This is a note to let you know that I've just added the patch titled
drm/bridge: sii902x: Fix probing race issue
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-bridge-sii902x-fix-probing-race-issue.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 172d2b8aaf68ce7a1a872bd5c21ce9dbb00f5435
Author: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
Date: Wed Jan 3 15:31:07 2024 +0200
drm/bridge: sii902x: Fix probing race issue
[ Upstream commit 08ac6f132dd77e40f786d8af51140c96c6d739c9 ]
A null pointer dereference crash has been observed rarely on TI
platforms using sii9022 bridge:
[ 53.271356] sii902x_get_edid+0x34/0x70 [sii902x]
[ 53.276066] sii902x_bridge_get_edid+0x14/0x20 [sii902x]
[ 53.281381] drm_bridge_get_edid+0x20/0x34 [drm]
[ 53.286305] drm_bridge_connector_get_modes+0x8c/0xcc [drm_kms_helper]
[ 53.292955] drm_helper_probe_single_connector_modes+0x190/0x538 [drm_kms_helper]
[ 53.300510] drm_client_modeset_probe+0x1f0/0xbd4 [drm]
[ 53.305958] __drm_fb_helper_initial_config_and_unlock+0x50/0x510 [drm_kms_helper]
[ 53.313611] drm_fb_helper_initial_config+0x48/0x58 [drm_kms_helper]
[ 53.320039] drm_fbdev_dma_client_hotplug+0x84/0xd4 [drm_dma_helper]
[ 53.326401] drm_client_register+0x5c/0xa0 [drm]
[ 53.331216] drm_fbdev_dma_setup+0xc8/0x13c [drm_dma_helper]
[ 53.336881] tidss_probe+0x128/0x264 [tidss]
[ 53.341174] platform_probe+0x68/0xc4
[ 53.344841] really_probe+0x188/0x3c4
[ 53.348501] __driver_probe_device+0x7c/0x16c
[ 53.352854] driver_probe_device+0x3c/0x10c
[ 53.357033] __device_attach_driver+0xbc/0x158
[ 53.361472] bus_for_each_drv+0x88/0xe8
[ 53.365303] __device_attach+0xa0/0x1b4
[ 53.369135] device_initial_probe+0x14/0x20
[ 53.373314] bus_probe_device+0xb0/0xb4
[ 53.377145] deferred_probe_work_func+0xcc/0x124
[ 53.381757] process_one_work+0x1f0/0x518
[ 53.385770] worker_thread+0x1e8/0x3dc
[ 53.389519] kthread+0x11c/0x120
[ 53.392750] ret_from_fork+0x10/0x20
The issue here is as follows:
- tidss probes, but is deferred as sii902x is still missing.
- sii902x starts probing and enters sii902x_init().
- sii902x calls drm_bridge_add(). Now the sii902x bridge is ready from
DRM's perspective.
- sii902x calls sii902x_audio_codec_init() and
platform_device_register_data()
- The registration of the audio platform device causes probing of the
deferred devices.
- tidss probes, which eventually causes sii902x_bridge_get_edid() to be
called.
- sii902x_bridge_get_edid() tries to use the i2c to read the edid.
However, the sii902x driver has not set up the i2c part yet, leading
to the crash.
Fix this by moving the drm_bridge_add() to the end of the
sii902x_init(), which is also at the very end of sii902x_probe().
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
Fixes: 21d808405fe4 ("drm/bridge/sii902x: Fix EDID readback")
Acked-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240103-si902x-fixes-v1-1-b9fd3e448411@xxxxxxxxxxxxxxxx
Signed-off-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20240103-si902x-fixes-v1-1-b9fd3e448411@xxxxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/bridge/sii902x.c b/drivers/gpu/drm/bridge/sii902x.c
index f6e8b401069b..f648d686eb37 100644
--- a/drivers/gpu/drm/bridge/sii902x.c
+++ b/drivers/gpu/drm/bridge/sii902x.c
@@ -1040,16 +1040,6 @@ static int sii902x_init(struct sii902x *sii902x)
return ret;
}
- sii902x->bridge.funcs = &sii902x_bridge_funcs;
- sii902x->bridge.of_node = dev->of_node;
- sii902x->bridge.timings = &default_sii902x_timings;
- sii902x->bridge.ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID;
-
- if (sii902x->i2c->irq > 0)
- sii902x->bridge.ops |= DRM_BRIDGE_OP_HPD;
-
- drm_bridge_add(&sii902x->bridge);
-
sii902x_audio_codec_init(sii902x, dev);
i2c_set_clientdata(sii902x->i2c, sii902x);
@@ -1062,7 +1052,21 @@ static int sii902x_init(struct sii902x *sii902x)
return -ENOMEM;
sii902x->i2cmux->priv = sii902x;
- return i2c_mux_add_adapter(sii902x->i2cmux, 0, 0, 0);
+ ret = i2c_mux_add_adapter(sii902x->i2cmux, 0, 0, 0);
+ if (ret)
+ return ret;
+
+ sii902x->bridge.funcs = &sii902x_bridge_funcs;
+ sii902x->bridge.of_node = dev->of_node;
+ sii902x->bridge.timings = &default_sii902x_timings;
+ sii902x->bridge.ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID;
+
+ if (sii902x->i2c->irq > 0)
+ sii902x->bridge.ops |= DRM_BRIDGE_OP_HPD;
+
+ drm_bridge_add(&sii902x->bridge);
+
+ return 0;
}
static int sii902x_probe(struct i2c_client *client,
@@ -1130,12 +1134,11 @@ static int sii902x_probe(struct i2c_client *client,
}
static void sii902x_remove(struct i2c_client *client)
-
{
struct sii902x *sii902x = i2c_get_clientdata(client);
- i2c_mux_del_adapters(sii902x->i2cmux);
drm_bridge_remove(&sii902x->bridge);
+ i2c_mux_del_adapters(sii902x->i2cmux);
}
static const struct of_device_id sii902x_dt_ids[] = {
