Introduce ATMEL_HLCDC_CLKDIV_MAX to replace the raw mask.In the divider
overflow fallback, restrict the clock source switch and halved rate
retry to SoCs that support the 2x system clock path.

Signed-off-by: Manikandan Muralidharan <[email protected]>
---
 drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c | 9 +++++----
 include/linux/mfd/atmel-hlcdc.h                | 1 +
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c 
b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
index f30138da1ed8..c7e77bb2941a 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
@@ -117,11 +117,12 @@ static void atmel_hlcdc_crtc_mode_set_nofb(struct 
drm_crtc *c)
                div = 2;
        } else if (ATMEL_HLCDC_CLKDIV(div) & ~ATMEL_HLCDC_CLKDIV_MASK) {
                /* The divider ended up too big, try a lower base rate. */
-               cfg &= ~ATMEL_HLCDC_CLKSEL;
-               prate /= 2;
-               div = DIV_ROUND_CLOSEST(prate, mode_rate);
+               if (!crtc->dc->desc->fixed_clksrc) {
+                       cfg &= ~ATMEL_HLCDC_CLKSEL;
+                       div = DIV_ROUND_CLOSEST(prate >> 1, mode_rate);
+               }
                if (ATMEL_HLCDC_CLKDIV(div) & ~ATMEL_HLCDC_CLKDIV_MASK)
-                       div = ATMEL_HLCDC_CLKDIV_MASK;
+                       div = ATMEL_HLCDC_CLKDIV_MAX;
        }
 
        cfg |= ATMEL_HLCDC_CLKDIV(div);
diff --git a/include/linux/mfd/atmel-hlcdc.h b/include/linux/mfd/atmel-hlcdc.h
index 07c2081867fd..8e86219293b7 100644
--- a/include/linux/mfd/atmel-hlcdc.h
+++ b/include/linux/mfd/atmel-hlcdc.h
@@ -50,6 +50,7 @@
 #define ATMEL_HLCDC_CLKDIV_SHFT                16
 #define ATMEL_HLCDC_CLKDIV_MASK                GENMASK(23, 16)
 #define ATMEL_HLCDC_CLKDIV(div)                ((div - 2) << 
ATMEL_HLCDC_CLKDIV_SHFT)
+#define ATMEL_HLCDC_CLKDIV_MAX         ((ATMEL_HLCDC_CLKDIV_MASK >> 
ATMEL_HLCDC_CLKDIV_SHFT) + 2)
 
 #define ATMEL_HLCDC_PIXEL_CLK          BIT(0)
 #define ATMEL_HLCDC_SYNC               BIT(1)
-- 
2.25.1

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