Re: [PATCH v5 07/13] drm/i915/icl: Program DSI clock and data lane timing params

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

On Tue, Jul 10, 2018 at 03:10:08PM +0530, Madhav Chauhan wrote:
> This patch programs D-PHY timing parameters for the
> clock and data lane (in escape clocks) of DSI
> controller (DSI port 0 and 1).
> These programmed timings would be used by DSI Controller
> to calculate link transition latencies of the data and
> clock lanes.
> 
> Signed-off-by: Madhav Chauhan <madhav.chauhan@intel.com>
> ---
>  drivers/gpu/drm/i915/icl_dsi.c       |  18 ++++
>  drivers/gpu/drm/i915/intel_dsi.h     |   3 +
>  drivers/gpu/drm/i915/intel_dsi_vbt.c | 200 +++++++++++++++++++++++++----------
>  3 files changed, 165 insertions(+), 56 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/icl_dsi.c b/drivers/gpu/drm/i915/icl_dsi.c
> index bc27e34..832772d 100644
> --- a/drivers/gpu/drm/i915/icl_dsi.c
> +++ b/drivers/gpu/drm/i915/icl_dsi.c
> @@ -284,6 +284,24 @@ static void gen11_dsi_setup_dphy_timings(struct intel_encoder *encoder)
>  		tmp |= intel_dsi->init_count;
>  		I915_WRITE(ICL_DSI_T_INIT_MASTER(port), tmp);
>  	}
> +
> +	/* Program DPHY clock lanes timings */
> +	for_each_dsi_port(port, intel_dsi->ports) {
> +		I915_WRITE(DPHY_CLK_TIMING_PARAM(port), intel_dsi->dphy_reg);
> +
> +		/* shadow register inside display core */
> +		I915_WRITE(DSI_CLK_TIMING_PARAM(port), intel_dsi->dphy_reg);
> +	}
> +
> +	/* Program DPHY data lanes timings */
> +	for_each_dsi_port(port, intel_dsi->ports) {
> +		I915_WRITE(DPHY_DATA_TIMING_PARAM(port),
> +			   intel_dsi->dphy_data_lane_reg);
> +
> +		/* shadow register inside display core */
> +		I915_WRITE(DSI_DATA_TIMING_PARAM(port),
> +			   intel_dsi->dphy_data_lane_reg);
> +	}
>  }
>  
>  static void gen11_dsi_enable_port_and_phy(struct intel_encoder *encoder)
> diff --git a/drivers/gpu/drm/i915/intel_dsi.h b/drivers/gpu/drm/i915/intel_dsi.h
> index ad7c1cb..9fd8526 100644
> --- a/drivers/gpu/drm/i915/intel_dsi.h
> +++ b/drivers/gpu/drm/i915/intel_dsi.h
> @@ -85,6 +85,9 @@ struct intel_dsi {
>  	u32 port_bits;
>  	u32 bw_timer;
>  	u32 dphy_reg;
> +
> +	/* data lanes dphy timing */
> +	u32 dphy_data_lane_reg;
>  	u32 video_frmt_cfg_bits;
>  	u16 lp_byte_clk;
>  
> diff --git a/drivers/gpu/drm/i915/intel_dsi_vbt.c b/drivers/gpu/drm/i915/intel_dsi_vbt.c
> index ac83d6b..428290d 100644
> --- a/drivers/gpu/drm/i915/intel_dsi_vbt.c
> +++ b/drivers/gpu/drm/i915/intel_dsi_vbt.c
> @@ -509,7 +509,9 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 panel_id)
>  	u32 bpp;
>  	u32 tlpx_ns, extra_byte_count, bitrate, tlpx_ui;
>  	u32 ui_num, ui_den;
> -	u32 prepare_cnt, exit_zero_cnt, clk_zero_cnt, trail_cnt;
> +	u32 prepare_cnt, exit_zero_cnt, clk_zero_cnt, trail_cnt, hs_zero_cnt;
> +	u32 tclk_pre_cnt, tclk_post_cnt;
> +	u32 tclk_pre_ns, tclk_post_ns;
>  	u32 ths_prepare_ns, tclk_trail_ns;
>  	u32 tclk_prepare_clkzero, ths_prepare_hszero;
>  	u32 lp_to_hs_switch, hs_to_lp_switch;
> @@ -624,76 +626,157 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 panel_id)
>  
>  	tclk_prepare_clkzero = mipi_config->tclk_prepare_clkzero;
>  	ths_prepare_hszero = mipi_config->ths_prepare_hszero;
> -
> +	tclk_trail_ns = max(mipi_config->tclk_trail, mipi_config->ths_trail);
> +	ths_prepare_ns = max(mipi_config->ths_prepare,
> +				mipi_config->tclk_prepare);
>  	/*
>  	 * B060
>  	 * LP byte clock = TLPX/ (8UI)
>  	 */
>  	intel_dsi->lp_byte_clk = DIV_ROUND_UP(tlpx_ns * ui_den, 8 * ui_num);
>  
> -	/* DDR clock period = 2 * UI
> -	 * UI(sec) = 1/(bitrate * 10^3) (bitrate is in KHZ)
> -	 * UI(nsec) = 10^6 / bitrate
> -	 * DDR clock period (nsec) = 2 * UI = (2 * 10^6)/ bitrate
> -	 * DDR clock count  = ns_value / DDR clock period
> -	 *
> +	/*
>  	 * For GEMINILAKE dphy_param_reg will be programmed in terms of
>  	 * HS byte clock count for other platform in HS ddr clock count
>  	 */
>  	mul = IS_GEMINILAKE(dev_priv) ? 8 : 2;
> -	ths_prepare_ns = max(mipi_config->ths_prepare,
> -			     mipi_config->tclk_prepare);
>  
> -	/* prepare count */
> -	prepare_cnt = DIV_ROUND_UP(ths_prepare_ns * ui_den, ui_num * mul);
> +	if (IS_ICELAKE(dev_priv)) {

I'd suggest extracting the icl vs. old things into separate functions.

> +		/*
> +		 * prepare cnt in escape clocks
> +		 * this field represents a hexadecimal value with a precision
> +		 * of 1.2 – i.e. the most significant bit is the integer
> +		 * and the least significant 2 bits are fraction bits.
> +		 * so, the field can represent a range of 0.25 to 1.75
> +		 */
> +		prepare_cnt = DIV_ROUND_UP(ths_prepare_ns * 4, tlpx_ns);
> +
> +		/* clk zero count in escape clocks */
> +		clk_zero_cnt = DIV_ROUND_UP(
> +					(tclk_prepare_clkzero - ths_prepare_ns),
> +					tlpx_ns);
> +
> +		/* trail cnt in escape clocks*/
> +		trail_cnt = DIV_ROUND_UP(tclk_trail_ns, tlpx_ns);
> +
> +		/* tclk pre/post count in escape clocks */
> +		tclk_post_ns = mipi_config->tclk_post;
> +		tclk_pre_ns = mipi_config->tclk_pre;
> +		tclk_pre_cnt = DIV_ROUND_UP(tclk_pre_ns, tlpx_ns);
> +		tclk_post_cnt = DIV_ROUND_UP(tclk_post_ns, tlpx_ns);
> +
> +		/* hs zero cnt in escape clocks */
> +		hs_zero_cnt = DIV_ROUND_UP(
> +					(ths_prepare_hszero - ths_prepare_ns),
> +					tlpx_ns);
> +
> +		/* hs exit zero cnt in escape clocks */
> +		exit_zero_cnt = DIV_ROUND_UP(mipi_config->ths_exit, tlpx_ns);
> +
> +		if (prepare_cnt > 0x7 ||
> +		    clk_zero_cnt > 0xF ||
> +		    tclk_pre_cnt > 0x3 ||
> +		    tclk_post_cnt > 0x7 ||
> +		    trail_cnt > 0x7 ||
> +		    hs_zero_cnt > 0xF ||
> +		    exit_zero_cnt > 0x7) {
> +			DRM_DEBUG_DRIVER("DPHY values crossing max limits,");
> +			DRM_DEBUG_DRIVER("restricting to max values\n");
> +		}

This doesn't match how we do it on the older platforms. Would be nice to
stick to a uniform apporoach across the board.

Maybe add some kind of small helper to make this stuff less repetitive:

void clamp_val(u32 *val, u32 limit, const char *name)
{
	if (*val <= limit)
		return;
	
	DEBUG("%s...\n", name, ...);
	*val = limit;
}

Could even mix in some cpp magic to stringify the name automagically.

> +
> +		prepare_cnt = (prepare_cnt > 0x7) ? 0x7 : prepare_cnt;
> +		clk_zero_cnt = (clk_zero_cnt > 0xF) ? 0xF : clk_zero_cnt;
> +		tclk_pre_cnt = (tclk_pre_cnt > 0x3) ? 0x3 : tclk_pre_cnt;
> +		tclk_post_cnt = (tclk_post_cnt > 0x7) ? 0x7 : tclk_post_cnt;
> +		trail_cnt = (trail_cnt > 0x7) ? 0x7 : trail_cnt;
> +		hs_zero_cnt = (hs_zero_cnt > 0xF) ? 0xF : hs_zero_cnt;
> +		exit_zero_cnt = (exit_zero_cnt > 0x7) ? 0x7 : exit_zero_cnt;
> +
> +		/* clock lane dphy timings */
> +		intel_dsi->dphy_reg |= (CLK_PREP_OVERRIDE |
> +					CLK_PREP_TIME(prepare_cnt) |
> +					CLK_ZERO_OVERRIDE |
> +					CLK_ZERO_TIME(clk_zero_cnt) |
> +					CLK_PRE_OVERRIDE |
> +					CLK_PRE_TIME(tclk_pre_cnt) |
> +					CLK_POST_OVERRIDE |
> +					CLK_POST_TIME(tclk_post_cnt) |
> +					CLK_TRAIL_OVERRIDE |
> +					CLK_TRAIL_TIME(trail_cnt));
> +
> +		/* data lanes dphy timings */
> +		intel_dsi->dphy_data_lane_reg = HS_PREP_OVERRIDE |
> +						HS_PREP_TIME(prepare_cnt) |
> +						HS_ZERO_OVERRIDE |
> +						HS_ZERO_TIME(hs_zero_cnt) |
> +						HS_TRAIL_OVERRIDE |
> +						HS_TRAIL_TIME(trail_cnt) |
> +						HS_EXIT_OVERRIDE |
> +						HS_EXIT_TIME(exit_zero_cnt);
> +	} else {
> +		/*
> +		 * DDR clock period = 2 * UI
> +		 * UI(sec) = 1/(bitrate * 10^3) (bitrate is in KHZ)
> +		 * UI(nsec) = 10^6 / bitrate
> +		 * DDR clock period (nsec) = 2 * UI = (2 * 10^6)/ bitrate
> +		 * DDR clock count  = ns_value / DDR clock period
> +		 */
>  
> -	if (prepare_cnt > PREPARE_CNT_MAX) {
> -		DRM_DEBUG_KMS("prepare count too high %u\n", prepare_cnt);
> -		prepare_cnt = PREPARE_CNT_MAX;
> -	}
> +		/* prepare count */
> +		prepare_cnt = DIV_ROUND_UP(ths_prepare_ns * ui_den,
> +							ui_num * mul);
>  
> -	/* exit zero count */
> -	exit_zero_cnt = DIV_ROUND_UP(
> +		if (prepare_cnt > PREPARE_CNT_MAX) {
> +			DRM_DEBUG_KMS("prepare count too high %u\n",
> +								prepare_cnt);
> +			prepare_cnt = PREPARE_CNT_MAX;
> +		}
> +
> +		/* exit zero count */
> +		exit_zero_cnt = DIV_ROUND_UP(
>  				(ths_prepare_hszero - ths_prepare_ns) * ui_den,
>  				ui_num * mul
>  				);
>  
> -	/*
> -	 * Exit zero is unified val ths_zero and ths_exit
> -	 * minimum value for ths_exit = 110ns
> -	 * min (exit_zero_cnt * 2) = 110/UI
> -	 * exit_zero_cnt = 55/UI
> -	 */
> -	if (exit_zero_cnt < (55 * ui_den / ui_num) && (55 * ui_den) % ui_num)
> -		exit_zero_cnt += 1;
> -
> -	if (exit_zero_cnt > EXIT_ZERO_CNT_MAX) {
> -		DRM_DEBUG_KMS("exit zero count too high %u\n", exit_zero_cnt);
> -		exit_zero_cnt = EXIT_ZERO_CNT_MAX;
> -	}
> +		/*
> +		 * Exit zero is unified val ths_zero and ths_exit
> +		 * minimum value for ths_exit = 110ns
> +		 * min (exit_zero_cnt * 2) = 110/UI
> +		 * exit_zero_cnt = 55/UI
> +		 */
> +		if (exit_zero_cnt < (55 * ui_den / ui_num) &&
> +					(55 * ui_den) % ui_num)
> +			exit_zero_cnt += 1;
> +
> +		if (exit_zero_cnt > EXIT_ZERO_CNT_MAX) {
> +			DRM_DEBUG_KMS("exit zero count too high %u\n",
> +								exit_zero_cnt);
> +			exit_zero_cnt = EXIT_ZERO_CNT_MAX;
> +		}
>  
> -	/* clk zero count */
> -	clk_zero_cnt = DIV_ROUND_UP(
> -				(tclk_prepare_clkzero -	ths_prepare_ns)
> -				* ui_den, ui_num * mul);
> +		/* clk zero count */
> +		clk_zero_cnt = DIV_ROUND_UP((tclk_prepare_clkzero -
> +						ths_prepare_ns)
> +						* ui_den, ui_num * mul);
>  
> -	if (clk_zero_cnt > CLK_ZERO_CNT_MAX) {
> -		DRM_DEBUG_KMS("clock zero count too high %u\n", clk_zero_cnt);
> -		clk_zero_cnt = CLK_ZERO_CNT_MAX;
> -	}
> +		if (clk_zero_cnt > CLK_ZERO_CNT_MAX) {
> +			DRM_DEBUG_KMS("clock zero count too high %u\n",
> +								clk_zero_cnt);
> +			clk_zero_cnt = CLK_ZERO_CNT_MAX;
> +		}
>  
> -	/* trail count */
> -	tclk_trail_ns = max(mipi_config->tclk_trail, mipi_config->ths_trail);
> -	trail_cnt = DIV_ROUND_UP(tclk_trail_ns * ui_den, ui_num * mul);
> +		/* trail cnt */
> +		trail_cnt = DIV_ROUND_UP(tclk_trail_ns * ui_den, ui_num * mul);
>  
> -	if (trail_cnt > TRAIL_CNT_MAX) {
> -		DRM_DEBUG_KMS("trail count too high %u\n", trail_cnt);
> -		trail_cnt = TRAIL_CNT_MAX;
> -	}
> +		if (trail_cnt > TRAIL_CNT_MAX) {
> +			DRM_DEBUG_KMS("trail count too high %u\n", trail_cnt);
> +			trail_cnt = TRAIL_CNT_MAX;
> +		}
>  
> -	/* B080 */
> -	intel_dsi->dphy_reg = exit_zero_cnt << 24 | trail_cnt << 16 |
> +		/* B080 */
> +		intel_dsi->dphy_reg = exit_zero_cnt << 24 | trail_cnt << 16 |
>  						clk_zero_cnt << 8 | prepare_cnt;
> +	}
>  
>  	/*
>  	 * LP to HS switch count = 4TLPX + PREP_COUNT * mul + EXIT_ZERO_COUNT *
> @@ -707,9 +790,10 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 panel_id)
>  	 */
>  	tlpx_ui = DIV_ROUND_UP(tlpx_ns * ui_den, ui_num);
>  
> -	/* B044 */
> -	/* FIXME:
> -	 * The comment above does not match with the code */
> +	/*
> +	 * B044
> +	 * FIXME: comment above does not match with the code
> +	 */

Unrelated changes.

>  	lp_to_hs_switch = DIV_ROUND_UP(4 * tlpx_ui + prepare_cnt * mul +
>  						exit_zero_cnt * mul + 10, 8);
>  
> @@ -718,8 +802,9 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 panel_id)
>  	intel_dsi->hs_to_lp_count = max(lp_to_hs_switch, hs_to_lp_switch);
>  	intel_dsi->hs_to_lp_count += extra_byte_count;
>  
> -	/* B088 */
> -	/* LP -> HS for clock lanes
> +	/*
> +	 * B088
> +	 * LP -> HS for clock lanes
>  	 * LP clk sync + LP11 + LP01 + tclk_prepare + tclk_zero +
>  	 *						extra byte count
>  	 * 2TPLX + 1TLPX + 1 TPLX(in ns) + prepare_cnt * 2 + clk_zero_cnt *
> @@ -735,7 +820,8 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 panel_id)
>  
>  	intel_dsi->clk_lp_to_hs_count += extra_byte_count;
>  
> -	/* HS->LP for Clock Lanes
> +	/*
> +	 * HS->LP for Clock Lanes
>  	 * Low Power clock synchronisations + 1Tx byteclk + tclk_trail +
>  	 *						Extra byte count
>  	 * 2TLPX + 8UI + (trail_count*2)(in UI) + Extra byte count
> @@ -782,9 +868,11 @@ bool intel_dsi_vbt_init(struct intel_dsi *intel_dsi, u16 panel_id)
>  	DRM_DEBUG_KMS("BTA %s\n",
>  			enableddisabled(!(intel_dsi->video_frmt_cfg_bits & DISABLE_VIDEO_BTA)));
>  
> -	/* delays in VBT are in unit of 100us, so need to convert
> +	/*
> +	 * delays in VBT are in unit of 100us, so need to convert
>  	 * here in ms
> -	 * Delay (100us) * 100 /1000 = Delay / 10 (ms) */
> +	 * Delay (100us) * 100 /1000 = Delay / 10 (ms)
> +	 */
>  	intel_dsi->backlight_off_delay = pps->bl_disable_delay / 10;
>  	intel_dsi->backlight_on_delay = pps->bl_enable_delay / 10;
>  	intel_dsi->panel_on_delay = pps->panel_on_delay / 10;
> -- 
> 2.7.4
> 
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-- 
Ville Syrjälä
Intel
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