* [PATCH] drm/sun4i: tcon: Add dithering support for RGB565/RGB666 LCD panels
@ 2017-10-17 11:09 Jonathan Liu
2017-10-17 19:46 ` Maxime Ripard
0 siblings, 1 reply; 2+ messages in thread
From: Jonathan Liu @ 2017-10-17 11:09 UTC (permalink / raw)
To: linux-arm-kernel
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(-)
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)
--
2.14.2
^ permalink raw reply related [flat|nested] 2+ messages in thread* [PATCH] drm/sun4i: tcon: Add dithering support for RGB565/RGB666 LCD panels
2017-10-17 11:09 [PATCH] drm/sun4i: tcon: Add dithering support for RGB565/RGB666 LCD panels Jonathan Liu
@ 2017-10-17 19:46 ` Maxime Ripard
0 siblings, 0 replies; 2+ messages in thread
From: Maxime Ripard @ 2017-10-17 19:46 UTC (permalink / raw)
To: linux-arm-kernel
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
--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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