drm/bridge/synopsys: dsi: driver-specific configuration of phy timings

The timing values for dw-dsi are often dependent on the used display and
according to Philippe Cornu will most likely also depend on the used phy
technology in the soc-specific implementation.

To solve this and allow specific implementations to define them as needed
add a new get_timing callback to phy_ops and call this from the dphy_timing
function to retrieve the necessary values for the specific mode.

Right now this handles the hs2lp + lp2hs where Rockchip SoCs need handling
according to the phy speed, while STM seems to be ok with static values.

changes in v5:
- rebase on 5.5-rc1
- merge into px30 dsi series to prevent ordering conflicts

changes in v4:
- rebase to make it directly fit on top of drm-misc-next after all

changes in v3:
- check existence of phy_ops->get_timing in __dw_mipi_dsi_probe()
- emit actual error when get_timing() call fails
- add tags from Philippe and Yannick

changes in v2:
- add driver-specific handling, don't force all bridge users to use
  the same timings, as suggested by Philippe

Suggested-by: Philippe Cornu <philippe.cornu@st.com>
Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Reviewed-by: Philippe Cornu <philippe.cornu@st.com>
Tested-by: Yannick Fertre <yannick.fertre@st.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191209143130.4553-2-heiko@sntech.de

2 files changed, 79 insertions, 0 deletions

diff --git a/drivers/gpu/drm/rockchip/Kconfig b/drivers/gpu/drm/rockchip/Kconfig
index 1670a5cae3c7..310aa1546893 100644
--- a/drivers/gpu/drm/rockchip/Kconfig
+++ b/drivers/gpu/drm/rockchip/Kconfig
@@ -46,6 +46,7 @@ config ROCKCHIP_DW_HDMI
 
 config ROCKCHIP_DW_MIPI_DSI
 	bool "Rockchip specific extensions for Synopsys DW MIPI DSI"
+	select GENERIC_PHY_MIPI_DPHY
 	help
 	  This selects support for Rockchip SoC specific extensions
 	  for the Synopsys DesignWare HDMI driver. If you want to
diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
index 5f23cf702cb4..b41d86ee9e17 100644
--- a/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi-rockchip.c
@@ -559,9 +559,87 @@ dw_mipi_dsi_get_lane_mbps(void *priv_data, const struct drm_display_mode *mode,
 	return 0;
 }
 
+struct hstt {
+	unsigned int maxfreq;
+	struct dw_mipi_dsi_dphy_timing timing;
+};
+
+#define HSTT(_maxfreq, _c_lp2hs, _c_hs2lp, _d_lp2hs, _d_hs2lp)	\
+{					\
+	.maxfreq = _maxfreq,		\
+	.timing = {			\
+		.clk_lp2hs = _c_lp2hs,	\
+		.clk_hs2lp = _c_hs2lp,	\
+		.data_lp2hs = _d_lp2hs,	\
+		.data_hs2lp = _d_hs2lp,	\
+	}				\
+}
+
+/* Table A-3 High-Speed Transition Times */
+struct hstt hstt_table[] = {
+	HSTT(  90,  32, 20,  26, 13),
+	HSTT( 100,  35, 23,  28, 14),
+	HSTT( 110,  32, 22,  26, 13),
+	HSTT( 130,  31, 20,  27, 13),
+	HSTT( 140,  33, 22,  26, 14),
+	HSTT( 150,  33, 21,  26, 14),
+	HSTT( 170,  32, 20,  27, 13),
+	HSTT( 180,  36, 23,  30, 15),
+	HSTT( 200,  40, 22,  33, 15),
+	HSTT( 220,  40, 22,  33, 15),
+	HSTT( 240,  44, 24,  36, 16),
+	HSTT( 250,  48, 24,  38, 17),
+	HSTT( 270,  48, 24,  38, 17),
+	HSTT( 300,  50, 27,  41, 18),
+	HSTT( 330,  56, 28,  45, 18),
+	HSTT( 360,  59, 28,  48, 19),
+	HSTT( 400,  61, 30,  50, 20),
+	HSTT( 450,  67, 31,  55, 21),
+	HSTT( 500,  73, 31,  59, 22),
+	HSTT( 550,  79, 36,  63, 24),
+	HSTT( 600,  83, 37,  68, 25),
+	HSTT( 650,  90, 38,  73, 27),
+	HSTT( 700,  95, 40,  77, 28),
+	HSTT( 750, 102, 40,  84, 28),
+	HSTT( 800, 106, 42,  87, 30),
+	HSTT( 850, 113, 44,  93, 31),
+	HSTT( 900, 118, 47,  98, 32),
+	HSTT( 950, 124, 47, 102, 34),
+	HSTT(1000, 130, 49, 107, 35),
+	HSTT(1050, 135, 51, 111, 37),
+	HSTT(1100, 139, 51, 114, 38),
+	HSTT(1150, 146, 54, 120, 40),
+	HSTT(1200, 153, 57, 125, 41),
+	HSTT(1250, 158, 58, 130, 42),
+	HSTT(1300, 163, 58, 135, 44),
+	HSTT(1350, 168, 60, 140, 45),
+	HSTT(1400, 172, 64, 144, 47),
+	HSTT(1450, 176, 65, 148, 48),
+	HSTT(1500, 181, 66, 153, 50)
+};
+
+static int
+dw_mipi_dsi_phy_get_timing(void *priv_data, unsigned int lane_mbps,
+			   struct dw_mipi_dsi_dphy_timing *timing)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(hstt_table); i++)
+		if (lane_mbps < hstt_table[i].maxfreq)
+			break;
+
+	if (i == ARRAY_SIZE(hstt_table))
+		i--;
+
+	*timing = hstt_table[i].timing;
+
+	return 0;
+}
+
 static const struct dw_mipi_dsi_phy_ops dw_mipi_dsi_rockchip_phy_ops = {
 	.init = dw_mipi_dsi_phy_init,
 	.get_lane_mbps = dw_mipi_dsi_get_lane_mbps,
+	.get_timing = dw_mipi_dsi_phy_get_timing,
 };
 
 static void dw_mipi_dsi_rockchip_config(struct dw_mipi_dsi_rockchip *dsi,