[ Upstream commit 85fb352666732a9e5caf6027b9c253b3d7881d8f ]

The current code allows the TCON clock divider to have a range between 4
and 127 when feeding the DSI controller.

The only display supported so far had a display clock rate that ended up
using a divider of 4, but testing with other displays show that only 4
seems to be functional.

This also aligns with what Allwinner is doing in their BSP, so let's just
hardcode that we want a divider of 4 when using the DSI output.

Reviewed-by: Paul Kocialkowski <paul.kocialkow...@bootlin.com>
Signed-off-by: Maxime Ripard <maxime.rip...@bootlin.com>
Link: 
https://patchwork.freedesktop.org/patch/msgid/074e88ae472f5e0492e26939c74b44fb4125ffbd.1549896081.git-series.maxime.rip...@bootlin.com
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 drivers/gpu/drm/sun4i/sun4i_tcon.c     | 4 ++--
 drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h | 2 ++
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c 
b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index 7136fc91c6036..e75f77ff8e0fc 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
@@ -341,8 +341,8 @@ static void sun4i_tcon0_mode_set_cpu(struct sun4i_tcon 
*tcon,
        u32 block_space, start_delay;
        u32 tcon_div;
 
-       tcon->dclk_min_div = 4;
-       tcon->dclk_max_div = 127;
+       tcon->dclk_min_div = SUN6I_DSI_TCON_DIV;
+       tcon->dclk_max_div = SUN6I_DSI_TCON_DIV;
 
        sun4i_tcon0_mode_set_common(tcon, mode);
 
diff --git a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h 
b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h
index a07090579f84b..5c3ad5be06901 100644
--- a/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h
+++ b/drivers/gpu/drm/sun4i/sun6i_mipi_dsi.h
@@ -13,6 +13,8 @@
 #include <drm/drm_encoder.h>
 #include <drm/drm_mipi_dsi.h>
 
+#define SUN6I_DSI_TCON_DIV     4
+
 struct sun6i_dsi {
        struct drm_connector    connector;
        struct drm_encoder      encoder;
-- 
2.20.1



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