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| author | Liu Ying <victor.liu@nxp.com> | 2022-01-24 10:40:07 +0800 |
|---|---|---|
| committer | Vinod Koul <vkoul@kernel.org> | 2022-02-02 10:33:04 +0530 |
| commit | 9a8406ba1a9a2965c27e0db1d7753471d12ee9ff (patch) | |
| tree | 2fceeab99e34a3b57eb2f930866ff402ea2fa372 /drivers/phy/amlogic | |
| parent | 46e994717807f4b935c44d81dde9dd8bcd9a4f5d (diff) | |
| download | lwn-9a8406ba1a9a2965c27e0db1d7753471d12ee9ff.tar.gz lwn-9a8406ba1a9a2965c27e0db1d7753471d12ee9ff.zip | |
phy: dphy: Correct clk_pre parameter
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 <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>
Diffstat (limited to 'drivers/phy/amlogic')
| -rw-r--r-- | drivers/phy/amlogic/phy-meson-axg-mipi-dphy.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/phy/amlogic/phy-meson-axg-mipi-dphy.c b/drivers/phy/amlogic/phy-meson-axg-mipi-dphy.c index cd2332bf0e31..fdbd64c03e12 100644 --- a/drivers/phy/amlogic/phy-meson-axg-mipi-dphy.c +++ b/drivers/phy/amlogic/phy-meson-axg-mipi-dphy.c @@ -9,6 +9,7 @@ #include <linux/bitfield.h> #include <linux/bitops.h> +#include <linux/bits.h> #include <linux/clk.h> #include <linux/delay.h> #include <linux/io.h> @@ -250,7 +251,7 @@ 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) | |