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