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 <tzimmerm...@suse.de>
Signed-off-by: Javier Martinez Canillas <javi...@redhat.com>
---

 drivers/gpu/drm/solomon/ssd130x.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/solomon/ssd130x.c 
b/drivers/gpu/drm/solomon/ssd130x.c
index a537692100d1..bc41a5ae810a 100644
--- 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;
-- 
2.37.3

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