Re: [PATCH v2 1/8] drm/rockchip/dsi: correct Feedback divider setting

Archit Taneja <architt@xxxxxxxxxxxxxx> · Fri, 13 Oct 2017 13:39:23 +0530

Hi,

On 09/26/2017 01:25 PM, Nickey Yang wrote:
This patch correct Feedback divider setting:
1、Set Feedback divider [8:5] when HIGH_PROGRAM_EN
2、Due to the use of a "by 2 pre-scaler," the range of the
feedback multiplication Feedback divider is limited to even
division numbers, and Feedback divider must be greater than
12, less than 1000.
3、Make the previously configured Feedback divider(LSB)
factors effective
4、Add the definition of the MIPI PHY register.

Slightly unrelated topic: We now have a generic dw-mipi-dsi bridge
driver. Can we consider moving to that instead of adding new features
within the rockchip kms driver?

Thanks,
Archit


Signed-off-by: Nickey Yang <nickey.yang@xxxxxxxxxxxxxx>
---
  drivers/gpu/drm/rockchip/dw-mipi-dsi.c | 219 ++++++++++++++++++++++-----------
  1 file changed, 146 insertions(+), 73 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
index 9a20b9d..c933a3a 100644
--- a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
+++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
@@ -228,7 +228,7 @@
  #define LOW_PROGRAM_EN		0
  #define HIGH_PROGRAM_EN		BIT(7)
  #define LOOP_DIV_LOW_SEL(val)	(((val) - 1) & 0x1f)
-#define LOOP_DIV_HIGH_SEL(val)	((((val) - 1) >> 5) & 0x1f)
+#define LOOP_DIV_HIGH_SEL(val)	((((val) - 1) >> 5) & 0xf)
  #define PLL_LOOP_DIV_EN		BIT(5)
  #define PLL_INPUT_DIV_EN	BIT(4)
  
@@ -254,6 +254,28 @@
  #define DW_MIPI_NEEDS_PHY_CFG_CLK	BIT(0)
  #define DW_MIPI_NEEDS_GRF_CLK		BIT(1)
  
+#define PLL_BIAS_CUR_SEL_CAP_VCO_CONTROL 0x10
+#define PLL_CP_CONTROL_PLL_LOCK_BYPASS 0x11
+#define PLL_LPF_AND_CP_CONTROL 0x12
+#define PLL_INPUT_DIVIDER_RATIO 0x17
+#define PLL_LOOP_DIVIDER_RATIO 0x18
+#define PLL_INPUT_AND_LOOP_DIVIDER_RATIOS_CONTROL 0x19
+#define BANDGAP_AND_BIAS_CONTROL 0x20
+#define TERMINATION_RESISTER_CONTROL 0x21
+#define AFE_BIAS_BANDGAP_ANALOG_PROGRAMMABILITY 0x22
+#define HS_RX_CONTROL_OF_LANE_0 0x44
+#define HS_TX_CLOCK_LANE_REQUEST_STATE_TIME_CONTROL 0x60
+#define HS_TX_CLOCK_LANE_PREPARE_STATE_TIME_CONTROL 0x61
+#define HS_TX_CLOCK_LANE_HS_ZERO_STATE_TIME_CONTROL 0x62
+#define HS_TX_CLOCK_LANE_TRAIL_STATE_TIME_CONTROL 0x63
+#define HS_TX_CLOCK_LANE_EXIT_STATE_TIME_CONTROL 0x64
+#define HS_TX_CLOCK_LANE_POST_TIME_CONTROL 0x65
+#define HS_TX_DATA_LANE_REQUEST_STATE_TIME_CONTROL 0x70
+#define HS_TX_DATA_LANE_PREPARE_STATE_TIME_CONTROL 0x71
+#define HS_TX_DATA_LANE_HS_ZERO_STATE_TIME_CONTROL 0x72
+#define HS_TX_DATA_LANE_TRAIL_STATE_TIME_CONTROL 0x73
+#define HS_TX_DATA_LANE_EXIT_STATE_TIME_CONTROL 0x74
+
  enum {
  	BANDGAP_97_07,
  	BANDGAP_98_05,
@@ -447,53 +469,79 @@ static int dw_mipi_dsi_phy_init(struct dw_mipi_dsi *dsi)
  		return ret;
  	}
  
-	dw_mipi_dsi_phy_write(dsi, 0x10, BYPASS_VCO_RANGE |
-					 VCO_RANGE_CON_SEL(vco) |
-					 VCO_IN_CAP_CON_LOW |
-					 REF_BIAS_CUR_SEL);
-
-	dw_mipi_dsi_phy_write(dsi, 0x11, CP_CURRENT_3MA);
-	dw_mipi_dsi_phy_write(dsi, 0x12, CP_PROGRAM_EN | LPF_PROGRAM_EN |
-					 LPF_RESISTORS_20_KOHM);
-
-	dw_mipi_dsi_phy_write(dsi, 0x44, HSFREQRANGE_SEL(testdin));
-
-	dw_mipi_dsi_phy_write(dsi, 0x17, INPUT_DIVIDER(dsi->input_div));
-	dw_mipi_dsi_phy_write(dsi, 0x18, LOOP_DIV_LOW_SEL(dsi->feedback_div) |
-					 LOW_PROGRAM_EN);
-	dw_mipi_dsi_phy_write(dsi, 0x18, LOOP_DIV_HIGH_SEL(dsi->feedback_div) |
-					 HIGH_PROGRAM_EN);
-	dw_mipi_dsi_phy_write(dsi, 0x19, PLL_LOOP_DIV_EN | PLL_INPUT_DIV_EN);
-
-	dw_mipi_dsi_phy_write(dsi, 0x22, LOW_PROGRAM_EN |
-					 BIASEXTR_SEL(BIASEXTR_127_7));
-	dw_mipi_dsi_phy_write(dsi, 0x22, HIGH_PROGRAM_EN |
-					 BANDGAP_SEL(BANDGAP_96_10));
-
-	dw_mipi_dsi_phy_write(dsi, 0x20, POWER_CONTROL | INTERNAL_REG_CURRENT |
-					 BIAS_BLOCK_ON | BANDGAP_ON);
-
-	dw_mipi_dsi_phy_write(dsi, 0x21, TER_RESISTOR_LOW | TER_CAL_DONE |
-					 SETRD_MAX | TER_RESISTORS_ON);
-	dw_mipi_dsi_phy_write(dsi, 0x21, TER_RESISTOR_HIGH | LEVEL_SHIFTERS_ON |
-					 SETRD_MAX | POWER_MANAGE |
-					 TER_RESISTORS_ON);
-
-	dw_mipi_dsi_phy_write(dsi, 0x60, TLP_PROGRAM_EN | ns2bc(dsi, 500));
-	dw_mipi_dsi_phy_write(dsi, 0x61, THS_PRE_PROGRAM_EN | ns2ui(dsi, 40));
-	dw_mipi_dsi_phy_write(dsi, 0x62, THS_ZERO_PROGRAM_EN | ns2bc(dsi, 300));
-	dw_mipi_dsi_phy_write(dsi, 0x63, THS_PRE_PROGRAM_EN | ns2ui(dsi, 100));
-	dw_mipi_dsi_phy_write(dsi, 0x64, BIT(5) | ns2bc(dsi, 100));
-	dw_mipi_dsi_phy_write(dsi, 0x65, BIT(5) | (ns2bc(dsi, 60) + 7));
-
-	dw_mipi_dsi_phy_write(dsi, 0x70, TLP_PROGRAM_EN | ns2bc(dsi, 500));
-	dw_mipi_dsi_phy_write(dsi, 0x71,
+	dw_mipi_dsi_phy_write(dsi, PLL_BIAS_CUR_SEL_CAP_VCO_CONTROL,
+			      BYPASS_VCO_RANGE |
+			      VCO_RANGE_CON_SEL(vco) |
+			      VCO_IN_CAP_CON_LOW |
+			      REF_BIAS_CUR_SEL);
+
+	dw_mipi_dsi_phy_write(dsi, PLL_CP_CONTROL_PLL_LOCK_BYPASS,
+			      CP_CURRENT_3MA);
+	dw_mipi_dsi_phy_write(dsi, PLL_LPF_AND_CP_CONTROL,
+			      CP_PROGRAM_EN | LPF_PROGRAM_EN |
+			      LPF_RESISTORS_20_KOHM);
+
+	dw_mipi_dsi_phy_write(dsi, HS_RX_CONTROL_OF_LANE_0,
+			      HSFREQRANGE_SEL(testdin));
+
+	dw_mipi_dsi_phy_write(dsi, PLL_INPUT_DIVIDER_RATIO,
+			      INPUT_DIVIDER(dsi->input_div));
+	dw_mipi_dsi_phy_write(dsi, PLL_LOOP_DIVIDER_RATIO,
+			      LOOP_DIV_LOW_SEL(dsi->feedback_div) |
+			      LOW_PROGRAM_EN);
+	/*
+	 * we need set 0x19 immediately to make the configrued LSB
+	 * effective according to IP simulation and lab test results.
+	 * Only in this way can we get correct mipi phy pll frequency.
+	 */
+	dw_mipi_dsi_phy_write(dsi, PLL_INPUT_AND_LOOP_DIVIDER_RATIOS_CONTROL,
+			      PLL_LOOP_DIV_EN | PLL_INPUT_DIV_EN);
+	dw_mipi_dsi_phy_write(dsi, PLL_LOOP_DIVIDER_RATIO,
+			      LOOP_DIV_HIGH_SEL(dsi->feedback_div) |
+			      HIGH_PROGRAM_EN);
+	dw_mipi_dsi_phy_write(dsi, PLL_INPUT_AND_LOOP_DIVIDER_RATIOS_CONTROL,
+			      PLL_LOOP_DIV_EN | PLL_INPUT_DIV_EN);
+
+	dw_mipi_dsi_phy_write(dsi, AFE_BIAS_BANDGAP_ANALOG_PROGRAMMABILITY,
+			      LOW_PROGRAM_EN | BIASEXTR_SEL(BIASEXTR_127_7));
+	dw_mipi_dsi_phy_write(dsi, AFE_BIAS_BANDGAP_ANALOG_PROGRAMMABILITY,
+			      HIGH_PROGRAM_EN | BANDGAP_SEL(BANDGAP_96_10));
+
+	dw_mipi_dsi_phy_write(dsi, BANDGAP_AND_BIAS_CONTROL,
+			      POWER_CONTROL | INTERNAL_REG_CURRENT |
+			      BIAS_BLOCK_ON | BANDGAP_ON);
+
+	dw_mipi_dsi_phy_write(dsi, TERMINATION_RESISTER_CONTROL,
+			      TER_RESISTOR_LOW | TER_CAL_DONE |
+			      SETRD_MAX | TER_RESISTORS_ON);
+	dw_mipi_dsi_phy_write(dsi, TERMINATION_RESISTER_CONTROL,
+			      TER_RESISTOR_HIGH | LEVEL_SHIFTERS_ON |
+			      SETRD_MAX | POWER_MANAGE |
+			      TER_RESISTORS_ON);
+
+	dw_mipi_dsi_phy_write(dsi, HS_TX_CLOCK_LANE_REQUEST_STATE_TIME_CONTROL,
+			      TLP_PROGRAM_EN | ns2bc(dsi, 500));
+	dw_mipi_dsi_phy_write(dsi, HS_TX_CLOCK_LANE_PREPARE_STATE_TIME_CONTROL,
+			      THS_PRE_PROGRAM_EN | ns2ui(dsi, 40));
+	dw_mipi_dsi_phy_write(dsi, HS_TX_CLOCK_LANE_HS_ZERO_STATE_TIME_CONTROL,
+			      THS_ZERO_PROGRAM_EN | ns2bc(dsi, 300));
+	dw_mipi_dsi_phy_write(dsi, HS_TX_CLOCK_LANE_TRAIL_STATE_TIME_CONTROL,
+			      THS_PRE_PROGRAM_EN | ns2ui(dsi, 100));
+	dw_mipi_dsi_phy_write(dsi, HS_TX_CLOCK_LANE_EXIT_STATE_TIME_CONTROL,
+			      BIT(5) | ns2bc(dsi, 100));
+	dw_mipi_dsi_phy_write(dsi, HS_TX_CLOCK_LANE_POST_TIME_CONTROL,
+			      BIT(5) | (ns2bc(dsi, 60) + 7));
+
+	dw_mipi_dsi_phy_write(dsi, HS_TX_DATA_LANE_REQUEST_STATE_TIME_CONTROL,
+			      TLP_PROGRAM_EN | ns2bc(dsi, 500));
+	dw_mipi_dsi_phy_write(dsi, HS_TX_DATA_LANE_PREPARE_STATE_TIME_CONTROL,
  			      THS_PRE_PROGRAM_EN | (ns2ui(dsi, 50) + 5));
-	dw_mipi_dsi_phy_write(dsi, 0x72,
+	dw_mipi_dsi_phy_write(dsi, HS_TX_DATA_LANE_HS_ZERO_STATE_TIME_CONTROL,
  			      THS_ZERO_PROGRAM_EN | (ns2bc(dsi, 140) + 2));
-	dw_mipi_dsi_phy_write(dsi, 0x73,
+	dw_mipi_dsi_phy_write(dsi, HS_TX_DATA_LANE_TRAIL_STATE_TIME_CONTROL,
  			      THS_PRE_PROGRAM_EN | (ns2ui(dsi, 60) + 8));
-	dw_mipi_dsi_phy_write(dsi, 0x74, BIT(5) | ns2bc(dsi, 100));
+	dw_mipi_dsi_phy_write(dsi, HS_TX_DATA_LANE_EXIT_STATE_TIME_CONTROL,
+			      BIT(5) | ns2bc(dsi, 100));
  
  	dsi_write(dsi, DSI_PHY_RSTZ, PHY_ENFORCEPLL | PHY_ENABLECLK |
  				     PHY_UNRSTZ | PHY_UNSHUTDOWNZ);
@@ -521,11 +569,16 @@ static int dw_mipi_dsi_phy_init(struct dw_mipi_dsi *dsi)
  static int dw_mipi_dsi_get_lane_bps(struct dw_mipi_dsi *dsi,
  				    struct drm_display_mode *mode)
  {
-	unsigned int i, pre;
-	unsigned long mpclk, pllref, tmp;
-	unsigned int m = 1, n = 1, target_mbps = 1000;
+	unsigned long mpclk, tmp;
+	unsigned int target_mbps = 1000;
  	unsigned int max_mbps = dptdin_map[ARRAY_SIZE(dptdin_map) - 1].max_mbps;
  	int bpp;
+	unsigned long best_freq = 0;
+	unsigned long fvco_min, fvco_max, fin, fout;
+	unsigned int min_prediv, max_prediv;
+	unsigned int _prediv, uninitialized_var(best_prediv);
+	unsigned long _fbdiv, uninitialized_var(best_fbdiv);
+	unsigned long min_delta = ULONG_MAX;
  
  	bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
  	if (bpp < 0) {
@@ -544,34 +597,54 @@ static int dw_mipi_dsi_get_lane_bps(struct dw_mipi_dsi *dsi,
  			dev_err(dsi->dev, "DPHY clock frequency is out of range\n");
  	}
  
-	pllref = DIV_ROUND_UP(clk_get_rate(dsi->pllref_clk), USEC_PER_SEC);
-	tmp = pllref;
-
-	/*
-	 * The limits on the PLL divisor are:
-	 *
-	 *	5MHz <= (pllref / n) <= 40MHz
-	 *
-	 * we walk over these values in descreasing order so that if we hit
-	 * an exact match for target_mbps it is more likely that "m" will be
-	 * even.
-	 *
-	 * TODO: ensure that "m" is even after this loop.
-	 */
-	for (i = pllref / 5; i > (pllref / 40); i--) {
-		pre = pllref / i;
-		if ((tmp > (target_mbps % pre)) && (target_mbps / pre < 512)) {
-			tmp = target_mbps % pre;
-			n = i;
-			m = target_mbps / pre;
+	fin = clk_get_rate(dsi->pllref_clk);
+	fout = target_mbps * USEC_PER_SEC;
+
+	/* constraint: 5Mhz <= Fref / N <= 40MHz */
+	min_prediv = DIV_ROUND_UP(fin, 40 * USEC_PER_SEC);
+	max_prediv = fin / (5 * USEC_PER_SEC);
+
+	/* constraint: 80MHz <= Fvco <= 1500Mhz */
+	fvco_min = 80 * USEC_PER_SEC;
+	fvco_max = 1500 * USEC_PER_SEC;
+
+	for (_prediv = min_prediv; _prediv <= max_prediv; _prediv++) {
+		u64 tmp;
+		u32 delta;
+		/* Fvco = Fref * M / N */
+		tmp = (u64)fout * _prediv;
+		do_div(tmp, fin);
+		_fbdiv = tmp;
+		/*
+		 * Due to the use of a "by 2 pre-scaler," the range of the
+		 * feedback multiplication value M is limited to even division
+		 * numbers, and m must be greater than 12, less than 1000.
+		 */
+		if (_fbdiv <= 12 || _fbdiv >= 1000)
+			continue;
+
+		_fbdiv += _fbdiv % 2;
+
+		tmp = (u64)_fbdiv * fin;
+		do_div(tmp, _prediv);
+		if (tmp < fvco_min || tmp > fvco_max)
+			continue;
+
+		delta = abs(fout - tmp);
+		if (delta < min_delta) {
+			best_prediv = _prediv;
+			best_fbdiv = _fbdiv;
+			min_delta = delta;
+			best_freq = tmp;
  		}
-		if (tmp == 0)
-			break;
  	}
  
-	dsi->lane_mbps = pllref / n * m;
-	dsi->input_div = n;
-	dsi->feedback_div = m;
+	if (best_freq) {
+		dsi->lane_mbps = DIV_ROUND_UP(best_freq, USEC_PER_SEC);
+		dsi->input_div = best_prediv;
+		dsi->feedback_div = best_fbdiv;
+	} else
+		dev_err(dsi->dev, "Can not find best_freq for DPHY\n");
  
  	return 0;
  }


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