From: Michael Trimarchi michael@amarulasolutions.com
Upstream linux commit 9a8406ba1a9a29.
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.
Tested-by: Liu Ying victor.liu@nxp.com # RM67191 DSI panel on i.MX8mq EVK Reviewed-by: Andrzej Hajda andrzej.hajda@intel.com Reviewed-by: Neil Armstrong narmstrong@baylibre.com # for phy-meson-axg-mipi-dphy.c Tested-by: Neil Armstrong narmstrong@baylibre.com # for phy-meson-axg-mipi-dphy.c Tested-by: Guido Günther agx@sigxcpu.org # Librem 5 (imx8mq) with it's rather picky panel Reviewed-by: Laurent Pinchart laurent.pinchart@ideasonboard.com Signed-off-by: Liu Ying victor.liu@nxp.com Link: https://lore.kernel.org/r/20220124024007.1465018-1-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/meson-axg-mipi-dphy.c | 2 +- drivers/phy/phy-core-mipi-dphy.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/phy/meson-axg-mipi-dphy.c b/drivers/phy/meson-axg-mipi-dphy.c index 3f89de19970b..fb10ccca6ac1 100644 --- a/drivers/phy/meson-axg-mipi-dphy.c +++ b/drivers/phy/meson-axg-mipi-dphy.c @@ -237,7 +237,7 @@ static int phy_meson_axg_mipi_dphy_power_on(struct phy *phy) (DIV_ROUND_UP(priv->config.clk_zero, temp) << 16) | (DIV_ROUND_UP(priv->config.clk_prepare, temp) << 24)); regmap_write(priv->regmap, MIPI_DSI_CLK_TIM1, - DIV_ROUND_UP(priv->config.clk_pre, temp)); + DIV_ROUND_UP(priv->config.clk_pre, BITS_PER_BYTE));
regmap_write(priv->regmap, MIPI_DSI_HS_TIM, DIV_ROUND_UP(priv->config.hs_exit, temp) | diff --git a/drivers/phy/phy-core-mipi-dphy.c b/drivers/phy/phy-core-mipi-dphy.c index 79cab9125002..27cff85709d9 100644 --- a/drivers/phy/phy-core-mipi-dphy.c +++ b/drivers/phy/phy-core-mipi-dphy.c @@ -36,7 +36,7 @@ static int phy_mipi_dphy_calc_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;