The drivers current default configuration drives the pixel data on rising edge of the pixel clock. However, most display sample data on rising edge... This leads to color shift artefacts visible especially at edges.
This patch changes the relevant defines to be useful and actually set the bits, and changes pixel clock polarity to drive the pixel data on falling edge by default. The patch also adds an explicit pixel clock polarity flag to the display introduced with the driver (NEC WQVGA "nec,nl4827hc19-05b") using the new bus_flags field to retain the initial behavior.
Signed-off-by: Stefan Agner stefan@agner.ch --- drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_crtc.c | 5 +++++ drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h | 4 ++-- drivers/gpu/drm/panel/panel-simple.c | 3 ++- 3 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_crtc.c b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_crtc.c index 365809e..89c0084 100644 --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_crtc.c +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_crtc.c @@ -66,6 +66,7 @@ static void fsl_dcu_drm_crtc_mode_set_nofb(struct drm_crtc *crtc) { struct drm_device *dev = crtc->dev; struct fsl_dcu_drm_device *fsl_dev = dev->dev_private; + struct drm_connector *con = &fsl_dev->connector.base; struct drm_display_mode *mode = &crtc->state->mode; unsigned int hbp, hfp, hsw, vbp, vfp, vsw, index, pol = 0;
@@ -80,6 +81,10 @@ static void fsl_dcu_drm_crtc_mode_set_nofb(struct drm_crtc *crtc) vfp = mode->vsync_start - mode->vdisplay; vsw = mode->vsync_end - mode->vsync_start;
+ /* INV_PXCK as default (most display sample data on rising edge) */ + if (!(con->display_info.bus_flags & DRM_BUS_FLAG_PIXDATA_POSEDGE)) + pol |= DCU_SYN_POL_INV_PXCK; + if (mode->flags & DRM_MODE_FLAG_NHSYNC) pol |= DCU_SYN_POL_INV_HS_LOW;
diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h index 5bb7c26..c275f90 100644 --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h @@ -47,8 +47,8 @@ #define DCU_VSYN_PARA_FP(x) (x)
#define DCU_SYN_POL 0x0024 -#define DCU_SYN_POL_INV_PXCK_FALL (0 << 6) -#define DCU_SYN_POL_NEG_REMAIN (0 << 5) +#define DCU_SYN_POL_INV_PXCK BIT(6) +#define DCU_SYN_POL_NEG BIT(5) #define DCU_SYN_POL_INV_VS_LOW BIT(1) #define DCU_SYN_POL_INV_HS_LOW BIT(0)
diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c index 77ae07f..b19c88f 100644 --- a/drivers/gpu/drm/panel/panel-simple.c +++ b/drivers/gpu/drm/panel/panel-simple.c @@ -1053,7 +1053,8 @@ static const struct panel_desc nec_nl4827hc19_05b = { .width = 95, .height = 54, }, - .bus_format = MEDIA_BUS_FMT_RGB888_1X24 + .bus_format = MEDIA_BUS_FMT_RGB888_1X24, + .bus_flags = DRM_BUS_FLAG_PIXDATA_POSEDGE, };
static const struct display_timing okaya_rs800480t_7x0gp_timing = {