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. And, the kernel doc of the 'clk_pre' member wrongly says the minimum value is '8 UI', instead of 8.

So, let's fix both the dphy core driver and the kernel doc of the 'clk_pre' member to correctly reflect the T-CLK-PRE parameter's unit and the 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") Cc: Andrzej Hajda andrzej.hajda@intel.com Cc: Neil Armstrong narmstrong@baylibre.com Cc: Robert Foss robert.foss@linaro.org Cc: Laurent Pinchart Laurent.pinchart@ideasonboard.com Cc: Jonas Karlman jonas@kwiboo.se Cc: Jernej Skrabec jernej.skrabec@gmail.com Cc: David Airlie airlied@linux.ie Cc: Daniel Vetter daniel@ffwll.ch Cc: Kishon Vijay Abraham I kishon@ti.com Cc: Vinod Koul vkoul@kernel.org Cc: Kevin Hilman khilman@baylibre.com Cc: Jerome Brunet jbrunet@baylibre.com Cc: Martin Blumenstingl martin.blumenstingl@googlemail.com Cc: Heiko Stuebner heiko@sntech.de Cc: Maxime Ripard mripard@kernel.org Cc: Guido Günther agx@sigxcpu.org Cc: Wyon Bi bivvy.bi@rock-chips.com 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 --- v2->v3: * Drop D-PHY documentation change. (Laurent) * Collect R-b tags and T-b tags. * Cc Wyon.

v1->v2: * Use BITS_PER_BYTE macro. (Andrzej) * Drop dsi argument from ui2bc() in nwl-dsi.c.

drivers/gpu/drm/bridge/nwl-dsi.c | 12 +++++------- drivers/phy/amlogic/phy-meson-axg-mipi-dphy.c | 3 ++- drivers/phy/phy-core-mipi-dphy.c | 4 ++-- drivers/phy/rockchip/phy-rockchip-inno-dsidphy.c | 3 ++- 4 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c index a7389a0facfb..af07eeb47ca0 100644 --- a/drivers/gpu/drm/bridge/nwl-dsi.c +++ b/drivers/gpu/drm/bridge/nwl-dsi.c @@ -7,6 +7,7 @@ */

#include <linux/bitfield.h> +#include <linux/bits.h> #include <linux/clk.h> #include <linux/irq.h> #include <linux/math64.h> @@ -196,12 +197,9 @@ static u32 ps2bc(struct nwl_dsi *dsi, unsigned long long ps) /* * ui2bc - UI time periods to byte clock cycles */ -static u32 ui2bc(struct nwl_dsi *dsi, unsigned long long ui) +static u32 ui2bc(unsigned int ui) { - u32 bpp = mipi_dsi_pixel_format_to_bpp(dsi->format); - - return DIV64_U64_ROUND_UP(ui * dsi->lanes, - dsi->mode.clock * 1000 * bpp); + return DIV_ROUND_UP(ui, BITS_PER_BYTE); }

/* @@ -232,12 +230,12 @@ static int nwl_dsi_config_host(struct nwl_dsi *dsi) }

/* values in byte clock cycles */ - cycles = ui2bc(dsi, cfg->clk_pre); + cycles = ui2bc(cfg->clk_pre); DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_t_pre: 0x%x\n", cycles); nwl_dsi_write(dsi, NWL_DSI_CFG_T_PRE, cycles); cycles = ps2bc(dsi, cfg->lpx + cfg->clk_prepare + cfg->clk_zero); DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_tx_gap (pre): 0x%x\n", cycles); - cycles += ui2bc(dsi, cfg->clk_pre); + cycles += ui2bc(cfg->clk_pre); DRM_DEV_DEBUG_DRIVER(dsi->dev, "cfg_t_post: 0x%x\n", cycles); nwl_dsi_write(dsi, NWL_DSI_CFG_T_POST, cycles); cycles = ps2bc(dsi, cfg->hs_exit); 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) | 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) diff --git a/drivers/phy/rockchip/phy-rockchip-inno-dsidphy.c b/drivers/phy/rockchip/phy-rockchip-inno-dsidphy.c index 347dc79a18c1..630e01b5c19b 100644 --- a/drivers/phy/rockchip/phy-rockchip-inno-dsidphy.c +++ b/drivers/phy/rockchip/phy-rockchip-inno-dsidphy.c @@ -5,6 +5,7 @@ * Author: Wyon Bi bivvy.bi@rock-chips.com */

+#include <linux/bits.h> #include <linux/kernel.h> #include <linux/clk.h> #include <linux/iopoll.h> @@ -364,7 +365,7 @@ static void inno_dsidphy_mipi_mode_enable(struct inno_dsidphy *inno) * The value of counter for HS Tclk-pre * Tclk-pre = Tpin_txbyteclkhs * value */ - clk_pre = DIV_ROUND_UP(cfg->clk_pre, t_txbyteclkhs); + clk_pre = DIV_ROUND_UP(cfg->clk_pre, BITS_PER_BYTE);

/* * The value of counter for HS Tlpx Time