[Intel-gfx] [PATCH 4/6] drm/i915/xelpd: Handle PSR2 SDP indication in the prior scanline

[Gwan-gyeong Mun]

looks good to me.
Reviewed-by: Gwan-gyeong Mun <gwan-gyeong.mun at intel.com>

On 6/16/21 11:31 PM, José Roberto de Souza wrote:
> In some modes there is not enough time during hblank to transmit PSR2
> SDP plus the pixels CRC SDP, if such case happens PSR2 needs to be
> disabled.
> But eDP spec 1.4b allows to transmit PSR2 SDP in a prior scanline
> alone and than later the CRC SDP, allowing PSR2 to be enabled in
> those hblank constrained modes.
> 
> BSpec: 49274
> Cc: Gwan-gyeong Mun <gwan-gyeong.mun at intel.com>
> Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
> ---
>   .../drm/i915/display/intel_display_types.h    |  2 +
>   drivers/gpu/drm/i915/display/intel_psr.c      | 37 +++++++++++++++++++
>   drivers/gpu/drm/i915/i915_reg.h               |  1 +
>   3 files changed, 40 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index f89152ca52a20..56c4cb45c99df 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1040,6 +1040,7 @@ struct intel_crtc_state {
>   	bool has_psr;
>   	bool has_psr2;
>   	bool enable_psr2_sel_fetch;
> +	bool req_psr2_sdp_prior_scanline;
>   	u32 dc3co_exitline;
>   	u16 su_y_granularity;
>   
> @@ -1494,6 +1495,7 @@ struct intel_psr {
>   	bool colorimetry_support;
>   	bool psr2_enabled;
>   	bool psr2_sel_fetch_enabled;
> +	bool req_psr2_sdp_prior_scanline;
>   	u8 sink_sync_latency;
>   	ktime_t last_entry_attempt;
>   	ktime_t last_exit;
> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
> index e508816911fad..3cb8758be4042 100644
> --- a/drivers/gpu/drm/i915/display/intel_psr.c
> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
> @@ -418,6 +418,9 @@ static void intel_psr_enable_sink(struct intel_dp *intel_dp)
>   			dpcd_val |= DP_PSR_CRC_VERIFICATION;
>   	}
>   
> +	if (intel_dp->psr.req_psr2_sdp_prior_scanline)
> +		dpcd_val |= DP_PSR_SU_REGION_SCANLINE_CAPTURE;
> +
>   	drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG, dpcd_val);
>   
>   	drm_dp_dpcd_writeb(&intel_dp->aux, DP_SET_POWER, DP_SET_POWER_D0);
> @@ -585,6 +588,9 @@ static void hsw_activate_psr2(struct intel_dp *intel_dp)
>   		val |= EDP_PSR2_FAST_WAKE(7);
>   	}
>   
> +	if (intel_dp->psr.req_psr2_sdp_prior_scanline)
> +		val |= EDP_PSR2_SU_SDP_SCANLINE;
> +
>   	if (intel_dp->psr.psr2_sel_fetch_enabled) {
>   		/* WA 1408330847 */
>   		if (IS_TGL_DISPLAY_STEP(dev_priv, STEP_A0, STEP_A0) ||
> @@ -814,6 +820,29 @@ static bool psr2_granularity_check(struct intel_dp *intel_dp,
>   	return true;
>   }
>   
> +static bool _compute_psr2_sdp_prior_scanline_indication(struct intel_dp *intel_dp,
> +							struct intel_crtc_state *crtc_state)
> +{
> +	const struct drm_display_mode *adjusted_mode = &crtc_state->uapi.adjusted_mode;
> +	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> +	u32 hblank_total, hblank_ns, req_ns;
> +
> +	hblank_total = adjusted_mode->crtc_hblank_end - adjusted_mode->crtc_hblank_start;
> +	hblank_ns = div_u64(1000000ULL * hblank_total, adjusted_mode->crtc_clock);
> +
> +	/* From spec: (72 / number of lanes) * 1000 / symbol clock frequency MHz */
> +	req_ns = (72 / crtc_state->lane_count) * 1000 / (crtc_state->port_clock / 1000);
> +
> +	if ((hblank_ns - req_ns) > 100)
> +		return true;
> +
> +	if (DISPLAY_VER(dev_priv) < 13 || intel_dp->edp_dpcd[0] < DP_EDP_14b)
> +		return false;
> +
> +	crtc_state->req_psr2_sdp_prior_scanline = true;
> +	return true;
> +}
> +
>   static bool intel_psr2_config_valid(struct intel_dp *intel_dp,
>   				    struct intel_crtc_state *crtc_state)
>   {
> @@ -926,6 +955,12 @@ static bool intel_psr2_config_valid(struct intel_dp *intel_dp,
>   		return false;
>   	}
>   
> +	if (!_compute_psr2_sdp_prior_scanline_indication(intel_dp, crtc_state)) {
> +		drm_dbg_kms(&dev_priv->drm,
> +			    "PSR2 not enabled, PSR2 SDP indication do not fit in hblank\n");
> +		return false;
> +	}
> +
>   	tgl_dc3co_exitline_compute_config(intel_dp, crtc_state);
>   	return true;
>   }
> @@ -1173,6 +1208,8 @@ static void intel_psr_enable_locked(struct intel_dp *intel_dp,
>   	intel_dp->psr.dc3co_exit_delay = val;
>   	intel_dp->psr.dc3co_exitline = crtc_state->dc3co_exitline;
>   	intel_dp->psr.psr2_sel_fetch_enabled = crtc_state->enable_psr2_sel_fetch;
> +	intel_dp->psr.req_psr2_sdp_prior_scanline =
> +		crtc_state->req_psr2_sdp_prior_scanline;
>   
>   	if (!psr_interrupt_error_check(intel_dp))
>   		return;
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 568e5f108e2c4..e0bd60fe7a190 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -4590,6 +4590,7 @@ enum {
>   #define   TGL_EDP_PSR2_BLOCK_COUNT_NUM_2	(0 << 28)
>   #define   TGL_EDP_PSR2_BLOCK_COUNT_NUM_3	(1 << 28)
>   #define   EDP_Y_COORDINATE_ENABLE		REG_BIT(25) /* display 10, 11 and 12 */
> +#define   EDP_PSR2_SU_SDP_SCANLINE		REG_BIT(25) /* display 13+ */
>   #define   EDP_MAX_SU_DISABLE_TIME(t)		((t) << 20)
>   #define   EDP_MAX_SU_DISABLE_TIME_MASK		(0x1f << 20)
>   #define   EDP_PSR2_IO_BUFFER_WAKE_MAX_LINES	8
>