Through log and waveform, we can see that there will be additional suspend/resume when booting. This timing does not meet the ps8640 spec. It seems that the delay of 500ms does not satisfied drm_panel_get_modes. I increased it to 900ms and it seems that this problem can be solved. To be safe, I'd just round up to a full 1000.

Signed-off-by: yangcong yangcong5@huaqin.corp-partner.google.com --- drivers/gpu/drm/bridge/parade-ps8640.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c index 0c7aab42b04f..0749fa628bfb 100644 --- a/drivers/gpu/drm/bridge/parade-ps8640.c +++ b/drivers/gpu/drm/bridge/parade-ps8640.c @@ -635,13 +635,13 @@ static int ps8640_probe(struct i2c_client *client) pm_runtime_enable(dev); /* * Powering on ps8640 takes ~300ms. To avoid wasting time on power - * cycling ps8640 too often, set autosuspend_delay to 500ms to ensure + * cycling ps8640 too often, set autosuspend_delay to 1000ms to ensure * the bridge wouldn't suspend in between each _aux_transfer_msg() call * during EDID read (~20ms in my experiment) and in between the last * _aux_transfer_msg() call during EDID read and the _pre_enable() call * (~100ms in my experiment). */ - pm_runtime_set_autosuspend_delay(dev, 500); + pm_runtime_set_autosuspend_delay(dev, 1000); pm_runtime_use_autosuspend(dev); pm_suspend_ignore_children(dev, true); ret = devm_add_action_or_reset(dev, ps8640_runtime_disable, dev);