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authorLiu Ying <victor.liu@nxp.com>2022-02-16 10:12:57 +0300
committerVinod Koul <vkoul@kernel.org>2022-02-25 11:44:06 +0300
commit3153fa38e38af566cf6454a03b1dbadaf6f323c0 (patch)
tree92fe0fa1f7720a97bed49fda7e273c0152c9925c /drivers/phy
parentae532b2b7aa5a3dad036aef4e0b177607172d276 (diff)
downloadlinux-3153fa38e38af566cf6454a03b1dbadaf6f323c0.tar.xz
phy: dphy: Correct lpx parameter and its derivatives(ta_{get,go,sure})
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@intel.com> Cc: Neil Armstrong <narmstrong@baylibre.com> Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com> Cc: Kishon Vijay Abraham I <kishon@ti.com> Cc: Vinod Koul <vkoul@kernel.org> Cc: Heiko Stuebner <heiko@sntech.de> Cc: Maxime Ripard <mripard@kernel.org> Cc: Guido Günther <agx@sigxcpu.org> 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>
Diffstat (limited to 'drivers/phy')
-rw-r--r--drivers/phy/phy-core-mipi-dphy.c4
1 files 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;