diff options
| -rw-r--r-- | drivers/gpu/drm/pl111/pl111_display.c | 29 | ||||
| -rw-r--r-- | include/linux/amba/clcd-regs.h | 1 |
2 files changed, 28 insertions, 2 deletions
diff --git a/drivers/gpu/drm/pl111/pl111_display.c b/drivers/gpu/drm/pl111/pl111_display.c index 9a153125e5d2..024771a4083e 100644 --- a/drivers/gpu/drm/pl111/pl111_display.c +++ b/drivers/gpu/drm/pl111/pl111_display.c @@ -128,6 +128,7 @@ static void pl111_display_enable(struct drm_simple_display_pipe *pipe, struct drm_framebuffer *fb = plane->state->fb; struct drm_connector *connector = priv->connector; struct drm_bridge *bridge = priv->bridge; + bool grayscale = false; u32 cntl; u32 ppl, hsw, hfp, hbp; u32 lpp, vsw, vfp, vbp; @@ -187,6 +188,20 @@ static void pl111_display_enable(struct drm_simple_display_pipe *pipe, if (connector->display_info.bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE) tim2 |= TIM2_IPC; + + if (connector->display_info.num_bus_formats == 1 && + connector->display_info.bus_formats[0] == + MEDIA_BUS_FMT_Y8_1X8) + grayscale = true; + + /* + * The AC pin bias frequency is set to max count when using + * grayscale so at least once in a while we will reverse + * polarity and get rid of any DC built up that could + * damage the display. + */ + if (grayscale) + tim2 |= TIM2_ACB_MASK; } if (bridge) { @@ -218,8 +233,18 @@ static void pl111_display_enable(struct drm_simple_display_pipe *pipe, writel(0, priv->regs + CLCD_TIM3); - /* Hard-code TFT panel */ - cntl = CNTL_LCDEN | CNTL_LCDTFT | CNTL_LCDVCOMP(1); + /* + * Detect grayscale bus format. We do not support a grayscale mode + * toward userspace, instead we expose an RGB24 buffer and then the + * hardware will activate its grayscaler to convert to the grayscale + * format. + */ + if (grayscale) + cntl = CNTL_LCDEN | CNTL_LCDMONO8; + else + /* Else we assume TFT display */ + cntl = CNTL_LCDEN | CNTL_LCDTFT | CNTL_LCDVCOMP(1); + /* On the ST Micro variant, assume all 24 bits are connected */ if (priv->variant->st_bitmux_control) cntl |= CNTL_ST_CDWID_24; diff --git a/include/linux/amba/clcd-regs.h b/include/linux/amba/clcd-regs.h index 516a6fda83c5..421b0fa90d6a 100644 --- a/include/linux/amba/clcd-regs.h +++ b/include/linux/amba/clcd-regs.h @@ -42,6 +42,7 @@ #define TIM2_PCD_LO_MASK GENMASK(4, 0) #define TIM2_PCD_LO_BITS 5 #define TIM2_CLKSEL (1 << 5) +#define TIM2_ACB_MASK GENMASK(10, 6) #define TIM2_IVS (1 << 11) #define TIM2_IHS (1 << 12) #define TIM2_IPC (1 << 13) |