In sam9x7 SoC where XLCDC IP is used,add support to bypass the LCDC pixel
clock divider when LCDC Generic clock is enabled.Used to match
and drive the panel requested Pixel clock.

Signed-off-by: Manikandan Muralidharan <[email protected]>
---
 drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c | 8 +++++++-
 include/linux/mfd/atmel-hlcdc.h                | 1 +
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c 
b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
index 0f7ffb3ced20..c54770cecaa8 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c
@@ -146,13 +146,19 @@ static void atmel_hlcdc_crtc_mode_set_nofb(struct 
drm_crtc *c)
 
                if (div_low >= 2 &&
                    (10 * (prate / div_low - mode_rate) <
-                    (mode_rate - prate / div)))
+                    (mode_rate - prate / div))) {
                        /*
                         * At least 10 times better when using a higher
                         * frequency than requested, instead of a lower.
                         * So, go with that.
                         */
                        div = div_low;
+               } else {
+                       if (crtc->dc->desc->is_xlcdc) {
+                               cfg |= ATMEL_XLCDC_CLKBYP;
+                               mask |= ATMEL_XLCDC_CLKBYP;
+                       }
+               }
        }
 
        cfg |= ATMEL_HLCDC_CLKDIV(div);
diff --git a/include/linux/mfd/atmel-hlcdc.h b/include/linux/mfd/atmel-hlcdc.h
index 80d675a03b39..982f494e6307 100644
--- a/include/linux/mfd/atmel-hlcdc.h
+++ b/include/linux/mfd/atmel-hlcdc.h
@@ -44,6 +44,7 @@
 #define ATMEL_XLCDC_HEO_UPDATE         BIT(3)
 
 #define ATMEL_HLCDC_CLKPOL             BIT(0)
+#define ATMEL_XLCDC_CLKBYP             BIT(1)
 #define ATMEL_HLCDC_CLKSEL             BIT(2)
 #define ATMEL_HLCDC_CLKPWMSEL          BIT(3)
 #define ATMEL_HLCDC_CGDIS(i)           BIT(8 + (i))
-- 
2.25.1

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