linux-kernel - [PATCH 1/7] drm/sun4i: backend: Fix probe failure with multiple backends

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Date:   Fri,  6 Nov 2020 16:14:05 +0100
From:   Maxime Ripard <maxime@...no.tech>
To:     Daniel Vetter <daniel.vetter@...el.com>,
        David Airlie <airlied@...ux.ie>, Christoph Hellwig <hch@....de>
Cc:     Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
        Yong Deng <yong.deng@...ewell.com>,
        linux-arm-kernel@...ts.infradead.org,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, devel@...verdev.osuosl.org,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Maxime Ripard <maxime@...no.tech>,
        Robin Murphy <robin.murphy@....com>,
        Hans Verkuil <hverkuil@...all.nl>
Subject: [PATCH 1/7] drm/sun4i: backend: Fix probe failure with multiple backends

Commit e0d072782c73 ("dma-mapping: introduce DMA range map, supplanting
dma_pfn_offset") introduced a regression in our code since the second
backed to probe will now get -EINVAL back from dma_direct_set_offset and
will prevent the entire DRM device from probing.

Ignore -EINVAL as a temporary measure to get it back working, before
removing that call entirely.

Fixes: e0d072782c73 ("dma-mapping: introduce DMA range map, supplanting dma_pfn_offset")
Signed-off-by: Maxime Ripard <maxime@...no.tech>
---
 drivers/gpu/drm/sun4i/sun4i_backend.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c b/drivers/gpu/drm/sun4i/sun4i_backend.c
index 77497b45f9a2..55960cbb1019 100644
--- a/drivers/gpu/drm/sun4i/sun4i_backend.c
+++ b/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;
 	}
 
-- 
2.28.0