On Fri, Jul 17, 2015 at 07:13:32PM +0100, Arun Siluvery wrote:
> The Golden batch carries 3D state at the beginning so that HW starts with
> a known state. It is carried as a binary blob which is auto-generated from
> source. The idea was it would be easier to maintain and keep the complexity
> out of the kernel which makes sense as we don't really touch it. However if
> you really need to update it then you need to update generator source and
> keep the binary blob in sync with it.
>
> There is a need to patch this in bxt to send one additional command to enable
> a feature. A solution was to patch the binary data with some additional
> data structures (included as part of auto-generator source) but it was
> unnecessarily complicated.
>
> Chris suggested the idea of having a secondary batch and execute two batch
> buffers. It has clear advantages as we needn't touch the base golden batch,
> can customize secondary/auxiliary batch depending on Gen and can be carried
> in the driver with no dependencies.
>
> This patch adds support for this auxiliary batch which is inserted at the
> end of golden batch and is completely independent from it. Thanks to Mika
> for the preliminary review.
>
> v2: Strictly conform to the batch size requirements to cover Gen2 and
> add comments to clarify overflow check in macro (Chris, Mika).
>
> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Armin Reese <armin.c.reese@xxxxxxxxx>
> Signed-off-by: Arun Siluvery <arun.siluvery@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_gem_render_state.c | 45 ++++++++++++++++++++++++++++
> drivers/gpu/drm/i915/i915_gem_render_state.h | 2 ++
> drivers/gpu/drm/i915/intel_lrc.c | 6 ++++
> 3 files changed, 53 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_render_state.c b/drivers/gpu/drm/i915/i915_gem_render_state.c
> index b6492fe..5026a62 100644
> --- a/drivers/gpu/drm/i915/i915_gem_render_state.c
> +++ b/drivers/gpu/drm/i915/i915_gem_render_state.c
> @@ -73,6 +73,24 @@ free_gem:
> return ret;
> }
>
> +/*
> + * Macro to add commands to auxiliary batch.
> + * This macro only checks for page overflow before inserting the commands,
> + * this is sufficient as the null state generator makes the final batch
> + * with two passes to build command and state separately. At this point
> + * the size of both are known and it compacts them by relocating the state
> + * right after the commands taking care of aligment so we should sufficient
> + * space below them for adding new commands.
> + */
> +#define OUT_BATCH(batch, i, val) \
> + do { \
> + if (WARN_ON((i) >= PAGE_SIZE / sizeof(u32))) { \
> + ret = -ENOSPC; \
> + goto err_out; \
> + } \
> + (batch)[(i)++] = (val); \
> + } while(0)
> +
> static int render_state_setup(struct render_state *so)
> {
> const struct intel_renderstate_rodata *rodata = so->rodata;
> @@ -110,6 +128,21 @@ static int render_state_setup(struct render_state *so)
>
> d[i++] = s;
> }
> +
> + while (i % CACHELINE_DWORDS)
> + OUT_BATCH(d, i, MI_NOOP);
> +
> + so->aux_batch_offset = i * sizeof(u32);
> +
> + OUT_BATCH(d, i, MI_BATCH_BUFFER_END);
> + so->aux_batch_size = (i * sizeof(u32)) - so->aux_batch_offset;
> +
> + /*
> + * Since we are sending length, we need to strictly conform to
> + * all requirements. For Gen2 this must be a multiple of 8.
> + */
> + so->aux_batch_size = ALIGN(so->aux_batch_size, 8);
> +
> kunmap(page);
>
> ret = i915_gem_object_set_to_gtt_domain(so->obj, false);
> @@ -128,6 +161,8 @@ err_out:
> return ret;
> }
>
> +#undef OUT_BATCH
> +
> void i915_gem_render_state_fini(struct render_state *so)
> {
> i915_gem_object_ggtt_unpin(so->obj);
> @@ -176,6 +211,16 @@ int i915_gem_render_state_init(struct drm_i915_gem_request *req)
> if (ret)
> goto out;
>
> + if (so.aux_batch_size > 8) {
> + ret = req->ring->dispatch_execbuffer(req,
> + (so.ggtt_offset +
> + so.aux_batch_offset),
> + so.aux_batch_size,
> + I915_DISPATCH_SECURE);
> + if (ret)
> + goto out;
> + }
> +
> i915_vma_move_to_active(i915_gem_obj_to_ggtt(so.obj), req);
>
> out:
> diff --git a/drivers/gpu/drm/i915/i915_gem_render_state.h b/drivers/gpu/drm/i915/i915_gem_render_state.h
> index 7aa7372..79de101 100644
> --- a/drivers/gpu/drm/i915/i915_gem_render_state.h
> +++ b/drivers/gpu/drm/i915/i915_gem_render_state.h
> @@ -37,6 +37,8 @@ struct render_state {
> struct drm_i915_gem_object *obj;
> u64 ggtt_offset;
> int gen;
> + u32 aux_batch_size;
> + u64 aux_batch_offset;
u64!!!! That's a mighty big page.
>From a code inspection pov, you've addressed all of my concerns (and it
would be nice to fixup that rogue u64 above).
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
for the series
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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