While reading docs I've noticed that this special workaround to select
the 1.6 GHz DP clock only applies to pre-production ilk machines.
Since the registers we're touching here are rather undocumented and
might be harmful on later chips, rip it out.
For the Bspec reference of this w/a look in "vol4g CPU Display
Registers [DevILK]", Section 4.1.7.1 "DP_A?DisplayPort A
Control Register", "DP_PLL_Frequency_Select".
v2: Keep a debug message as a hint in case something regresses.
Requested by Chris Wilson.
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
drivers/gpu/drm/i915/intel_dp.c | 21 +++++----------------
1 file changed, 5 insertions(+), 16 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index e5f496b..b2aa666 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -862,26 +862,15 @@ static void ironlake_set_pll_edp(struct drm_crtc *crtc, int clock)
dpa_ctl &= ~DP_PLL_FREQ_MASK;
if (clock < 200000) {
- u32 temp;
+ /* For a long time we've carried around a ILK-DevA w/a for the
+ * 160MHz clock. If we're really unlucky, it's still required.
+ */
+ DRM_DEBUG_KMS("160MHz cpu eDP clock, might need ilk devA w/a\n");
dpa_ctl |= DP_PLL_FREQ_160MHZ;
- /* workaround for 160Mhz:
- 1) program 0x4600c bits 15:0 = 0x8124
- 2) program 0x46010 bit 0 = 1
- 3) program 0x46034 bit 24 = 1
- 4) program 0x64000 bit 14 = 1
- */
- temp = I915_READ(0x4600c);
- temp &= 0xffff0000;
- I915_WRITE(0x4600c, temp | 0x8124);
-
- temp = I915_READ(0x46010);
- I915_WRITE(0x46010, temp | 1);
-
- temp = I915_READ(0x46034);
- I915_WRITE(0x46034, temp | (1 << 24));
} else {
dpa_ctl |= DP_PLL_FREQ_270MHZ;
}
+
I915_WRITE(DP_A, dpa_ctl);
POSTING_READ(DP_A);
--
1.7.11.7
