The code from [1] sets SYS_CTRL_1 to different values depending on the desired clock phase (0, 1/4, 1/2 or 3/4). A clock phase of 0 aligns the positive edge of the clock with the pixel data while other values delay the clock by a fraction of the clock period. A clock phase of 1/2 aligns the negative edge of the clock with the pixel data. The driver currently hard codes SYS_CTRL_1 to 0x88 which corresponds to aligning the positive edge of the clock with the pixel data. This won't work correctly for panels that require aligning the negative edge of the clock with the pixel data. Adjust the clock phase to 0 if DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE is present in bus_flags, otherwise adjust the clock phase to 1/2 as appropriate for DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE. [1] https://github.com/tdjastrzebski/ICN6211-Configurator Signed-off-by: Jonathan Liu <net147@xxxxxxxxx> --- V2: Use GENMASK and FIELD_PREP macros --- drivers/gpu/drm/bridge/chipone-icn6211.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/bridge/chipone-icn6211.c b/drivers/gpu/drm/bridge/chipone-icn6211.c index 47dea657a752..f1538fb5f8a9 100644 --- a/drivers/gpu/drm/bridge/chipone-icn6211.c +++ b/drivers/gpu/drm/bridge/chipone-icn6211.c @@ -9,6 +9,8 @@ #include <drm/drm_print.h> #include <drm/drm_mipi_dsi.h> +#include <linux/bitfield.h> +#include <linux/bits.h> #include <linux/delay.h> #include <linux/gpio/consumer.h> #include <linux/i2c.h> @@ -26,6 +28,11 @@ #define PD_CTRL(n) (0x0a + ((n) & 0x3)) /* 0..3 */ #define RST_CTRL(n) (0x0e + ((n) & 0x1)) /* 0..1 */ #define SYS_CTRL(n) (0x10 + ((n) & 0x7)) /* 0..4 */ +#define SYS_CTRL_1_CLK_PHASE_MSK GENMASK(5, 4) +#define CLK_PHASE_0 0 +#define CLK_PHASE_1_4 1 +#define CLK_PHASE_1_2 2 +#define CLK_PHASE_3_4 3 #define RGB_DRV(n) (0x18 + ((n) & 0x3)) /* 0..3 */ #define RGB_DLY(n) (0x1c + ((n) & 0x1)) /* 0..1 */ #define RGB_TEST_CTRL 0x1e @@ -336,7 +343,7 @@ static void chipone_atomic_enable(struct drm_bridge *bridge, const struct drm_bridge_state *bridge_state; u16 hfp, hbp, hsync; u32 bus_flags; - u8 pol, id[4]; + u8 pol, sys_ctrl_1, id[4]; chipone_readb(icn, VENDOR_ID, id); chipone_readb(icn, DEVICE_ID_H, id + 1); @@ -414,7 +421,14 @@ static void chipone_atomic_enable(struct drm_bridge *bridge, chipone_configure_pll(icn, mode); chipone_writeb(icn, SYS_CTRL(0), 0x40); - chipone_writeb(icn, SYS_CTRL(1), 0x88); + sys_ctrl_1 = 0x88; + + if (bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE) + sys_ctrl_1 |= FIELD_PREP(SYS_CTRL_1_CLK_PHASE_MSK, CLK_PHASE_0); + else + sys_ctrl_1 |= FIELD_PREP(SYS_CTRL_1_CLK_PHASE_MSK, CLK_PHASE_1_2); + + chipone_writeb(icn, SYS_CTRL(1), sys_ctrl_1); /* icn6211 specific sequence */ chipone_writeb(icn, MIPI_FORCE_0, 0x20); -- 2.36.1
