Re: [PATCH 2/5] drm/i915: Dump the ringbuffer of the active request for debugging

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Chris Wilson <chris@chris-wilson.co.uk> writes:

> Sometimes we need to see what instructions we emitted for a request to
> try and gather a glimmer of insight into what the GPU is doing when it
> stops responding.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/intel_engine_cs.c | 35 ++++++++++++++++++++++----
>  1 file changed, 30 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
> index d278fed8cb31..d7f757fb8401 100644
> --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> @@ -1443,12 +1443,10 @@ void intel_engine_dump(struct intel_engine_cs *engine,
>  
>  	rq = i915_gem_find_active_request(engine);
>  	if (rq) {
> +		void *ring;
> +		int size;
> +
>  		print_request(m, rq, "\t\tactive ");
> -		drm_printf(m,
> -			   "\t\t[head %04x, postfix %04x, tail %04x, batch 0x%08x_%08x]\n",
> -			   rq->head, rq->postfix, rq->tail,
> -			   rq->batch ? upper_32_bits(rq->batch->node.start) : ~0u,
> -			   rq->batch ? lower_32_bits(rq->batch->node.start) : ~0u);
>  		drm_printf(m, "\t\tring->start:  0x%08x\n",
>  			   i915_ggtt_offset(rq->ring->vma));
>  		drm_printf(m, "\t\tring->head:   0x%08x\n",
> @@ -1459,6 +1457,33 @@ void intel_engine_dump(struct intel_engine_cs *engine,
>  			   rq->ring->emit);
>  		drm_printf(m, "\t\tring->space:  0x%08x\n",
>  			   rq->ring->space);
> +
> +		drm_printf(m,
> +			   "[head %04x, postfix %04x, tail %04x, batch 0x%08x_%08x]:\n",
> +			   rq->head, rq->postfix, rq->tail,
> +			   rq->batch ? upper_32_bits(rq->batch->node.start) : ~0u,
> +			   rq->batch ? lower_32_bits(rq->batch->node.start) : ~0u);

While you are here, you might want to add the new rq->infix to the mix.

Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>

> +
> +		size = rq->tail - rq->head;
> +		if (rq->tail < rq->head)
> +			size += rq->ring->size;
> +
> +		ring = kmalloc(size, GFP_ATOMIC);
> +		if (ring) {
> +			const void *vaddr = rq->ring->vaddr;
> +			unsigned int head = rq->head;
> +			unsigned int len = 0;
> +
> +			if (rq->tail < head) {
> +				len = rq->ring->size - head;
> +				memcpy(ring, vaddr + head, len);
> +				head = 0;
> +			}
> +			memcpy(ring + len, vaddr + head, size - len);
> +
> +			hexdump(m, ring, size);
> +			kfree(ring);
> +		}
>  	}
>  
>  	rcu_read_unlock();
> -- 
> 2.17.1
>
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