diff mbox

drm/sun4i: tcon: Add dithering support for RGB565/RGB666 LCD panels

Message ID 20171017110946.18961-1-net147@gmail.com (mailing list archive)
State New, archived
Headers show

Commit Message

Jonathan Liu Oct. 17, 2017, 11:09 a.m. UTC
Dithering is supported on TCON channel 0 which is used for LCD panels.

Signed-off-by: Jonathan Liu <net147@gmail.com>
---
 drivers/gpu/drm/sun4i/sun4i_tcon.c | 37 +++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/sun4i/sun4i_tcon.h | 18 +++++++++++++++++-
 2 files changed, 54 insertions(+), 1 deletion(-)

Comments

Maxime Ripard Oct. 17, 2017, 7:46 p.m. UTC | #1
Hi,

On Tue, Oct 17, 2017 at 10:09:46PM +1100, Jonathan Liu wrote:
> Dithering is supported on TCON channel 0 which is used for LCD panels.

Expanding a bit the commit log would be great. What is dithering, why
is this needed in the first place, what is it trying to fix, etc.

> Signed-off-by: Jonathan Liu <net147@gmail.com>
> ---
>  drivers/gpu/drm/sun4i/sun4i_tcon.c | 37 +++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/sun4i/sun4i_tcon.h | 18 +++++++++++++++++-
>  2 files changed, 54 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> index 68751b999877..cf313ca858b3 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> @@ -12,11 +12,13 @@
>  
>  #include <drm/drmP.h>
>  #include <drm/drm_atomic_helper.h>
> +#include <drm/drm_connector.h>
>  #include <drm/drm_crtc.h>
>  #include <drm/drm_crtc_helper.h>
>  #include <drm/drm_encoder.h>
>  #include <drm/drm_modes.h>
>  #include <drm/drm_of.h>
> +#include <drm/drm_panel.h>
>  
>  #include <uapi/drm/drm_mode.h>
>  
> @@ -168,7 +170,9 @@ void sun4i_tcon0_mode_set(struct sun4i_tcon *tcon,
>  			  struct drm_display_mode *mode)
>  {
>  	unsigned int bp, hsync, vsync;
> +	u32 bus_format = 0;
>  	u8 clk_delay;
> +	struct drm_connector *connector = tcon->panel->connector;

You shouldn't access the connector directly, but instead use the
current state associated to the encoder.

>  	u32 val = 0;
>  
>  	/* Configure the dot clock */
> @@ -230,6 +234,39 @@ void sun4i_tcon0_mode_set(struct sun4i_tcon *tcon,
>  			   SUN4I_TCON0_IO_POL_HSYNC_POSITIVE | SUN4I_TCON0_IO_POL_VSYNC_POSITIVE,
>  			   val);
>  
> +	if (connector->display_info.num_bus_formats)
> +		bus_format = connector->display_info.bus_formats[0];
> +
> +	switch (bus_format) {
> +	case MEDIA_BUS_FMT_RGB565_1X16:
> +	case MEDIA_BUS_FMT_RGB666_1X18:

I guess that has more to do with the bit width than the actual media
bus.

I've created helper for both these two in my LVDS patch set, you might
want to rebase on top of it.

> +		/* Enable dithering */
> +		/* FIXME: Undocumented bits */
> +		regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED0_REG, 0x11111111);
> +		regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED1_REG, 0x11111111);
> +		regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED2_REG, 0x11111111);
> +		regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED3_REG, 0x11111111);
> +		regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED4_REG, 0x11111111);
> +		regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED5_REG, 0x11111111);
> +		regmap_write(tcon->regs, SUN4I_TCON0_FRM_TAB0_REG, 0x01010000);
> +		regmap_write(tcon->regs, SUN4I_TCON0_FRM_TAB1_REG, 0x15151111);
> +		regmap_write(tcon->regs, SUN4I_TCON0_FRM_TAB2_REG, 0x57575555);
> +		regmap_write(tcon->regs, SUN4I_TCON0_FRM_TAB3_REG, 0x7f7f7777);
> +		val = SUN4I_TCON0_FRM_CTL_ENABLE;
> +
> +		if (bus_format == MEDIA_BUS_FMT_RGB565_1X16) {
> +			val |= SUN4I_TCON0_FRM_CTL_MODE_R;
> +			val |= SUN4I_TCON0_FRM_CTL_MODE_B;
> +		}

This can be moved to the first case in your switch, and just let it
fall through. You won't have to do a comparison twice then.

Maxime
diff mbox

Patch

diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index 68751b999877..cf313ca858b3 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
@@ -12,11 +12,13 @@ 
 
 #include <drm/drmP.h>
 #include <drm/drm_atomic_helper.h>
+#include <drm/drm_connector.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_encoder.h>
 #include <drm/drm_modes.h>
 #include <drm/drm_of.h>
+#include <drm/drm_panel.h>
 
 #include <uapi/drm/drm_mode.h>
 
@@ -168,7 +170,9 @@  void sun4i_tcon0_mode_set(struct sun4i_tcon *tcon,
 			  struct drm_display_mode *mode)
 {
 	unsigned int bp, hsync, vsync;
+	u32 bus_format = 0;
 	u8 clk_delay;
+	struct drm_connector *connector = tcon->panel->connector;
 	u32 val = 0;
 
 	/* Configure the dot clock */
@@ -230,6 +234,39 @@  void sun4i_tcon0_mode_set(struct sun4i_tcon *tcon,
 			   SUN4I_TCON0_IO_POL_HSYNC_POSITIVE | SUN4I_TCON0_IO_POL_VSYNC_POSITIVE,
 			   val);
 
+	if (connector->display_info.num_bus_formats)
+		bus_format = connector->display_info.bus_formats[0];
+
+	switch (bus_format) {
+	case MEDIA_BUS_FMT_RGB565_1X16:
+	case MEDIA_BUS_FMT_RGB666_1X18:
+		/* Enable dithering */
+		/* FIXME: Undocumented bits */
+		regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED0_REG, 0x11111111);
+		regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED1_REG, 0x11111111);
+		regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED2_REG, 0x11111111);
+		regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED3_REG, 0x11111111);
+		regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED4_REG, 0x11111111);
+		regmap_write(tcon->regs, SUN4I_TCON0_FRM_SEED5_REG, 0x11111111);
+		regmap_write(tcon->regs, SUN4I_TCON0_FRM_TAB0_REG, 0x01010000);
+		regmap_write(tcon->regs, SUN4I_TCON0_FRM_TAB1_REG, 0x15151111);
+		regmap_write(tcon->regs, SUN4I_TCON0_FRM_TAB2_REG, 0x57575555);
+		regmap_write(tcon->regs, SUN4I_TCON0_FRM_TAB3_REG, 0x7f7f7777);
+		val = SUN4I_TCON0_FRM_CTL_ENABLE;
+
+		if (bus_format == MEDIA_BUS_FMT_RGB565_1X16) {
+			val |= SUN4I_TCON0_FRM_CTL_MODE_R;
+			val |= SUN4I_TCON0_FRM_CTL_MODE_B;
+		}
+
+		regmap_write(tcon->regs, SUN4I_TCON0_FRM_CTL_REG, val);
+		break;
+	default:
+		/* Disable dithering */
+		regmap_write(tcon->regs, SUN4I_TCON0_FRM_CTL_REG, 0);
+		break;
+	}
+
 	/* Map output pins to channel 0 */
 	regmap_update_bits(tcon->regs, SUN4I_TCON_GCTL_REG,
 			   SUN4I_TCON_GCTL_IOMAP_MASK,
diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.h b/drivers/gpu/drm/sun4i/sun4i_tcon.h
index d9e1357cc8ae..d64d45144c91 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.h
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.h
@@ -31,7 +31,23 @@ 
 #define SUN4I_TCON_GINT0_VBLANK_INT(pipe)		BIT(15 - (pipe))
 
 #define SUN4I_TCON_GINT1_REG			0x8
-#define SUN4I_TCON_FRM_CTL_REG			0x10
+
+#define SUN4I_TCON0_FRM_CTL_REG			0x10
+#define SUN4I_TCON0_FRM_CTL_ENABLE			BIT(31)
+#define SUN4I_TCON0_FRM_CTL_MODE_R			BIT(6)
+#define SUN4I_TCON0_FRM_CTL_MODE_G			BIT(5)
+#define SUN4I_TCON0_FRM_CTL_MODE_B			BIT(4)
+
+#define SUN4I_TCON0_FRM_SEED0_REG		0x14
+#define SUN4I_TCON0_FRM_SEED1_REG		0x18
+#define SUN4I_TCON0_FRM_SEED2_REG		0x1c
+#define SUN4I_TCON0_FRM_SEED3_REG		0x20
+#define SUN4I_TCON0_FRM_SEED4_REG		0x24
+#define SUN4I_TCON0_FRM_SEED5_REG		0x28
+#define SUN4I_TCON0_FRM_TAB0_REG		0x2c
+#define SUN4I_TCON0_FRM_TAB1_REG		0x30
+#define SUN4I_TCON0_FRM_TAB2_REG		0x34
+#define SUN4I_TCON0_FRM_TAB3_REG		0x38
 
 #define SUN4I_TCON0_CTL_REG			0x40
 #define SUN4I_TCON0_CTL_TCON_ENABLE			BIT(31)