drm/i915: Disable M2 frac division for integer case
v2 : Handle M2 frac division for both M2 frac and int cases
v3 : Addressed Ville's review comments. Cleared the old bits for RMW
v4 : Fix feedfwd gain (Ville)
Signed-off-by: Vijay Purushothaman <vijay.a.purushothaman@linux.intel.com>
Reviewed-by: Ville Syrjala <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index c3a5888..8676cb8 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6161,6 +6161,7 @@
enum dpio_channel port = vlv_pipe_to_channel(pipe);
u32 loopfilter, intcoeff;
u32 bestn, bestm1, bestm2, bestp1, bestp2, bestm2_frac;
+ u32 dpio_val;
int refclk;
bestn = pipe_config->dpll.n;
@@ -6169,6 +6170,7 @@
bestm2 = pipe_config->dpll.m2 >> 22;
bestp1 = pipe_config->dpll.p1;
bestp2 = pipe_config->dpll.p2;
+ dpio_val = 0;
/*
* Enable Refclk and SSC
@@ -6194,12 +6196,16 @@
1 << DPIO_CHV_N_DIV_SHIFT);
/* M2 fraction division */
- vlv_dpio_write(dev_priv, pipe, CHV_PLL_DW2(port), bestm2_frac);
+ if (bestm2_frac)
+ vlv_dpio_write(dev_priv, pipe, CHV_PLL_DW2(port), bestm2_frac);
/* M2 fraction division enable */
- vlv_dpio_write(dev_priv, pipe, CHV_PLL_DW3(port),
- DPIO_CHV_FRAC_DIV_EN |
- (2 << DPIO_CHV_FEEDFWD_GAIN_SHIFT));
+ dpio_val = vlv_dpio_read(dev_priv, pipe, CHV_PLL_DW3(port));
+ dpio_val &= ~(DPIO_CHV_FEEDFWD_GAIN_MASK | DPIO_CHV_FRAC_DIV_EN);
+ dpio_val |= (2 << DPIO_CHV_FEEDFWD_GAIN_SHIFT);
+ if (bestm2_frac)
+ dpio_val |= DPIO_CHV_FRAC_DIV_EN;
+ vlv_dpio_write(dev_priv, pipe, CHV_PLL_DW3(port), dpio_val);
/* Loop filter */
refclk = i9xx_get_refclk(crtc, 0);