linux-kernel - Re: [RFC/PATCH v2 5/8] i915: Use arch_phys_wc

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Message-ID: <20130510093605.GI12292@phenom.ffwll.local>
Date:	Fri, 10 May 2013 11:36:05 +0200
From:	Daniel Vetter <daniel@...ll.ch>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	linux-fbdev@...r.kernel.org,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Jerome Glisse <j.glisse@...il.com>,
	Alex Deucher <alexdeucher@...il.com>,
	Dave Airlie <airlied@...il.com>
Subject: Re: [RFC/PATCH v2 5/8] i915: Use arch_phys_wc_{add,del}

On Thu, May 09, 2013 at 12:46:24PM -0700, Andy Lutomirski wrote:
> i915 open-coded logic that was essentially equivalent to the new API.
> 
> Signed-off-by: Andy Lutomirski <luto@...capital.net>
> ---
> 
> Changes from v1: More cleanup
> 
>  drivers/gpu/drm/i915/i915_dma.c | 44 ++++++-----------------------------------
>  1 file changed, 6 insertions(+), 38 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 4fa6beb..cfdfb45 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -42,7 +42,6 @@
>  #include <linux/vga_switcheroo.h>
>  #include <linux/slab.h>
>  #include <acpi/video.h>
> -#include <asm/pat.h>
>  
>  #define LP_RING(d) (&((struct drm_i915_private *)(d))->ring[RCS])
>  
> @@ -1393,29 +1392,6 @@ void i915_master_destroy(struct drm_device *dev, struct drm_master *master)
>  	master->driver_priv = NULL;
>  }
>  
> -static void
> -i915_mtrr_setup(struct drm_i915_private *dev_priv, unsigned long base,
> -		unsigned long size)
> -{
> -	dev_priv->mm.gtt_mtrr = -1;
> -
> -#if defined(CONFIG_X86_PAT)
> -	if (cpu_has_pat)
> -		return;
> -#endif
> -
> -	/* Set up a WC MTRR for non-PAT systems.  This is more common than
> -	 * one would think, because the kernel disables PAT on first
> -	 * generation Core chips because WC PAT gets overridden by a UC
> -	 * MTRR if present.  Even if a UC MTRR isn't present.
> -	 */
> -	dev_priv->mm.gtt_mtrr = mtrr_add(base, size, MTRR_TYPE_WRCOMB, 1);
> -	if (dev_priv->mm.gtt_mtrr < 0) {
> -		DRM_INFO("MTRR allocation failed.  Graphics "
> -			 "performance may suffer.\n");
> -	}
> -}
> -
>  static void i915_kick_out_firmware_fb(struct drm_i915_private *dev_priv)
>  {
>  	struct apertures_struct *ap;
> @@ -1552,8 +1528,8 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
>  		goto out_rmmap;
>  	}
>  
> -	i915_mtrr_setup(dev_priv, dev_priv->gtt.mappable_base,
> -			aperture_size);
> +	dev_priv->mm.gtt_mtrr = arch_phys_wc_add(dev_priv->gtt.mappable_base,
> +						 aperture_size);
>  
>  	/* The i915 workqueue is primarily used for batched retirement of
>  	 * requests (and thus managing bo) once the task has been completed
> @@ -1656,12 +1632,8 @@ out_gem_unload:
>  	intel_teardown_mchbar(dev);
>  	destroy_workqueue(dev_priv->wq);
>  out_mtrrfree:
> -	if (dev_priv->mm.gtt_mtrr >= 0) {
> -		mtrr_del(dev_priv->mm.gtt_mtrr,
> -			 dev_priv->gtt.mappable_base,
> -			 aperture_size);
> -		dev_priv->mm.gtt_mtrr = -1;
> -	}
> +	arch_phys_wc_del(dev_priv->mm.gtt_mtrr);
> +	dev_priv->mm.gtt_mtrr = 0;

I think you can drop this gtt_mtrr = 0 asignment (and the one below) since
the driver will be unloaded anyway and no longer care. And with my
bikeshed on the first 1 patch it'd be wrong, too.
-Daniel

>  	io_mapping_free(dev_priv->gtt.mappable);
>  out_rmmap:
>  	pci_iounmap(dev->pdev, dev_priv->regs);
> @@ -1697,12 +1669,8 @@ int i915_driver_unload(struct drm_device *dev)
>  	cancel_delayed_work_sync(&dev_priv->mm.retire_work);
>  
>  	io_mapping_free(dev_priv->gtt.mappable);
> -	if (dev_priv->mm.gtt_mtrr >= 0) {
> -		mtrr_del(dev_priv->mm.gtt_mtrr,
> -			 dev_priv->gtt.mappable_base,
> -			 dev_priv->gtt.mappable_end);
> -		dev_priv->mm.gtt_mtrr = -1;
> -	}
> +	arch_phys_wc_del(dev_priv->mm.gtt_mtrr);
> +	dev_priv->mm.gtt_mtrr = 0;
>  
>  	acpi_video_unregister();
>  
> -- 
> 1.8.1.4
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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