Re: [PATCH v6 5/6] drm/i915/gen8: Add WaClearSlmSpaceAtContextSwitch workaround

Daniel Vetter
2015-06-22T15:36:43Z

On Mon, Jun 22, 2015 at 12:29:05PM +0100, Siluvery, Arun wrote:
> On 19/06/2015 19:09, Chris Wilson wrote:
> >On Fri, Jun 19, 2015 at 06:37:14PM +0100, Arun Siluvery wrote:
> >>In Indirect context w/a batch buffer,
> >>WaClearSlmSpaceAtContextSwitch
> >>
> >>This WA performs writes to scratch page so it must be valid, this check
> >>is performed before initializing the batch with this WA.
> >>
> >>v2: s/PIPE_CONTROL_FLUSH_RO_CACHES/PIPE_CONTROL_FLUSH_L3 (Ville)
> >>
> >>Cc: Chris Wilson <chris@chris-wilson.co.uk>
> >>Cc: Dave Gordon <david.s.gordon@intel.com>
> >>Signed-off-by: Rafael Barbalho <rafael.barbalho@intel.com>
> >>Signed-off-by: Arun Siluvery <arun.siluvery@linux.intel.com>
> >>---
> >> drivers/gpu/drm/i915/i915_reg.h | 1 +
> >> drivers/gpu/drm/i915/intel_lrc.c | 16 ++++++++++++++++
> >> 2 files changed, 17 insertions(+)
> >>
> >>diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> >>index d14ad20..7637e64 100644
> >>--- a/drivers/gpu/drm/i915/i915_reg.h
> >>+++ b/drivers/gpu/drm/i915/i915_reg.h
> >>@@ -410,6 +410,7 @@
> >> #define DISPLAY_PLANE_A (0<<20)
> >> #define DISPLAY_PLANE_B (1<<20)
> >> #define GFX_OP_PIPE_CONTROL(len) ((0x3<<29)|(0x3<<27)|(0x2<<24)|(len-2))
> >>+#define PIPE_CONTROL_FLUSH_L3 (1<<27)
> >> #define PIPE_CONTROL_GLOBAL_GTT_IVB (1<<24) /* gen7+ */
> >> #define PIPE_CONTROL_MMIO_WRITE (1<<23)
> >> #define PIPE_CONTROL_STORE_DATA_INDEX (1<<21)
> >>diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> >>index 3e7aaa9..664455c 100644
> >>--- a/drivers/gpu/drm/i915/intel_lrc.c
> >>+++ b/drivers/gpu/drm/i915/intel_lrc.c
> >>@@ -1137,6 +1137,7 @@ static int gen8_init_indirectctx_bb(struct intel_engine_cs *ring,
> >> uint32_t *const batch,
> >> uint32_t *offset)
> >> {
> >>+ uint32_t scratch_addr;
> >> uint32_t index = wa_ctx_start(wa_ctx, *offset, CACHELINE_DWORDS);
> >>
> >> /* WaDisableCtxRestoreArbitration:bdw,chv */
> >>@@ -1165,6 +1166,21 @@ static int gen8_init_indirectctx_bb(struct intel_engine_cs *ring,
> >> wa_ctx_emit(batch, l3sqc4_flush & ~GEN8_LQSC_FLUSH_COHERENT_LINES);
> >> }
> >>
> >>+ /* WaClearSlmSpaceAtContextSwitch:bdw,chv */
> >>+ /* Actual scratch location is at 128 bytes offset */
> >>+ scratch_addr = ring->scratch.gtt_offset + 2*CACHELINE_BYTES;
> >>+ scratch_addr |= PIPE_CONTROL_GLOBAL_GTT;
> >
> >I thought this bit was now mbz - that's how we treat it elsewhere e.g.
> >gen8_emit_flush_render, and that the address has to be naturally aligned
> >for the target write. (Similar bit in patch 6 fwiw.)
> you are correct, this bit is mbz.
>
> Daniel, could you please remove this line when applying patches?
> sorry for additional work.
>
> >> + scratch_addr |= PIPE_CONTROL_GLOBAL_GTT;

Since you need to send out a follow-up anyway, can you pls do that when
resending? I'm still applying all the other ones.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation