From 208a445d74288cb4afd54b256782e72dfb4d2c7c Mon Sep 17 00:00:00 2001
From: Thomas Zimmermann <tzimmermann@suse.de>
Date: Mon, 16 May 2022 15:43:37 +0200
Subject: drm/mgag200: Acquire I/O lock while reading EDID
Git-commit: 5913ab941d6ea782e841234c76958c6872ea752d
Patch-mainline: v6.0-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225 jsc#PED-2849
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 <tzimmermann@suse.de>
Fixes: 931e3f3a0e99 ("drm/mgag200: Protect concurrent access to I/O registers with lock")
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Tested-by: Jocelyn Falempe <jfalempe@redhat.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Jocelyn Falempe <jfalempe@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dave Airlie <airlied@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Link: https://patchwork.freedesktop.org/patch/msgid/20220516134343.6085-2-tzimmermann@suse.de
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
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 73d5a4a42b3a..762b9657ae8d 100644
--- a/drivers/gpu/drm/mgag200/mgag200_mode.c
+++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
@@ -691,16 +691,26 @@ 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;
}
--
2.38.1