drm/i915: rewrite the LCPLL code
Right now, we're trying to enable LCPLL at every mode set, but we're
never disabling it. Also, we really don't want to be disabling LCPLL
since it requires a very complex disable/enable sequence. This
register should really be set by the BIOS and we shouldn't be touching
it. Still, let's try to check its value and print some errors in case
we find something wrong. We're also adding intel_ddi_get_cdclk_freq
which will be used later in other places.
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index bfe3754..187ea3b 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -682,12 +682,6 @@
DRM_DEBUG_KMS("WR PLL: %dKHz refresh rate with p=%d, n2=%d r2=%d\n",
crtc->mode.clock, p, n2, r2);
- /* Enable LCPLL if disabled */
- temp = I915_READ(LCPLL_CTL);
- if (temp & LCPLL_PLL_DISABLE)
- I915_WRITE(LCPLL_CTL,
- temp & ~LCPLL_PLL_DISABLE);
-
/* Configure WR PLL 1, program the correct divider values for
* the desired frequency and wait for warmup */
I915_WRITE(WRPLL_CTL1,
@@ -817,3 +811,34 @@
I915_WRITE(DDI_BUF_CTL(port), temp);
}
+
+static int intel_ddi_get_cdclk_freq(struct drm_i915_private *dev_priv)
+{
+ if (I915_READ(HSW_FUSE_STRAP) & HSW_CDCLK_LIMIT)
+ return 450;
+ else if ((I915_READ(LCPLL_CTL) & LCPLL_CLK_FREQ_MASK) ==
+ LCPLL_CLK_FREQ_450)
+ return 450;
+ else
+ return 540;
+}
+
+void intel_ddi_pll_init(struct drm_device *dev)
+{
+ struct drm_i915_private *dev_priv = dev->dev_private;
+ uint32_t val = I915_READ(LCPLL_CTL);
+
+ /* The LCPLL register should be turned on by the BIOS. For now let's
+ * just check its state and print errors in case something is wrong.
+ * Don't even try to turn it on.
+ */
+
+ DRM_DEBUG_KMS("CDCLK running at %dMHz\n",
+ intel_ddi_get_cdclk_freq(dev_priv));
+
+ if (val & LCPLL_CD_SOURCE_FCLK)
+ DRM_ERROR("CDCLK source is not LCPLL\n");
+
+ if (val & LCPLL_PLL_DISABLE)
+ DRM_ERROR("LCPLL is disabled\n");
+}