Hi Liu,
Thank you for the patch.
On Wed, Jan 19, 2022 at 10:37:14AM +0800, Liu Ying wrote:
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.
I'm not sure I'd change the kernel doc. Other fields that are documented as "Time, in picoseconds" have min/max values expressed in ps, so clk_pre, documented as "Time, in UI" doesn't appear wrong if the minimum value is "8 UI".
Otherwise, this patch looks fine to me. With or without dropping that documentation change,
Reviewed-by: Laurent Pinchart laurent.pinchart@ideasonboard.com
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 Tested-by: Liu Ying victor.liu@nxp.com # RM67191 DSI panel on i.MX8mq EVK Signed-off-by: Liu Ying victor.liu@nxp.com
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 ++- include/linux/phy/phy-mipi-dphy.h | 2 +- 5 files changed, 12 insertions(+), 12 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
diff --git a/include/linux/phy/phy-mipi-dphy.h b/include/linux/phy/phy-mipi-dphy.h index a877ffee845d..59a5e77ab409 100644 --- a/include/linux/phy/phy-mipi-dphy.h +++ b/include/linux/phy/phy-mipi-dphy.h @@ -42,7 +42,7 @@ struct phy_configure_opts_mipi_dphy { * the transmitter prior to any associated Data Lane beginning * the transition from LP to HS mode. *
* Minimum value: 8 UI
* Minimum value: 8