[Intel-gfx] [PATCH] drm/i915/psr: Check for power state control capability.

[Nathan Ciobanu]

On Mon, Feb 26, 2018 at 07:27:23PM -0800, Dhinakaran Pandiyan wrote:
> eDP spec says - "If PSR/PSR2 is supported, the SET_POWER_CAPABLE bit in the
> EDP_GENERAL_CAPABILITY_1 register (DPCD Address 00701h, bit d7) must be set
> to 1."
> 
> Reject PSR on panels without this cap bit set as such panels cannot be
> controlled via SET_POWER & SET_DP_PWR_VOLTAGE register and the DP source
> needs to be able to do that for PSR.
> 
> Thanks to Nathan for debugging this.
> 
> Panel cap checks like this can be done just once, let's fix this
> when PSR dpcd init movement lands.
> 
> Cc: Nathan D Ciobanu <nathan.d.ciobanu at intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
 Tested-by: Nathan Ciobanu <nathan.d.ciobanu at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_psr.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
> index 89f41d28c44a..e0701b7f87f7 100644
> --- a/drivers/gpu/drm/i915/intel_psr.c
> +++ b/drivers/gpu/drm/i915/intel_psr.c
> @@ -405,6 +405,11 @@ void intel_psr_compute_config(struct intel_dp *intel_dp,
>  		return;
>  	}
>  
> +	if (!(intel_dp->edp_dpcd[1] & DP_EDP_SET_POWER_CAP)) {
> +		DRM_DEBUG_KMS("PSR condition failed: panel lacks power state control\n");
> +		return;
> +	}
> +
>  	/*
>  	 * FIXME psr2_support is messed up. It's both computed
>  	 * dynamically during PSR enable, and extracted from sink
> -- 
> 2.14.1
> 
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