drm/i915: implement a media hang w/a

Contrary to the other clock gating w/a in GEN6_UCGCTL1, this one is
actually documented in Bspec, vol1g "GT Interface Registers [SNB]",
Section 1.5.1 "UCGCTL1 - Unit Level Clock Gating Control 1".

Supposedly this can prevent hangs on the media ring.

Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Daniel Vetter 2012-04-11 20:42:38 +02:00
parent 767878908e
commit de4a8bd162
2 changed files with 3 additions and 1 deletions

View file

@ -3893,6 +3893,7 @@
#define GEN6_UCGCTL1 0x9400
# define GEN6_BLBUNIT_CLOCK_GATE_DISABLE (1 << 5)
# define GEN6_CSUNIT_CLOCK_GATE_DISABLE (1 << 7)
#define GEN6_UCGCTL2 0x9404
# define GEN6_RCZUNIT_CLOCK_GATE_DISABLE (1 << 13)

View file

@ -8880,7 +8880,8 @@ static void gen6_init_clock_gating(struct drm_device *dev)
I915_WRITE(GEN6_UCGCTL1,
I915_READ(GEN6_UCGCTL1) |
GEN6_BLBUNIT_CLOCK_GATE_DISABLE);
GEN6_BLBUNIT_CLOCK_GATE_DISABLE |
GEN6_CSUNIT_CLOCK_GATE_DISABLE);
/* According to the BSpec vol1g, bit 12 (RCPBUNIT) clock
* gating disable must be set. Failure to set it results in