On Mon, Nov 25, 2013 at 09:54:33AM -0800, Ben Widawsky wrote:
> The initial implementation of this function used MMIO to write the PDPs.
> Upon review it was determined (correctly) that the docs say to use LRI.
> The issue is there are times where we want to do a synchronous write
> (GPU reset).
>
> I've tested this, and it works. I've verified with as many people as
> possible that it should work.
>
> This should fix the failing reset problems.
>
> Signed-off-by: Ben Widawsky <ben@xxxxxxxxxxxx>
This makes me nervous, for two reasons:
- Historically we've _always_ ended up in hilarity, bloodshed and tears
when having different setup/teardown code in the different parts of the
driver. Always.
- Looking at the reset code we should be initializing the rings before we
try to re-enable ppgtt. So if I don't misread stuff horribly this needs
at least one giant comment explaining what's exactly going on here -
either the hw is busted or we have some other issue.
Aside: Mika noticed that we're loosing a bunch of the w/a settings since a
few of the per-ring workarounds have been errornously put into
init_clock_gating. We need to move those to the correct per-ring init
function. This is even more important once we have per-ring reset.
Cheers, Daniel
> ---
> drivers/gpu/drm/i915/i915_gem_gtt.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 1a5272c..96dbf3d 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -197,12 +197,19 @@ static gen6_gtt_pte_t iris_pte_encode(dma_addr_t addr,
>
> /* Broadwell Page Directory Pointer Descriptors */
> static int gen8_write_pdp(struct intel_ring_buffer *ring, unsigned entry,
> - uint64_t val)
> + uint64_t val, bool synchronous)
> {
> + struct drm_i915_private *dev_priv = ring->dev->dev_private;
> int ret;
>
> BUG_ON(entry >= 4);
>
> + if (synchronous) {
> + I915_WRITE(GEN8_RING_PDP_UDW(ring, entry), val >> 32);
> + I915_WRITE(GEN8_RING_PDP_LDW(ring, entry), (u32)val);
> + return 0;
> + }
> +
> ret = intel_ring_begin(ring, 6);
> if (ret)
> return ret;
> @@ -236,7 +243,8 @@ static int gen8_ppgtt_enable(struct drm_device *dev)
> for (i = used_pd - 1; i >= 0; i--) {
> dma_addr_t addr = ppgtt->pd_dma_addr[i];
> for_each_ring(ring, dev_priv, j) {
> - ret = gen8_write_pdp(ring, i, addr);
> + ret = gen8_write_pdp(ring, i, addr,
> + i915_reset_in_progress(&dev_priv->gpu_error));
> if (ret)
> goto err_out;
> }
> --
> 1.8.4.2
>
> _______________________________________________
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--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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