From 6dc60a6e6af08c9c52a84eff5c3dfc7f742a5de4 Mon Sep 17 00:00:00 2001
From: Antonio Borneo <antonio.borneo@foss.st.com>
Date: Tue, 13 Jul 2021 16:49:41 +0200
Subject: drm/stm: dsi: compute the transition time from LP to HS and back
Git-commit: 5cc4e71f0199391b0e311c44e79736c13eea269d
Patch-mainline: v5.15-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
The driver uses a conservative set of hardcoded values for the
maximum time delay of the transitions between LP and HS, either
for data and clock lanes.
By using the info in STM32MP157 datasheet, valid also for other ST
devices, compute the actual delay from the lane's bps.
Signed-off-by: Antonio Borneo <antonio.borneo@foss.st.com>
Reviewed-by: Philippe Cornu <philippe.cornu@foss.st.com>
Acked-by: Philippe Cornu <philippe.cornu@foss.st.com>
Signed-off-by: Philippe Cornu <philippe.cornu@foss.st.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210713144941.3599-1-antonio.borneo@foss.st.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/stm/dw_mipi_dsi-stm.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c b/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
index 8399d337589d..32cb41b2202f 100644
--- a/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
+++ b/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
@@ -309,14 +309,23 @@ dw_mipi_dsi_get_lane_mbps(void *priv_data, const struct drm_display_mode *mode,
return 0;
}
+#define DSI_PHY_DELAY(fp, vp, mbps) DIV_ROUND_UP((fp) * (mbps) + 1000 * (vp), 8000)
+
static int
dw_mipi_dsi_phy_get_timing(void *priv_data, unsigned int lane_mbps,
struct dw_mipi_dsi_dphy_timing *timing)
{
- timing->clk_hs2lp = 0x40;
- timing->clk_lp2hs = 0x40;
- timing->data_hs2lp = 0x40;
- timing->data_lp2hs = 0x40;
+ /*
+ * From STM32MP157 datasheet, valid for STM32F469, STM32F7x9, STM32H747
+ * phy_clkhs2lp_time = (272+136*UI)/(8*UI)
+ * phy_clklp2hs_time = (512+40*UI)/(8*UI)
+ * phy_hs2lp_time = (192+64*UI)/(8*UI)
+ * phy_lp2hs_time = (256+32*UI)/(8*UI)
+ */
+ timing->clk_hs2lp = DSI_PHY_DELAY(272, 136, lane_mbps);
+ timing->clk_lp2hs = DSI_PHY_DELAY(512, 40, lane_mbps);
+ timing->data_hs2lp = DSI_PHY_DELAY(192, 64, lane_mbps);
+ timing->data_lp2hs = DSI_PHY_DELAY(256, 32, lane_mbps);
return 0;
}
--
2.38.1