[PATCH v2 0/3] DSI Controller improvements for Rockchip platforms

[PATCH v2 0/3] DSI Controller improvements for Rockchip platforms

[Chaoyi Chen]

From: Chaoyi Chen <chaoyi.chen@rock-chips.com>

This series is dedicated to enhancing the DSI controller and PHY timing
interaction, refining the lane rate calculation, and addressing the
associated hardware limitations.

Changes in v2:
- Link to v1: https://lore.kernel.org/all/20260324085838.90-1-kernel@airkyi.com/
- Fix the unit conversion for max_mbps.
- Split the lane rate calculation into a separate patch.
- Add more comment about timing config.

Chaoyi Chen (3):
  drm/rockchip: dsi: Add maximum per lane bit rate calculation
  drm/rockchip: dsi: Add dphy_get_timing support for multiple PHY types
  drm/rockchip: dsi: Relax the lane rate margin requirements

 .../gpu/drm/rockchip/dw-mipi-dsi-rockchip.c   | 66 +++++++++++++++++--
 1 file changed, 60 insertions(+), 6 deletions(-)

-- 
2.53.0

[PATCH v2 1/3] drm/rockchip: dsi: Add maximum per lane bit rate calculation

[Chaoyi Chen]

From: Chaoyi Chen <chaoyi.chen@rock-chips.com>

Different chips have varying support for the maximum bit rate per lane.

Add calculation for the maximum per lane bit rate for various chip
platforms.

Signed-off-by: Chaoyi Chen <chaoyi.chen@rock-chips.com>
---
Changes in v2:
- Fix the unit conversion for max_mbps.
- Split the lane rate calculation into a separate patch.

---
 drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
index 3547d91b25d3..1060abec9f29 100644
--- a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
@@ -268,6 +268,7 @@ struct rockchip_dw_dsi_chip_data {
 
 	unsigned int flags;
 	unsigned int max_data_lanes;
+	unsigned long max_bit_rate_per_lane;
 };
 
 struct dw_mipi_dsi_rockchip {
@@ -565,7 +566,7 @@ dw_mipi_dsi_get_lane_mbps(void *priv_data, const struct drm_display_mode *mode,
 	int bpp;
 	unsigned long mpclk, tmp;
 	unsigned int target_mbps = 1000;
-	unsigned int max_mbps = dppa_map[ARRAY_SIZE(dppa_map) - 1].max_mbps;
+	unsigned int max_mbps;
 	unsigned long best_freq = 0;
 	unsigned long fvco_min, fvco_max, fin, fout;
 	unsigned int min_prediv, max_prediv;
@@ -573,6 +574,7 @@ dw_mipi_dsi_get_lane_mbps(void *priv_data, const struct drm_display_mode *mode,
 	unsigned long _fbdiv, best_fbdiv;
 	unsigned long min_delta = ULONG_MAX;
 
+	max_mbps = dsi->cdata->max_bit_rate_per_lane / USEC_PER_SEC;
 	dsi->format = format;
 	bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
 	if (bpp < 0) {
@@ -1503,6 +1505,7 @@ static const struct rockchip_dw_dsi_chip_data px30_chip_data[] = {
 						PX30_DSI_FORCETXSTOPMODE), 0),
 
 		.max_data_lanes = 4,
+		.max_bit_rate_per_lane = 1000000000UL,
 	},
 	{ /* sentinel */ }
 };
@@ -1515,6 +1518,7 @@ static const struct rockchip_dw_dsi_chip_data rk3128_chip_data[] = {
 						RK3128_DSI_FORCERXMODE |
 						RK3128_DSI_FORCETXSTOPMODE), 0),
 		.max_data_lanes = 4,
+		.max_bit_rate_per_lane = 1000000000UL,
 	},
 	{ /* sentinel */ }
 };
@@ -1527,6 +1531,7 @@ static const struct rockchip_dw_dsi_chip_data rk3288_chip_data[] = {
 		.lcdsel_lit = FIELD_PREP_WM16_CONST(RK3288_DSI0_LCDC_SEL, 1),
 
 		.max_data_lanes = 4,
+		.max_bit_rate_per_lane = 1500000000UL,
 	},
 	{
 		.reg = 0xff964000,
@@ -1535,6 +1540,7 @@ static const struct rockchip_dw_dsi_chip_data rk3288_chip_data[] = {
 		.lcdsel_lit = FIELD_PREP_WM16_CONST(RK3288_DSI1_LCDC_SEL, 1),
 
 		.max_data_lanes = 4,
+		.max_bit_rate_per_lane = 1500000000UL,
 	},
 	{ /* sentinel */ }
 };
@@ -1547,6 +1553,7 @@ static const struct rockchip_dw_dsi_chip_data rk3368_chip_data[] = {
 						RK3368_DSI_FORCETXSTOPMODE |
 						RK3368_DSI_FORCERXMODE), 0),
 		.max_data_lanes = 4,
+		.max_bit_rate_per_lane = 1500000000UL,
 	},
 	{ /* sentinel */ }
 };
@@ -1634,6 +1641,7 @@ static const struct rockchip_dw_dsi_chip_data rk3399_chip_data[] = {
 
 		.flags = DW_MIPI_NEEDS_PHY_CFG_CLK | DW_MIPI_NEEDS_GRF_CLK,
 		.max_data_lanes = 4,
+		.max_bit_rate_per_lane = 1500000000UL,
 	},
 	{
 		.reg = 0xff968000,
@@ -1658,6 +1666,7 @@ static const struct rockchip_dw_dsi_chip_data rk3399_chip_data[] = {
 
 		.flags = DW_MIPI_NEEDS_PHY_CFG_CLK | DW_MIPI_NEEDS_GRF_CLK,
 		.max_data_lanes = 4,
+		.max_bit_rate_per_lane = 1500000000UL,
 
 		.dphy_rx_init = rk3399_dphy_tx1rx1_init,
 		.dphy_rx_power_on = rk3399_dphy_tx1rx1_power_on,
@@ -1674,6 +1683,7 @@ static const struct rockchip_dw_dsi_chip_data rk3506_chip_data[] = {
 			     FIELD_PREP_WM16_CONST(RK3506_DSI_FORCERXMODE, 0) |
 			     FIELD_PREP_WM16_CONST(RK3506_DSI_FORCETXSTOPMODE, 0)),
 		.max_data_lanes = 2,
+		.max_bit_rate_per_lane = 1500000000UL,
 	},
 	{ /* sentinel */ }
 };
@@ -1687,6 +1697,7 @@ static const struct rockchip_dw_dsi_chip_data rk3568_chip_data[] = {
 			     FIELD_PREP_WM16_CONST(RK3568_DSI0_TURNDISABLE, 0) |
 			     FIELD_PREP_WM16_CONST(RK3568_DSI0_FORCERXMODE, 0)),
 		.max_data_lanes = 4,
+		.max_bit_rate_per_lane = 1200000000UL,
 	},
 	{
 		.reg = 0xfe070000,
@@ -1696,6 +1707,7 @@ static const struct rockchip_dw_dsi_chip_data rk3568_chip_data[] = {
 			     FIELD_PREP_WM16_CONST(RK3568_DSI1_TURNDISABLE, 0) |
 			     FIELD_PREP_WM16_CONST(RK3568_DSI1_FORCERXMODE, 0)),
 		.max_data_lanes = 4,
+		.max_bit_rate_per_lane = 1200000000UL,
 	},
 	{ /* sentinel */ }
 };
@@ -1708,6 +1720,7 @@ static const struct rockchip_dw_dsi_chip_data rv1126_chip_data[] = {
 			     FIELD_PREP_WM16_CONST(RV1126_DSI_FORCERXMODE, 0) |
 			     FIELD_PREP_WM16_CONST(RV1126_DSI_FORCETXSTOPMODE, 0)),
 		.max_data_lanes = 4,
+		.max_bit_rate_per_lane = 1000000000UL,
 	},
 	{ /* sentinel */ }
 };
-- 
2.53.0

[PATCH v2 2/3] drm/rockchip: dsi: Add dphy_get_timing support for multiple PHY types

[Chaoyi Chen]

From: Chaoyi Chen <chaoyi.chen@rock-chips.com>

Currently, there are generally two types of DPHY for Rockchip. One is
the DPHY used by RK3288/RK3399, whose timing is described by Table A-3
High-Speed Transition Times in the databook. The other is the DPHY used
by PX30 and its successors. If its timing is still described using
RK3288/RK3399, it may not perform correctly on some DSI panel.

Add dphy_get_timing for different D-PHY types to adapt to timing
differences. The configuration details are as follows:

- RK3288/RK3399: Select the corresponding entry from the timing table based
                 on the data rate.
- PX30 and later platforms: Use a fixed timing configuration.

Signed-off-by: Chaoyi Chen <chaoyi.chen@rock-chips.com>
---
Changes in v2:
- Add more comment about timing config.

---
 .../gpu/drm/rockchip/dw-mipi-dsi-rockchip.c   | 45 ++++++++++++++++++-
 1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
index 1060abec9f29..e64dfc327891 100644
--- a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
@@ -247,6 +247,7 @@ enum {
 	BIASEXTR_127_7,
 };
 
+struct dw_mipi_dsi_rockchip;
 struct rockchip_dw_dsi_chip_data {
 	u32 reg;
 
@@ -262,6 +263,9 @@ struct rockchip_dw_dsi_chip_data {
 	u32 lanecfg2_grf_reg;
 	u32 lanecfg2;
 
+	int (*dphy_get_timing)(struct dw_mipi_dsi_rockchip *dsi, unsigned int lane_mbps,
+			       struct dw_mipi_dsi_dphy_timing *timing);
+
 	int (*dphy_rx_init)(struct phy *phy);
 	int (*dphy_rx_power_on)(struct phy *phy);
 	int (*dphy_rx_power_off)(struct phy *phy);
@@ -721,8 +725,9 @@ static struct hstt hstt_table[] = {
 };
 
 static int
-dw_mipi_dsi_phy_get_timing(void *priv_data, unsigned int lane_mbps,
-			   struct dw_mipi_dsi_dphy_timing *timing)
+dw_mipi_dsi_phy_rk3288_get_timing(struct dw_mipi_dsi_rockchip *dsi,
+				  unsigned int lane_mbps,
+				  struct dw_mipi_dsi_dphy_timing *timing)
 {
 	int i;
 
@@ -738,6 +743,32 @@ dw_mipi_dsi_phy_get_timing(void *priv_data, unsigned int lane_mbps,
 	return 0;
 }
 
+static const struct dw_mipi_dsi_dphy_timing dphy_timing_px30 = {
+	.clk_lp2hs = 0x40,
+	.clk_hs2lp = 0x40,
+	.data_lp2hs = 0x10,
+	.data_hs2lp = 0x14,
+};
+
+static int
+dw_mipi_dsi_phy_px30_get_timing(struct dw_mipi_dsi_rockchip *dsi,
+				unsigned int lane_mbps,
+				struct dw_mipi_dsi_dphy_timing *timing)
+{
+	*timing = dphy_timing_px30;
+
+	return 0;
+}
+
+static int
+dw_mipi_dsi_phy_get_timing(void *priv_data, unsigned int lane_mbps,
+			   struct dw_mipi_dsi_dphy_timing *timing)
+{
+	struct dw_mipi_dsi_rockchip *dsi = priv_data;
+
+	return dsi->cdata->dphy_get_timing(dsi, lane_mbps, timing);
+}
+
 static const struct dw_mipi_dsi_phy_ops dw_mipi_dsi_rockchip_phy_ops = {
 	.init = dw_mipi_dsi_phy_init,
 	.power_on = dw_mipi_dsi_phy_power_on,
@@ -1506,6 +1537,7 @@ static const struct rockchip_dw_dsi_chip_data px30_chip_data[] = {
 
 		.max_data_lanes = 4,
 		.max_bit_rate_per_lane = 1000000000UL,
+		.dphy_get_timing = dw_mipi_dsi_phy_px30_get_timing,
 	},
 	{ /* sentinel */ }
 };
@@ -1519,6 +1551,7 @@ static const struct rockchip_dw_dsi_chip_data rk3128_chip_data[] = {
 						RK3128_DSI_FORCETXSTOPMODE), 0),
 		.max_data_lanes = 4,
 		.max_bit_rate_per_lane = 1000000000UL,
+		.dphy_get_timing = dw_mipi_dsi_phy_px30_get_timing,
 	},
 	{ /* sentinel */ }
 };
@@ -1532,6 +1565,7 @@ static const struct rockchip_dw_dsi_chip_data rk3288_chip_data[] = {
 
 		.max_data_lanes = 4,
 		.max_bit_rate_per_lane = 1500000000UL,
+		.dphy_get_timing = dw_mipi_dsi_phy_rk3288_get_timing,
 	},
 	{
 		.reg = 0xff964000,
@@ -1541,6 +1575,7 @@ static const struct rockchip_dw_dsi_chip_data rk3288_chip_data[] = {
 
 		.max_data_lanes = 4,
 		.max_bit_rate_per_lane = 1500000000UL,
+		.dphy_get_timing = dw_mipi_dsi_phy_rk3288_get_timing,
 	},
 	{ /* sentinel */ }
 };
@@ -1554,6 +1589,7 @@ static const struct rockchip_dw_dsi_chip_data rk3368_chip_data[] = {
 						RK3368_DSI_FORCERXMODE), 0),
 		.max_data_lanes = 4,
 		.max_bit_rate_per_lane = 1500000000UL,
+		.dphy_get_timing = dw_mipi_dsi_phy_px30_get_timing,
 	},
 	{ /* sentinel */ }
 };
@@ -1642,6 +1678,7 @@ static const struct rockchip_dw_dsi_chip_data rk3399_chip_data[] = {
 		.flags = DW_MIPI_NEEDS_PHY_CFG_CLK | DW_MIPI_NEEDS_GRF_CLK,
 		.max_data_lanes = 4,
 		.max_bit_rate_per_lane = 1500000000UL,
+		.dphy_get_timing = dw_mipi_dsi_phy_rk3288_get_timing,
 	},
 	{
 		.reg = 0xff968000,
@@ -1671,6 +1708,7 @@ static const struct rockchip_dw_dsi_chip_data rk3399_chip_data[] = {
 		.dphy_rx_init = rk3399_dphy_tx1rx1_init,
 		.dphy_rx_power_on = rk3399_dphy_tx1rx1_power_on,
 		.dphy_rx_power_off = rk3399_dphy_tx1rx1_power_off,
+		.dphy_get_timing = dw_mipi_dsi_phy_rk3288_get_timing,
 	},
 	{ /* sentinel */ }
 };
@@ -1698,6 +1736,7 @@ static const struct rockchip_dw_dsi_chip_data rk3568_chip_data[] = {
 			     FIELD_PREP_WM16_CONST(RK3568_DSI0_FORCERXMODE, 0)),
 		.max_data_lanes = 4,
 		.max_bit_rate_per_lane = 1200000000UL,
+		.dphy_get_timing = dw_mipi_dsi_phy_px30_get_timing,
 	},
 	{
 		.reg = 0xfe070000,
@@ -1708,6 +1747,7 @@ static const struct rockchip_dw_dsi_chip_data rk3568_chip_data[] = {
 			     FIELD_PREP_WM16_CONST(RK3568_DSI1_FORCERXMODE, 0)),
 		.max_data_lanes = 4,
 		.max_bit_rate_per_lane = 1200000000UL,
+		.dphy_get_timing = dw_mipi_dsi_phy_px30_get_timing,
 	},
 	{ /* sentinel */ }
 };
@@ -1721,6 +1761,7 @@ static const struct rockchip_dw_dsi_chip_data rv1126_chip_data[] = {
 			     FIELD_PREP_WM16_CONST(RV1126_DSI_FORCETXSTOPMODE, 0)),
 		.max_data_lanes = 4,
 		.max_bit_rate_per_lane = 1000000000UL,
+		.dphy_get_timing = dw_mipi_dsi_phy_px30_get_timing,
 	},
 	{ /* sentinel */ }
 };
-- 
2.53.0

[PATCH v2 3/3] drm/rockchip: dsi: Relax the lane rate margin requirements

[Chaoyi Chen]

From: Chaoyi Chen <chaoyi.chen@rock-chips.com>

The lane rate is calculated as follows:

	Lane_Rate = Pixel_Clk * BPP / lanes * Overhead

The overhead factor is set to 1/0.8, equivalent to a 25% overhead.

Now let's consider the case of RGB888 (BPP24) with a pclk of 148.5MHz.
The lane rate equals 148.5M * 24 / 4 * 1.25 = 1113.75 Mbps.

However, this is beyond the capability of certain platforms limited to a
1Gbps lane rate. On the other hand, we have observed that some DSI panel
actually perform worse with higher overhead.

So we are considering relaxing the bandwidth margin requirements.
According to the downstream test results, adopting 1/0.9 seems to
be a sound approach, corresponding to an overhead of about 11%.

Signed-off-by: Chaoyi Chen <chaoyi.chen@rock-chips.com>
---
 drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
index e64dfc327891..8af9d6934d27 100644
--- a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
@@ -590,8 +590,8 @@ dw_mipi_dsi_get_lane_mbps(void *priv_data, const struct drm_display_mode *mode,
 
 	mpclk = DIV_ROUND_UP(mode->clock, MSEC_PER_SEC);
 	if (mpclk) {
-		/* take 1 / 0.8, since mbps must big than bandwidth of RGB */
-		tmp = mpclk * (bpp / lanes) * 10 / 8;
+		/* take 1 / 0.9, since mbps must big than bandwidth of RGB */
+		tmp = mpclk * (bpp / lanes) * 10 / 9;
 		if (tmp < max_mbps)
 			target_mbps = tmp;
 		else
@@ -601,7 +601,7 @@ dw_mipi_dsi_get_lane_mbps(void *priv_data, const struct drm_display_mode *mode,
 
 	/* for external phy only a the mipi_dphy_config is necessary */
 	if (dsi->phy) {
-		phy_mipi_dphy_get_default_config(mode->clock * 1000 * 10 / 8,
+		phy_mipi_dphy_get_default_config(mode->clock * 1000 * 10 / 9,
 						 bpp, lanes,
 						 &dsi->phy_opts.mipi_dphy);
 		dsi->lane_mbps = target_mbps;
-- 
2.53.0