Re: [Intel-gfx] [PATCH] [v2] drm/i915: Fix context sizes on HSW

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Mon, 24 Jun 2013 15:17:09 -0700
Ben Widawsky <ben@bwidawsk.net> wrote:

> With updates to the spec, we can actually see the context layout, and
> how many dwords are allocated. That table suggests we need 70720 bytes
> per HW context. Rounded up, this is 18 pages. Looking at what lives
> after the current 4 pages we use, I can't see too much important (mostly
> it's d3d related), but there are a couple of things which look scary. I
> am hopeful this can explain some of our odd HSW failures.
> 
> v2: Make the context only 17 pages. The power context space isn't used
> ever, and execlists aren't used in our driver, making the actual total
> 66944 bytes.
> 
> Reported-by: "Azad, Vinit" <vinit.azad@intel.com>
> Cc: stable@vger.kernel.org
> Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
> ---
>  drivers/gpu/drm/i915/i915_gem_context.c | 2 +-
>  drivers/gpu/drm/i915/i915_reg.h         | 9 +--------
>  2 files changed, 2 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> index ff47145..51b7a21 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -113,7 +113,7 @@ static int get_context_size(struct drm_device *dev)
>  	case 7:
>  		reg = I915_READ(GEN7_CXT_SIZE);
>  		if (IS_HASWELL(dev))
> -			ret = HSW_CXT_TOTAL_SIZE(reg) * 64;
> +			ret = HSW_CXT_TOTAL_SIZE;
>  		else
>  			ret = GEN7_CXT_TOTAL_SIZE(reg) * 64;
>  		break;
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 2102ff3..f061c67 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -1718,14 +1718,7 @@
>  					 GEN7_CXT_EXTENDED_SIZE(ctx_reg) + \
>  					 GEN7_CXT_GT1_SIZE(ctx_reg) + \
>  					 GEN7_CXT_VFSTATE_SIZE(ctx_reg))
> -#define HSW_CXT_POWER_SIZE(ctx_reg)	((ctx_reg >> 26) & 0x3f)
> -#define HSW_CXT_RING_SIZE(ctx_reg)	((ctx_reg >> 23) & 0x7)
> -#define HSW_CXT_RENDER_SIZE(ctx_reg)	((ctx_reg >> 15) & 0xff)
> -#define HSW_CXT_TOTAL_SIZE(ctx_reg)	(HSW_CXT_POWER_SIZE(ctx_reg) + \
> -					 HSW_CXT_RING_SIZE(ctx_reg) + \
> -					 HSW_CXT_RENDER_SIZE(ctx_reg) + \
> -					 GEN7_CXT_VFSTATE_SIZE(ctx_reg))
> -
> +#define HSW_CXT_TOTAL_SIZE		(17 * PAGE_SIZE)
>  
>  /*
>   * Overlay regs

Yeah, we can't rely on the reg I guess, and this matches the docs
(though they don't make it easy to figure it out)...  I'd like to see a
reference to the bspec where this information is kept, but other than
that:

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>

-- 
Jesse Barnes, Intel Open Source Technology Center