fb;
> +
> +	fb = plane->state->fb;
> +	/* Only support linear modifier */
> +	if (fb->modifier != DRM_FORMAT_MOD_LINEAR)
> +		return -ENODEV;
> +
> +	dma_obj = drm_fb_dma_get_gem_obj(fb, 0);
> +
> +	/* Buffer should be accessible from the CPU */
> +	if (dma_obj->base.import_attach)
> +		return -ENODEV;
> +
> +	/* Buffer should be already mapped to CPU */
> +	if (!dma_obj->vaddr)
> +		return -ENODEV;
> +
> +	iosys_map_set_vaddr(&sb->map, dma_obj->vaddr);
> +	sb->format = fb->format;
> +	sb->height = fb->height;
> +	sb->width = fb->width;
> +	sb->pitch = fb->pitches[0];
> +	return 0;
> +}
> +#else
> +int drm_panic_gem_get_scanout_buffer(struct drm_plane *plane,
> +				     struct drm_scanout_buffer *sb)
> +{
> +	return -ENODEV;
> +}
> +#endif
> +EXPORT_SYMBOL(drm_panic_gem_get_scanout_buffer);
> diff --git a/include/drm/drm_fb_dma_helper.h b/include/drm/drm_fb_dma_helper.h
> index d5e036c57801..61f24c2aba2f 100644
> --- a/include/drm/drm_fb_dma_helper.h
> +++ b/include/drm/drm_fb_dma_helper.h
> @@ -7,6 +7,7 @@
>   struct drm_device;
>   struct drm_framebuffer;
>   struct drm_plane_state;
> +struct drm_scanout_buffer;
>   
>   struct drm_gem_dma_object *drm_fb_dma_get_gem_obj(struct drm_framebuffer *fb,
>   	unsigned int plane);
> @@ -19,5 +20,8 @@ void drm_fb_dma_sync_non_coherent(struct drm_device *drm,
>   				  struct drm_plane_state *old_state,
>   				  struct drm_plane_state *state);
>   
> +int drm_panic_gem_get_scanout_buffer(struct drm_plane *plane,
> +				     struct drm_scanout_buffer *sb);
> +
>   #endif
>   

--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)