Re: [PATCH 46/53] drm/i915/bdw: Display execlists info in debugfs

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, Jun 13, 2014 at 04:38:04PM +0100, oscar.mateo@intel.com wrote:
> From: Oscar Mateo <oscar.mateo@intel.com>
> 
> v2: Warn and return if LRCs are not enabled.
> 
> Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_debugfs.c | 72 +++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_lrc.c    |  6 ----
>  drivers/gpu/drm/i915/intel_lrc.h    |  7 ++++
>  3 files changed, 79 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index b09cab4..3ccdf0d 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -1753,6 +1753,77 @@ static int i915_context_status(struct seq_file *m, void *unused)
>  	return 0;
>  }
>  
> +static int i915_execlists(struct seq_file *m, void *data)
> +{
> +	struct drm_info_node *node = (struct drm_info_node *) m->private;
> +	struct drm_device *dev = node->minor->dev;
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	struct intel_engine_cs *ring;
> +	u32 status_pointer;
> +	u8 read_pointer;
> +	u8 write_pointer;
> +	u32 status;
> +	u32 ctx_id;
> +	struct list_head *cursor;
> +	struct intel_ctx_submit_request *head_req;
> +	int ring_id, i;
> +
> +	if (!intel_enable_execlists(dev)) {
> +		seq_printf(m, "Logical Ring Contexts are disabled\n");
> +		return 0;
> +	}
> +
> +	for_each_ring(ring, dev_priv, ring_id) {
> +		int count = 0;
> +
> +		seq_printf(m, "%s\n", ring->name);
> +
> +		status = I915_READ(RING_EXECLIST_STATUS(ring));
> +		ctx_id = I915_READ(RING_EXECLIST_STATUS(ring) + 4);
> +		seq_printf(m, "\tExeclist status: 0x%08X, context: %u\n",
> +				status, ctx_id);
> +
> +		status_pointer = I915_READ(RING_CONTEXT_STATUS_PTR(ring));
> +		seq_printf(m, "\tStatus pointer: 0x%08X\n", status_pointer);
> +
> +		read_pointer = ring->next_context_status_buffer;
> +		write_pointer = status_pointer & 0x07;
> +		if (read_pointer > write_pointer)
> +			write_pointer += 6;
> +		seq_printf(m, "\tRead pointer: 0x%08X, write pointer 0x%08X\n",
> +				read_pointer, write_pointer);
> +
> +		for (i = 0; i < 6; i++) {
> +			status = I915_READ(RING_CONTEXT_STATUS_BUF(ring) + 8*i);
> +			ctx_id = I915_READ(RING_CONTEXT_STATUS_BUF(ring) + 8*i + 4);
> +
> +			seq_printf(m, "\tStatus buffer %d: 0x%08X, context: %u\n",
> +					i, status, ctx_id);
> +		}
> +
> +		list_for_each(cursor, &ring->execlist_queue) {
> +			count++;
> +		}
> +		seq_printf(m, "\t%d requests in queue\n", count);
> +
> +		if (count > 0) {
> +			struct drm_i915_gem_object *ctx_obj;
> +
> +			head_req = list_first_entry(&ring->execlist_queue,
> +					struct intel_ctx_submit_request, execlist_link);
> +
> +			ctx_obj = head_req->ctx->engine[ring_id].obj;
> +			seq_printf(m, "\tHead request id: %u\n",
> +					intel_execlists_ctx_id(ctx_obj));
> +			seq_printf(m, "\tHead request tail: %u\n", head_req->tail);
> +		}
> +
> +		seq_putc(m, '\n');
> +	}
> +
> +	return 0;
> +}

debugfs files with 0 locking tend to eventually blow up. Please don't even
though there's way too much precedence. I know that means you first have
to debug the deadlock if you hit such a beast, but usually lockdep and the
other in-kernel tooling are adequate for that.
-Daniel

> +
>  static int i915_gen6_forcewake_count_info(struct seq_file *m, void *data)
>  {
>  	struct drm_info_node *node = m->private;
> @@ -3813,6 +3884,7 @@ static const struct drm_info_list i915_debugfs_list[] = {
>  	{"i915_opregion", i915_opregion, 0},
>  	{"i915_gem_framebuffer", i915_gem_framebuffer_info, 0},
>  	{"i915_context_status", i915_context_status, 0},
> +	{"i915_execlists", i915_execlists, 0},
>  	{"i915_gen6_forcewake_count", i915_gen6_forcewake_count_info, 0},
>  	{"i915_swizzle_info", i915_swizzle_info, 0},
>  	{"i915_ppgtt_info", i915_ppgtt_info, 0},
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index ea4b358..c23c0f6 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -46,12 +46,6 @@
>  
>  #define GEN8_LR_CONTEXT_ALIGN 4096
>  
> -#define RING_ELSP(ring)			((ring)->mmio_base+0x230)
> -#define RING_EXECLIST_STATUS(ring)	((ring)->mmio_base+0x234)
> -#define RING_CONTEXT_CONTROL(ring)	((ring)->mmio_base+0x244)
> -#define RING_CONTEXT_STATUS_BUF(ring)	((ring)->mmio_base+0x370)
> -#define RING_CONTEXT_STATUS_PTR(ring)	((ring)->mmio_base+0x3a0)
> -
>  #define RING_EXECLIST_QFULL		(1 << 0x2)
>  #define RING_EXECLIST1_VALID		(1 << 0x3)
>  #define RING_EXECLIST0_VALID		(1 << 0x4)
> diff --git a/drivers/gpu/drm/i915/intel_lrc.h b/drivers/gpu/drm/i915/intel_lrc.h
> index ee877aa..c318dcb 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.h
> +++ b/drivers/gpu/drm/i915/intel_lrc.h
> @@ -1,6 +1,13 @@
>  #ifndef _INTEL_LRC_H_
>  #define _INTEL_LRC_H_
>  
> +/* Execlists regs */
> +#define RING_ELSP(ring)			((ring)->mmio_base+0x230)
> +#define RING_EXECLIST_STATUS(ring)	((ring)->mmio_base+0x234)
> +#define RING_CONTEXT_CONTROL(ring)	((ring)->mmio_base+0x244)
> +#define RING_CONTEXT_STATUS_BUF(ring)	((ring)->mmio_base+0x370)
> +#define RING_CONTEXT_STATUS_PTR(ring)	((ring)->mmio_base+0x3a0)
> +
>  /* Logical Rings */
>  void intel_logical_ring_cleanup(struct intel_engine_cs *ring);
>  int intel_logical_rings_init(struct drm_device *dev);
> -- 
> 1.9.0
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch