On Wed, Oct 02, 2013 at 03:03:43PM -0700, Francisco Jerez wrote:
> Otherwise using any atomic memory operation will lock up the GPU due
> to a Haswell hardware bug. This patch also defines a new DRM param so
> userspace knows that atomics can be used safely.
>
> Signed-off-by: Francisco Jerez <currojerez@xxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_dma.c | 3 +++
> drivers/gpu/drm/i915/i915_reg.h | 7 +++++++
> drivers/gpu/drm/i915/intel_pm.c | 6 ++++++
> include/uapi/drm/i915_drm.h | 1 +
> 4 files changed, 17 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index c27a210..e4fcb3d 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -1003,6 +1003,9 @@ static int i915_getparam(struct drm_device *dev, void *data,
> case I915_PARAM_HAS_EXEC_HANDLE_LUT:
> value = 1;
> break;
> + case I915_PARAM_HAS_ATOMICS:
> + value = 1;
> + break;
> default:
> DRM_DEBUG("Unknown parameter %d\n", param->param);
> return -EINVAL;
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index c159e1a..611a863 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -3881,6 +3881,9 @@
> #define GEN7_SQ_CHICKEN_MBCUNIT_CONFIG 0x9030
> #define GEN7_SQ_CHICKEN_MBCUNIT_SQINTMOB (1<<11)
>
> +#define HSW_SCRATCH1 0xb038
> +#define HSW_SCRATCH1_L3_DATA_ATOMICS_DISABLE (1<<27)
> +
> #define HSW_FUSE_STRAP 0x42014
> #define HSW_CDCLK_LIMIT (1 << 24)
>
> @@ -4728,6 +4731,10 @@
> #define GEN7_ROW_CHICKEN2_GT2 0xf4f4
> #define DOP_CLOCK_GATING_DISABLE (1<<0)
>
> +#define HSW_ROW_CHICKEN3 0xe49c
> +#define HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_MASK (1 << 22)
> +#define HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE (1 << 6)
> +
You do not need the mask bit. We have macros for this:
_MASKED_BIT_ENABLE
> #define G4X_AUD_VID_DID (dev_priv->info->display_mmio_offset + 0x62020)
> #define INTEL_AUDIO_DEVCL 0x808629FB
> #define INTEL_AUDIO_DEVBLC 0x80862801
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index dd176b7..47f2b2f 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -4955,6 +4955,12 @@ static void haswell_init_clock_gating(struct drm_device *dev)
> I915_WRITE(GEN7_L3_CHICKEN_MODE_REGISTER,
> GEN7_WA_L3_CHICKEN_MODE);
>
> + /* L3 caching of data atomics doesn't work -- disable it. */
> + I915_WRITE(HSW_SCRATCH1, HSW_SCRATCH1_L3_DATA_ATOMICS_DISABLE);
> + I915_WRITE(HSW_ROW_CHICKEN3,
> + HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_MASK |
> + HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE);
> +
> /* This is required by WaCatErrorRejectionIssue:hsw */
> I915_WRITE(GEN7_SQ_CHICKEN_MBCUNIT_CONFIG,
> I915_READ(GEN7_SQ_CHICKEN_MBCUNIT_CONFIG) |
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index 55bb572..fe0f52e 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -335,6 +335,7 @@ typedef struct drm_i915_irq_wait {
> #define I915_PARAM_HAS_EXEC_NO_RELOC 25
> #define I915_PARAM_HAS_EXEC_HANDLE_LUT 26
> #define I915_PARAM_HAS_WT 27
> +#define I915_PARAM_HAS_ATOMICS 28
>
> typedef struct drm_i915_getparam {
> int param;
Also, AFAIK, this workaround still isn't in the bspec, so I think it's a
bit hard for people to review. I'd prefer if we had the bspec updated,
but since they're moving so slowly, and I have the context:
Reviewed-by: Ben Widawsky <ben@xxxxxxxxxxxx>
--
Ben Widawsky, Intel Open Source Technology Center
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