From: Michael Trimarchi michael@amarulasolutions.com
Upstream linux commit 3153fa38e38af5.
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.
Signed-off-by: Liu Ying victor.liu@nxp.com Link: https://lore.kernel.org/r/20220216071257.1647703-1-victor.liu@nxp.com Signed-off-by: Vinod Koul vkoul@kernel.org Signed-off-by: Michael Trimarchi michael@amarulasolutions.com Signed-off-by: Dario Binacchi dario.binacchi@amarulasolutions.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 727c2b040520..79cab9125002 100644 --- a/drivers/phy/phy-core-mipi-dphy.c +++ b/drivers/phy/phy-core-mipi-dphy.c @@ -64,10 +64,10 @@ static int phy_mipi_dphy_calc_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;