linux-kernel - Re: [Intel-gfx] [PATCH v2 12/25] i915: switch from acpi_os

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Message-ID: <20150727075050.GK16722@phenom.ffwll.local>
Date:	Mon, 27 Jul 2015 09:50:50 +0200
From:	Daniel Vetter <daniel@...ll.ch>
To:	Dan Williams <dan.j.williams@...el.com>
Cc:	tglx@...utronix.de, mingo@...nel.org, hpa@...or.com,
	linux-arch@...r.kernel.org, toshi.kani@...com,
	linux-nvdimm@...ts.01.org, David Airlie <airlied@...ux.ie>,
	intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	Daniel Vetter <daniel.vetter@...el.com>,
	rmk+kernel@....linux.org.uk, hch@....de,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [Intel-gfx] [PATCH v2 12/25] i915: switch from acpi_os_ioremap
 to ioremap

On Fri, Jul 24, 2015 at 10:39:04PM -0400, Dan Williams wrote:
> acpi_os_ioremap uses cached mappings, however it appears that i915
> wants to read dynamic platform state.  Switch to ioremap() to prevent it
> reading stale state from cache.
> 
> Cc: Daniel Vetter <daniel.vetter@...el.com>
> Cc: Jani Nikula <jani.nikula@...ux.intel.com>
> Cc: intel-gfx@...ts.freedesktop.org
> Cc: David Airlie <airlied@...ux.ie>
> Cc: dri-devel@...ts.freedesktop.org
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
>  drivers/gpu/drm/i915/intel_opregion.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_opregion.c b/drivers/gpu/drm/i915/intel_opregion.c
> index 481337436f72..16ba7c67410d 100644
> --- a/drivers/gpu/drm/i915/intel_opregion.c
> +++ b/drivers/gpu/drm/i915/intel_opregion.c
> @@ -863,7 +863,7 @@ int intel_opregion_setup(struct drm_device *dev)
>  	INIT_WORK(&opregion->asle_work, asle_work);
>  #endif
>  
> -	base = acpi_os_ioremap(asls, OPREGION_SIZE);
> +	base = ioremap(asls, OPREGION_SIZE);

OpRegion is cached memory shared with the firmware afaik, we probably want
a memremap here and switch away from the ioread/write stuff. We have a
similar confusion going on for the vbt parsing (which on anything but
really old machines is also just normal memory).

Same holds for gma500, which is just a copy of i915 for some special
platforms.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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