[PATCH 01/12] drm/i915: Fix forcewake counts for gen8

Ben Widawsky
2014-03-21T18:48:10Z

From: Mika Kuoppala <mika.kuoppala@linux.intel.com>

Sometimes generic driver code gets forcewake explicitly by
gen6_gt_force_wake_get(), which check forcewake_count before accessing
hardware. However the register access with gen8_write function access
low level hw accessors directly, ignoring the forcewake_count. This
leads to nested forcewake get from hardware, in ring init and possibly
elsewhere, causing forcewake ack clear errors and/or hangs.

Fix this by checking the forcewake count also in gen8_write

v2: Read side doesn't care about shadowed registers,
Remove __needs_put funkiness from gen8_write. (Ville)
Improved commit message.

References: https://bugs.freedesktop.org/show_bug.cgi?id=74007
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
[BDW 3.14 backport]
Cc: stable@vger.kernel.org
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
---
drivers/gpu/drm/i915/intel_uncore.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index 87df68f..6df5ec4 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -634,16 +634,17 @@ static bool is_gen8_shadowed(struct drm_i915_private *dev_priv, u32 reg)
#define __gen8_write(x) \
static void \
gen8_write##x(struct drm_i915_private *dev_priv, off_t reg, u##x val, bool trace) { \
- bool __needs_put = reg < 0x40000 && !is_gen8_shadowed(dev_priv, reg); \
REG_WRITE_HEADER; \
- if (__needs_put) { \
- dev_priv->uncore.funcs.force_wake_get(dev_priv, \
- FORCEWAKE_ALL); \
- } \
- __raw_i915_write##x(dev_priv, reg, val); \
- if (__needs_put) { \
- dev_priv->uncore.funcs.force_wake_put(dev_priv, \
- FORCEWAKE_ALL); \
+ if (reg < 0x40000 && !is_gen8_shadowed(dev_priv, reg)) { \
+ if (dev_priv->uncore.forcewake_count == 0) \
+ dev_priv->uncore.funcs.force_wake_get(dev_priv, \
+ FORCEWAKE_ALL); \
+ __raw_i915_write##x(dev_priv, reg, val); \
+ if (dev_priv->uncore.forcewake_count == 0) \
+ dev_priv->uncore.funcs.force_wake_put(dev_priv, \
+ FORCEWAKE_ALL); \
+ } else { \
+ __raw_i915_write##x(dev_priv, reg, val); \
} \
REG_WRITE_FOOTER; \
}
--
1.9.1