Re: [PATCH 5/7] drm/i915/psr: Order DP aux transactions correctly

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Daniel Vetter <daniel.vetter@intel.com>,
	Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
	"Pandiyan, Dhinakaran" <dhinakaran.pandiyan@intel.com>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>
Subject: Re: [PATCH 5/7] drm/i915/psr: Order DP aux transactions correctly
Date: Wed, 18 May 2016 20:51:19 +0300	[thread overview]
Message-ID: <20160518175119.GA4329@intel.com> (raw)
In-Reply-To: <1463590036-17824-5-git-send-email-daniel.vetter@ffwll.ch>

On Wed, May 18, 2016 at 06:47:14PM +0200, Daniel Vetter wrote:
> On bdw/hsw we have a separate psr dp aux registers to set up, but on
> bdw it's shared with the main dp aux thing. Which means any subsequent
> dp aux transaction will trample over it, and hence must be done
> beforehand.
> 
> Also this means we can't do any dp aux transactions while PSR is
> active, or at least we must restore the old state.
> 
> Probably need a psr disable/enable pair around dp aux transactions in
> general.

Yep. Looks like there's a note even in the HSW spec to forbid AUX while
in PSR, even though it has the separate regs.

"SRD AUX channel transactions must not be sent while DDI A AUX is being
 used. SRD must be completely disabled before a DDI A AUX channel
 transaction can be sent."

> 
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Cc: Sonika Jindal <sonika.jindal@intel.com>
> Cc: Durgadoss R <durgadoss.r@intel.com>
> Cc: "Pandiyan, Dhinakaran" <dhinakaran.pandiyan@intel.com>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/intel_psr.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
> index a088be65a267..87805078c8a3 100644
> --- a/drivers/gpu/drm/i915/intel_psr.c
> +++ b/drivers/gpu/drm/i915/intel_psr.c
> @@ -197,6 +197,13 @@ static void hsw_psr_enable_sink(struct intel_dp *intel_dp)
>  				DP_SINK_DEVICE_AUX_FRAME_SYNC_CONF,
>  				DP_AUX_FRAME_SYNC_ENABLE);
>  
> +	if (dev_priv->psr.link_standby)
> +		drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG,
> +				   DP_PSR_ENABLE | DP_PSR_MAIN_LINK_ACTIVE);
> +	else
> +		drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG,
> +				   DP_PSR_ENABLE);
> +
>  	aux_ctl_reg = psr_aux_ctl_reg(dev_priv, port);
>  
>  	/* Setup AUX registers */
> @@ -224,13 +231,6 @@ static void hsw_psr_enable_sink(struct intel_dp *intel_dp)
>  		   (precharge << DP_AUX_CH_CTL_PRECHARGE_2US_SHIFT) |
>  		   (aux_clock_divider << DP_AUX_CH_CTL_BIT_CLOCK_2X_SHIFT));
>  	}
> -
> -	if (dev_priv->psr.link_standby)
> -		drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG,
> -				   DP_PSR_ENABLE | DP_PSR_MAIN_LINK_ACTIVE);
> -	else
> -		drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG,
> -				   DP_PSR_ENABLE);
>  }
>  
>  static void vlv_psr_enable_source(struct intel_dp *intel_dp)
> -- 
> 2.8.1
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Ville Syrjälä
Intel OTC
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