drm/ssd130x: Synchronize access to dma-buf imported GEM BOs

Synchronize CPU access to GEM BOs with other drivers when updating the
screen buffer. Imported DMA buffers might otherwise contain stale data.

Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20220927095249.1919385-1-javierm@redhat.com

diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
index a537692100d12d002f35ff9363797104247de01b..bc41a5ae810af0c68f00f70c96cee3d6fe7b2949 100644 (file)
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/drivers/gpu/drm/solomon/ssd130x.c
@@ -555,11 +555,18 @@ static int ssd130x_fb_blit_rect(struct drm_framebuffer *fb, const struct iosys_m
        if (!buf)
                return -ENOMEM;
 
+       ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);
+       if (ret)
+               goto out_free;
+
        iosys_map_set_vaddr(&dst, buf);
        drm_fb_xrgb8888_to_mono(&dst, &dst_pitch, vmap, fb, rect);
 
+       drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
+
        ssd130x_update_rect(ssd130x, buf, rect);
 
+out_free:
        kfree(buf);
 
        return ret;