diff options
Diffstat (limited to 'drivers/gpu/drm/i915/i915_drv.h')
| -rw-r--r-- | drivers/gpu/drm/i915/i915_drv.h | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 757b1d1b9366..ecfd8e9726b5 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -579,8 +579,6 @@ struct intel_uncore_funcs { uint16_t val, bool trace); void (*mmio_writel)(struct drm_i915_private *dev_priv, i915_reg_t r, uint32_t val, bool trace); - void (*mmio_writeq)(struct drm_i915_private *dev_priv, i915_reg_t r, - uint64_t val, bool trace); }; struct intel_uncore { @@ -3758,9 +3756,16 @@ int intel_freq_opcode(struct drm_i915_private *dev_priv, int val); * will be implemented using 2 32-bit writes in an arbitrary order with * an arbitrary delay between them. This can cause the hardware to * act upon the intermediate value, possibly leading to corruption and - * machine death. You have been warned. + * machine death. For this reason we do not support I915_WRITE64, or + * dev_priv->uncore.funcs.mmio_writeq. + * + * When reading a 64-bit value as two 32-bit values, the delay may cause + * the two reads to mismatch, e.g. a timestamp overflowing. Also note that + * occasionally a 64-bit register does not actualy support a full readq + * and must be read using two 32-bit reads. + * + * You have been warned. */ -#define I915_WRITE64(reg, val) dev_priv->uncore.funcs.mmio_writeq(dev_priv, (reg), (val), true) #define I915_READ64(reg) dev_priv->uncore.funcs.mmio_readq(dev_priv, (reg), true) #define I915_READ64_2x32(lower_reg, upper_reg) ({ \ |