Re: [PATCH 07/11] drm/i915/dp: Exit PSR before do a aux channel transaction

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Fri, Mar 30, 2018 at 03:23:32PM -0700, José Roberto de Souza wrote:
> When PSR/PSR2 is enabled hardware can do aux ch transactions by it
> self.
> Spec requires that PSR is inactive before do any aux ch transaction
> in HSW and BDW, for skl+ there is a aux ch mutex but the use is not
> recommended.
> So exiting PSR/PSR2 and waiting the transition to inactive to prevent
> any concurrent access between hardware and software in aux ch
> registers.
> 
> VLV and CHV hardware don't do any aux as software is responsible to
> do all the buffer tracking and it sends the wake up aux ch message
> to sink.
>

ahh cool... I get back what I said on some previous patch.
I like where it is going, but...

> BSpec: 7530, 799 and 7532
> 
> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c  | 38 ++++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_drv.h |  2 ++
>  drivers/gpu/drm/i915/intel_psr.c |  8 ++++++++
>  3 files changed, 48 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 62f82c4298ac..fedee4e7ed24 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -1062,6 +1062,41 @@ static uint32_t skl_get_aux_send_ctl(struct intel_dp *intel_dp,
>  	       DP_AUX_CH_CTL_SYNC_PULSE_SKL(32);
>  }
>  
> +/**
> + * intel_dp_aux_ch_get - Get total control of aux ch registers
> + *
> + * By exiting or disabling any hardware feature that can also use the aux ch
> + * registers at the same time as driver, this function will give total control
> + * of aux ch registers to driver.
> + */
> +static void intel_dp_aux_ch_get(struct intel_dp *intel_dp)
> +{
> +	if (!intel_dp->exit_psr_on_aux_ch_xfer)
> +		return;
> +
> +	intel_psr_activate_block_get(intel_dp);
> +	intel_psr_exit(intel_dp, true);

decision on exit and activate should be inside the block_get and block_put,
based on current state of the counters.

> +}
> +
> +/**
> + * intel_dp_aux_ch_put - Release aux ch registers control
> + *
> + * It is the intel_dp_aux_ch_get() counterpart.
> + */
> +static void intel_dp_aux_ch_put(struct intel_dp *intel_dp)
> +{
> +	if (!intel_dp->exit_psr_on_aux_ch_xfer)
> +		return;
> +
> +	intel_psr_activate_block_put(intel_dp);
> +	/* Usually more than just one aux ch transaction is executed when
> +	 * handling some event, activating PSR right way would cause several
> +	 * msecs of delay waiting PSR to exit for each aux ch transaction, so
> +	 * here asking it to be scheduled.
> +	 */
> +	intel_psr_activate(intel_dp, true);
> +}
> +
>  static int
>  intel_dp_aux_xfer(struct intel_dp *intel_dp,
>  		  const uint8_t *send, int send_bytes,
> @@ -1101,6 +1136,8 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
>  
>  	intel_dp_check_edp(intel_dp);
>  
> +	intel_dp_aux_ch_get(intel_dp);
> +
>  	/* Try to wait for any previous AUX channel activity */
>  	for (try = 0; try < 3; try++) {
>  		status = I915_READ_NOTRACE(ch_ctl);
> @@ -1223,6 +1260,7 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
>  
>  	ret = recv_bytes;
>  out:
> +	intel_dp_aux_ch_put(intel_dp);
>  	pm_qos_update_request(&dev_priv->pm_qos, PM_QOS_DEFAULT_VALUE);
>  
>  	if (vdd)
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 020b96324135..177478f0b032 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1139,6 +1139,8 @@ struct intel_dp {
>  
>  	/* Displayport compliance testing */
>  	struct intel_dp_compliance compliance;
> +
> +	bool exit_psr_on_aux_ch_xfer;
>  };
>  
>  struct intel_lspcon {
> diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
> index 8702dbafb42d..f88f12246a23 100644
> --- a/drivers/gpu/drm/i915/intel_psr.c
> +++ b/drivers/gpu/drm/i915/intel_psr.c
> @@ -665,6 +665,13 @@ void intel_psr_enable(struct intel_dp *intel_dp,
>  				      msecs_to_jiffies(intel_dp->panel_power_cycle_delay * 5));
>  	}
>  
> +	/* From all platforms that supports PSR/PSR2 this 2 is the ones that
> +	 * don't have restrictions about use of the aux ch while PSR/PSR2 is
> +	 * enabled.
> +	 */
> +	if (!(IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)))
> +		intel_dp->exit_psr_on_aux_ch_xfer = true;
> +
>  unlock:
>  	mutex_unlock(&dev_priv->psr.lock);
>  }
> @@ -732,6 +739,7 @@ void intel_psr_disable(struct intel_dp *intel_dp,
>  
>  	dev_priv->psr.disable_source(intel_dp);
>  
> +	intel_dp->exit_psr_on_aux_ch_xfer = false;
>  	/* Disable PSR on Sink */
>  	drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG, 0);
>  
> -- 
> 2.16.3
> 
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