Merge tag 'drm/sun4i-dma-fix-pull-request' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/mripard/linux into drm-misc-fixes

Fix for drm/sun4i shared with arm-soc

This patch is a preliminary fix that will conflict with subsequent work merged
through arm-soc.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>

# gpg: Signature made Wed 18 Nov 2020 09:51:53 AM CET
# gpg:                using EDDSA key 5C1337A45ECA9AEB89060E9EE3EF0D6F671851C5
# gpg: Good signature from "Maxime Ripard <maxime.ripard@anandra.org>" [unknown]
# gpg:                 aka "Maxime Ripard <mripard@kernel.org>" [unknown]
# gpg:                 aka "Maxime Ripard (Work Address) <maxime.ripard@bootlin.com>" [unknown]
# gpg:                 aka "Maxime Ripard (Work Address) <maxime@bootlin.com>" [unknown]
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: BE56 75C3 7E81 8C8B 5764  241C 254B CFC5 6BF6 CE8D
#      Subkey fingerprint: 5C13 37A4 5ECA 9AEB 8906  0E9E E3EF 0D6F 6718 51C5
From: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20201118090455.sznrgpduuytlc22k@gilmour.lan

Author: mripard

drivers/gpu/drm/sun4i/sun4i_backend.c

@@ -814,9 +814,15 @@ static int sun4i_backend_bind(struct device *dev, struct device *master,
 		 *
 		 * XXX(hch): this has no business in a driver and needs to move
 		 * to the device tree.
+		 *
+		 * If we have two subsequent calls to dma_direct_set_offset
+		 * returns -EINVAL. Unfortunately, this happens when we have two
+		 * backends in the system, and will result in the driver
+		 * reporting an error while it has been setup properly before.
+		 * Ignore EINVAL, but it should really be removed eventually.
 		 */
 		ret = dma_direct_set_offset(drm->dev, PHYS_OFFSET, 0, SZ_4G);
-		if (ret)
+		if (ret && ret != -EINVAL)
 			return ret;
 	}