[PATCH] phy: dphy: Correct lpx parameter and its derivatives(ta_{get, go, sure})

[Liu Ying]

According to the comment of the function phy_mipi_dphy_get_default_config(),
it uses minimum D-PHY timings based on MIPI D-PHY specification.  They are
derived from the valid ranges specified in Section 6.9, Table 14, Page 41
of the D-PHY specification (v1.2).  The table 14 explicitly mentions that
the minimum T-LPX parameter is 50 nanoseconds and the minimum TA-SURE
parameter is T-LPX nanoseconds.  Likewise, the kernel doc of the 'lpx' and
'ta_sure' members of struct phy_configure_opts_mipi_dphy mentions that
the minimum values are 50000 picoseconds and @lpx picoseconds respectively.
Also, the function phy_mipi_dphy_config_validate() checks if cfg->lpx is
less than 50000 picoseconds and if cfg->ta_sure is less than cfg->lpx,
which hints the same minimum values.

Without this patch, the function phy_mipi_dphy_get_default_config()
wrongly sets cfg->lpx to 60000 picoseconds and cfg->ta_sure to 2 * cfg->lpx.
So, let's correct them to 50000 picoseconds and cfg->lpx respectively.

Note that I've only tested the patch with RM67191 DSI panel on i.MX8mq EVK.
Help is needed to test with other i.MX8mq, Meson and Rockchip platforms,
as I don't have the hardwares.

Fixes: dddc97e82303 ("phy: dphy: Add configuration helpers")
Cc: Andrzej Hajda <andrzej.hajda at intel.com>
Cc: Neil Armstrong <narmstrong at baylibre.com>
Cc: Laurent Pinchart <Laurent.pinchart at ideasonboard.com>
Cc: Kishon Vijay Abraham I <kishon at ti.com>
Cc: Vinod Koul <vkoul at kernel.org>
Cc: Heiko Stuebner <heiko at sntech.de>
Cc: Maxime Ripard <mripard at kernel.org>
Cc: Guido Günther <agx at sigxcpu.org>
Signed-off-by: Liu Ying <victor.liu at nxp.com>
---
 drivers/phy/phy-core-mipi-dphy.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/phy/phy-core-mipi-dphy.c b/drivers/phy/phy-core-mipi-dphy.c
index ccb4045685cd..929e86d6558e 100644
--- a/drivers/phy/phy-core-mipi-dphy.c
+++ b/drivers/phy/phy-core-mipi-dphy.c
@@ -64,10 +64,10 @@ int phy_mipi_dphy_get_default_config(unsigned long pixel_clock,
 	cfg->hs_trail = max(4 * 8 * ui, 60000 + 4 * 4 * ui);
 
 	cfg->init = 100;
-	cfg->lpx = 60000;
+	cfg->lpx = 50000;
 	cfg->ta_get = 5 * cfg->lpx;
 	cfg->ta_go = 4 * cfg->lpx;
-	cfg->ta_sure = 2 * cfg->lpx;
+	cfg->ta_sure = cfg->lpx;
 	cfg->wakeup = 1000;
 
 	cfg->hs_clk_rate = hs_clk_rate;
-- 
2.25.1