[PATCH] drm/sharp-memory: Do not access GEM-DMA vaddr directly

[Thomas Zimmermann]

ping for a review

Am 27.06.25 um 17:23 schrieb Thomas Zimmermann:
> Use DRM's shadow-plane helper to map and access the GEM object's buffer
> within kernel address space. Encasulates the vmap logic in the GEM-DMA
> helpers.
>
> The sharp-memory driver currently reads the vaddr field from the GME
> buffer object directly. This only works because GEM code 'automagically'
> sets vaddr.
>
> Shadow-plane helpers perform the same steps, but with correct abstraction
> behind drm_gem_vmap(). The shadow-plane state provides the buffer address
> in kernel address space and the format-conversion state.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
> ---
>   drivers/gpu/drm/tiny/sharp-memory.c | 27 +++++++++++++--------------
>   1 file changed, 13 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/tiny/sharp-memory.c b/drivers/gpu/drm/tiny/sharp-memory.c
> index 03d2850310c4..64272cd0f6e2 100644
> --- a/drivers/gpu/drm/tiny/sharp-memory.c
> +++ b/drivers/gpu/drm/tiny/sharp-memory.c
> @@ -126,28 +126,28 @@ static inline void sharp_memory_set_tx_buffer_addresses(u8 *buffer,
>   
>   static void sharp_memory_set_tx_buffer_data(u8 *buffer,
>   					    struct drm_framebuffer *fb,
> +					    const struct iosys_map *vmap,
>   					    struct drm_rect clip,
>   					    u32 pitch,
>   					    struct drm_format_conv_state *fmtcnv_state)
>   {
>   	int ret;
> -	struct iosys_map dst, vmap;
> -	struct drm_gem_dma_object *dma_obj = drm_fb_dma_get_gem_obj(fb, 0);
> +	struct iosys_map dst;
>   
>   	ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);
>   	if (ret)
>   		return;
>   
>   	iosys_map_set_vaddr(&dst, buffer);
> -	iosys_map_set_vaddr(&vmap, dma_obj->vaddr);
>   
> -	drm_fb_xrgb8888_to_mono(&dst, &pitch, &vmap, fb, &clip, fmtcnv_state);
> +	drm_fb_xrgb8888_to_mono(&dst, &pitch, vmap, fb, &clip, fmtcnv_state);
>   
>   	drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
>   }
>   
>   static int sharp_memory_update_display(struct sharp_memory_device *smd,
>   				       struct drm_framebuffer *fb,
> +				       const struct iosys_map *vmap,
>   				       struct drm_rect clip,
>   				       struct drm_format_conv_state *fmtcnv_state)
>   {
> @@ -163,7 +163,7 @@ static int sharp_memory_update_display(struct sharp_memory_device *smd,
>   	sharp_memory_set_tx_buffer_mode(&tx_buffer[0],
>   					SHARP_MEMORY_DISPLAY_UPDATE_MODE, vcom);
>   	sharp_memory_set_tx_buffer_addresses(&tx_buffer[1], clip, pitch);
> -	sharp_memory_set_tx_buffer_data(&tx_buffer[2], fb, clip, pitch, fmtcnv_state);
> +	sharp_memory_set_tx_buffer_data(&tx_buffer[2], fb, vmap, clip, pitch, fmtcnv_state);
>   
>   	ret = sharp_memory_spi_write(smd->spi, tx_buffer, tx_buffer_size);
>   
> @@ -206,7 +206,8 @@ static int sharp_memory_clear_display(struct sharp_memory_device *smd)
>   	return ret;
>   }
>   
> -static void sharp_memory_fb_dirty(struct drm_framebuffer *fb, struct drm_rect *rect,
> +static void sharp_memory_fb_dirty(struct drm_framebuffer *fb, const struct iosys_map *vmap,
> +				  struct drm_rect *rect,
>   				  struct drm_format_conv_state *fmtconv_state)
>   {
>   	struct drm_rect clip;
> @@ -218,7 +219,7 @@ static void sharp_memory_fb_dirty(struct drm_framebuffer *fb, struct drm_rect *r
>   	clip.y1 = rect->y1;
>   	clip.y2 = rect->y2;
>   
> -	sharp_memory_update_display(smd, fb, clip, fmtconv_state);
> +	sharp_memory_update_display(smd, fb, vmap, clip, fmtconv_state);
>   }
>   
>   static int sharp_memory_plane_atomic_check(struct drm_plane *plane,
> @@ -242,7 +243,7 @@ static void sharp_memory_plane_atomic_update(struct drm_plane *plane,
>   {
>   	struct drm_plane_state *old_state = drm_atomic_get_old_plane_state(state, plane);
>   	struct drm_plane_state *plane_state = plane->state;
> -	struct drm_format_conv_state fmtcnv_state = DRM_FORMAT_CONV_STATE_INIT;
> +	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
>   	struct sharp_memory_device *smd;
>   	struct drm_rect rect;
>   
> @@ -251,15 +252,15 @@ static void sharp_memory_plane_atomic_update(struct drm_plane *plane,
>   		return;
>   
>   	if (drm_atomic_helper_damage_merged(old_state, plane_state, &rect))
> -		sharp_memory_fb_dirty(plane_state->fb, &rect, &fmtcnv_state);
> -
> -	drm_format_conv_state_release(&fmtcnv_state);
> +		sharp_memory_fb_dirty(plane_state->fb, shadow_plane_state->data,
> +				      &rect, &shadow_plane_state->fmtcnv_state);
>   }
>   
>   static const struct drm_plane_helper_funcs sharp_memory_plane_helper_funcs = {
>   	.prepare_fb = drm_gem_plane_helper_prepare_fb,
>   	.atomic_check = sharp_memory_plane_atomic_check,
>   	.atomic_update = sharp_memory_plane_atomic_update,
> +	DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
>   };
>   
>   static bool sharp_memory_format_mod_supported(struct drm_plane *plane,
> @@ -273,9 +274,7 @@ static const struct drm_plane_funcs sharp_memory_plane_funcs = {
>   	.update_plane = drm_atomic_helper_update_plane,
>   	.disable_plane = drm_atomic_helper_disable_plane,
>   	.destroy = drm_plane_cleanup,
> -	.reset = drm_atomic_helper_plane_reset,
> -	.atomic_duplicate_state	= drm_atomic_helper_plane_duplicate_state,
> -	.atomic_destroy_state = drm_atomic_helper_plane_destroy_state,
> +	DRM_GEM_SHADOW_PLANE_FUNCS,
>   	.format_mod_supported = sharp_memory_format_mod_supported,
>   };
>   

-- 
--
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)