From 9a8406ba1a9a2965c27e0db1d7753471d12ee9ff Mon Sep 17 00:00:00 2001 From: Liu Ying Date: Mon, 24 Jan 2022 10:40:07 +0800 Subject: phy: dphy: Correct clk_pre parameter MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The D-PHY specification (v1.2) explicitly mentions that the T-CLK-PRE parameter's unit is Unit Interval(UI) and the minimum value is 8. Also, kernel doc of the 'clk_pre' member of struct phy_configure_opts_mipi_dphy mentions that it should be in UI. However, the dphy core driver wrongly sets 'clk_pre' to 8000, which seems to hint that it's in picoseconds. So, let's fix the dphy core driver to correctly reflect the T-CLK-PRE parameter's minimum value according to the D-PHY specification. I'm assuming that all impacted custom drivers shall program values in TxByteClkHS cycles into hardware for the T-CLK-PRE parameter. The D-PHY specification mentions that the frequency of TxByteClkHS is exactly 1/8 the High-Speed(HS) bit rate(each HS bit consumes one UI). So, relevant custom driver code is changed to program those values as DIV_ROUND_UP(cfg->clk_pre, BITS_PER_BYTE), then. 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: 2ed869990e14 ("phy: Add MIPI D-PHY configuration options") Tested-by: Liu Ying # RM67191 DSI panel on i.MX8mq EVK Reviewed-by: Andrzej Hajda Reviewed-by: Neil Armstrong # for phy-meson-axg-mipi-dphy.c Tested-by: Neil Armstrong # for phy-meson-axg-mipi-dphy.c Tested-by: Guido Günther # Librem 5 (imx8mq) with it's rather picky panel Reviewed-by: Laurent Pinchart Signed-off-by: Liu Ying Link: https://lore.kernel.org/r/20220124024007.1465018-1-victor.liu@nxp.com Signed-off-by: Vinod Koul --- drivers/phy/phy-core-mipi-dphy.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/phy/phy-core-mipi-dphy.c') diff --git a/drivers/phy/phy-core-mipi-dphy.c b/drivers/phy/phy-core-mipi-dphy.c index 288c9c67aa74..ccb4045685cd 100644 --- a/drivers/phy/phy-core-mipi-dphy.c +++ b/drivers/phy/phy-core-mipi-dphy.c @@ -36,7 +36,7 @@ int phy_mipi_dphy_get_default_config(unsigned long pixel_clock, cfg->clk_miss = 0; cfg->clk_post = 60000 + 52 * ui; - cfg->clk_pre = 8000; + cfg->clk_pre = 8; cfg->clk_prepare = 38000; cfg->clk_settle = 95000; cfg->clk_term_en = 0; @@ -97,7 +97,7 @@ int phy_mipi_dphy_config_validate(struct phy_configure_opts_mipi_dphy *cfg) if (cfg->clk_post < (60000 + 52 * ui)) return -EINVAL; - if (cfg->clk_pre < 8000) + if (cfg->clk_pre < 8) return -EINVAL; if (cfg->clk_prepare < 38000 || cfg->clk_prepare > 95000) -- cgit v1.2.3