From 131b4d4f22cc2af5af2b302b85a937a32973a139 Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Mon, 16 May 2022 15:43:37 +0200 Subject: [PATCH] drm/mgag200: Acquire I/O lock while reading EDID [ Upstream commit 5913ab941d6ea782e841234c76958c6872ea752d ] DDC operation conflicts with concurrent mode setting. Acquire the driver's I/O lock in get_modes to prevent this. This change should have been part of commit 931e3f3a0e99 ("drm/mgag200: Protect concurrent access to I/O registers with lock"), but apparently got lost somewhere. v3: * fix commit message to say 'drm/mgag200' (Jocelyn) Signed-off-by: Thomas Zimmermann Fixes: 931e3f3a0e99 ("drm/mgag200: Protect concurrent access to I/O registers with lock") Reviewed-by: Jocelyn Falempe Tested-by: Jocelyn Falempe Cc: Thomas Zimmermann Cc: Jocelyn Falempe Cc: Daniel Vetter Cc: Dave Airlie Cc: dri-devel@lists.freedesktop.org Link: https://patchwork.freedesktop.org/patch/msgid/20220516134343.6085-2-tzimmermann@suse.de Signed-off-by: Sasha Levin --- drivers/gpu/drm/mgag200/mgag200_mode.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c index abde7655477d..4ad8d62c5631 100644 --- a/drivers/gpu/drm/mgag200/mgag200_mode.c +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c @@ -667,16 +667,26 @@ static void mgag200_disable_display(struct mga_device *mdev) static int mga_vga_get_modes(struct drm_connector *connector) { + struct mga_device *mdev = to_mga_device(connector->dev); struct mga_connector *mga_connector = to_mga_connector(connector); struct edid *edid; int ret = 0; + /* + * Protect access to I/O registers from concurrent modesetting + * by acquiring the I/O-register lock. + */ + mutex_lock(&mdev->rmmio_lock); + edid = drm_get_edid(connector, &mga_connector->i2c->adapter); if (edid) { drm_connector_update_edid_property(connector, edid); ret = drm_add_edid_modes(connector, edid); kfree(edid); } + + mutex_unlock(&mdev->rmmio_lock); + return ret; }