| Message ID | 20220217144136.v3.1.I773a08785666ebb236917b0c8e6c05e3de471e75@changeid (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3,1/2] drm/bridge: analogix_dp: Grab runtime PM reference for DP-AUX | expand |
Hi, On Thu, Feb 17, 2022 at 2:42 PM Brian Norris <briannorris@chromium.org> wrote: > > 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> > --- > > Changes in v3: > - Avoid panel power-up; just check for HPD state, and let the rest > happen "as-is" (e.g., time out, if the caller hasn't prepared things > properly) > > Changes in v2: > - Fix spelling in Subject > - DRM_DEV_ERROR() -> drm_err() > - Propagate errors from un-analogix_dp_prepare_panel() > > drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) Reviewed-by: Douglas Anderson <dianders@chromium.org> -Doug
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c index b7d2e4449cfa..16be279aed2c 100644 --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c @@ -1632,8 +1632,19 @@ static ssize_t analogix_dpaux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg) { struct analogix_dp_device *dp = to_dp(aux); + int ret; + + pm_runtime_get_sync(dp->dev); + + ret = analogix_dp_detect_hpd(dp); + if (ret) + goto out; - return analogix_dp_transfer(dp, msg); + ret = analogix_dp_transfer(dp, msg); +out: + pm_runtime_put(dp->dev); + + return ret; } struct analogix_dp_device *
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> --- Changes in v3: - Avoid panel power-up; just check for HPD state, and let the rest happen "as-is" (e.g., time out, if the caller hasn't prepared things properly) Changes in v2: - Fix spelling in Subject - DRM_DEV_ERROR() -> drm_err() - Propagate errors from un-analogix_dp_prepare_panel() drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)