From: Brian Norris briannorris@chromium.org
commit 8fb6c44fe8468f92ac7b8bbfcca4404a4e88645f upstream.
If the display is not enable()d, then we aren't holding a runtime PM reference here. Thus, it's easy to accidentally cause a hang, if user space is poking around at /dev/drm_dp_aux0 at the "wrong" time.
Let's get a runtime PM reference, and check that we "see" the panel. Don't force any panel power-up, etc., because that can be intrusive, and that's not what other drivers do (see drivers/gpu/drm/bridge/ti-sn65dsi86.c and drivers/gpu/drm/bridge/parade-ps8640.c.)
Fixes: 0d97ad03f422 ("drm/bridge: analogix_dp: Remove duplicated code") Cc: stable@vger.kernel.org Cc: Tomeu Vizoso tomeu.vizoso@collabora.com Signed-off-by: Brian Norris briannorris@chromium.org Reviewed-by: Douglas Anderson dianders@chromium.org Signed-off-by: Douglas Anderson dianders@chromium.org Link: https://patchwork.freedesktop.org/patch/msgid/20220301181107.v4.1.I773a08785... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c @@ -1514,8 +1514,19 @@ static ssize_t analogix_dpaux_transfer(s struct drm_dp_aux_msg *msg) { struct analogix_dp_device *dp = to_dp(aux); + int ret;
- return analogix_dp_transfer(dp, msg); + pm_runtime_get_sync(dp->dev); + + ret = analogix_dp_detect_hpd(dp); + if (ret) + goto out; + + ret = analogix_dp_transfer(dp, msg); +out: + pm_runtime_put(dp->dev); + + return ret; }
struct analogix_dp_device *