Re: [Intel-gfx] [PATCH 1/2] drm/i915/display: Fix HPD short pulse handling for eDP

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Mar 10, 2022 at 12:05:17PM -0800, José Roberto de Souza wrote:
> Commit 13ea6db2cf24 ("drm/i915/edp: Ignore short pulse when panel
> powered off") completely broke short pulse handling for eDP as it is
> usually generated by sink when it is displaying image and there is
> some error or status that source needs to handle.
> 
> When power panel is enabled, this state is enough to power aux
> transactions and VDD override is disabled, so intel_pps_have_power()
> is always returning false causing short pulses to be ignored.

I think the times that we use the vdd override should be
limited to:
- aux transfers while the display off
- potentially short periods of time during the modeset sequence

So I guess what you're saying here is that during those times
some panel is triggering an IRQ_HPD which, if ignored, causes
some problem for us?

> 
> So here better naming this function that intends to check if aux
> lines are powered to avoid the endless cycle mentioned in the commit
> being fixed and fixing the check for what it is intended.
> 
> Fixes: 13ea6db2cf24 ("drm/i915/edp: Ignore short pulse when panel powered off")
> Cc: Anshuman Gupta <anshuman.gupta@intel.com>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Cc: Uma Shankar <uma.shankar@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp.c  | 2 +-
>  drivers/gpu/drm/i915/display/intel_pps.c | 4 ++--
>  drivers/gpu/drm/i915/display/intel_pps.h | 2 +-
>  3 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 619546441eae5..b029b064000d6 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -4867,7 +4867,7 @@ intel_dp_hpd_pulse(struct intel_digital_port *dig_port, bool long_hpd)
>  	struct intel_dp *intel_dp = &dig_port->dp;
>  
>  	if (dig_port->base.type == INTEL_OUTPUT_EDP &&
> -	    (long_hpd || !intel_pps_have_power(intel_dp))) {
> +	    (long_hpd || !intel_pps_have_vdd_power(intel_dp))) {
>  		/*
>  		 * vdd off can generate a long/short pulse on eDP which
>  		 * would require vdd on to handle it, and thus we
> diff --git a/drivers/gpu/drm/i915/display/intel_pps.c b/drivers/gpu/drm/i915/display/intel_pps.c
> index 9c986e8932f87..d3e6083ad5b79 100644
> --- a/drivers/gpu/drm/i915/display/intel_pps.c
> +++ b/drivers/gpu/drm/i915/display/intel_pps.c
> @@ -1075,13 +1075,13 @@ static void intel_pps_vdd_sanitize(struct intel_dp *intel_dp)
>  	edp_panel_vdd_schedule_off(intel_dp);
>  }
>  
> -bool intel_pps_have_power(struct intel_dp *intel_dp)
> +bool intel_pps_have_vdd_power(struct intel_dp *intel_dp)
>  {
>  	intel_wakeref_t wakeref;
>  	bool have_power = false;
>  
>  	with_intel_pps_lock(intel_dp, wakeref) {
> -		have_power = edp_have_panel_power(intel_dp) &&
> +		have_power = edp_have_panel_power(intel_dp) ||
>  						  edp_have_panel_vdd(intel_dp);
>  	}
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_pps.h b/drivers/gpu/drm/i915/display/intel_pps.h
> index fbb47f6f453e4..948523ce32417 100644
> --- a/drivers/gpu/drm/i915/display/intel_pps.h
> +++ b/drivers/gpu/drm/i915/display/intel_pps.h
> @@ -37,7 +37,7 @@ void intel_pps_vdd_on(struct intel_dp *intel_dp);
>  void intel_pps_on(struct intel_dp *intel_dp);
>  void intel_pps_off(struct intel_dp *intel_dp);
>  void intel_pps_vdd_off_sync(struct intel_dp *intel_dp);
> -bool intel_pps_have_power(struct intel_dp *intel_dp);
> +bool intel_pps_have_vdd_power(struct intel_dp *intel_dp);
>  void intel_pps_wait_power_cycle(struct intel_dp *intel_dp);
>  
>  void intel_pps_init(struct intel_dp *intel_dp);
> -- 
> 2.35.1

-- 
Ville Syrjälä
Intel