[PATCH 1/4] drm/sun4i: dsi: Restrict DSI tcon clock divider

[Maxime Ripard]

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.

Signed-off-by: Maxime Ripard <maxime.ripard at bootlin.com>
---
 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 0420f5c978b9..bee73ead732a 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 dbbc5b3ecbda..6d4a3c0fd9b5 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_dphy {
 	struct clk		*bus_clk;
 	struct clk		*mod_clk;
-- 
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