From mboxrd@z Thu Jan  1 00:00:00 1970
From: Daniel Vetter <daniel@ffwll.ch>
Subject: Re: [Intel-gfx] [RFC][PATCH] gpu:drm:i915:intel_detect_pch: back to
 check devfn instead of check class type
Date: Fri, 11 Jul 2014 08:29:56 +0200
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To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>, "intel-gfx@lists.freedesktop.org" <intel-gfx@lists.freedesktop.org>, "Kay,
 Allen M" <allen.m.kay@intel.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, "Chen,
 Tiejun" <tiejun.chen@intel.com>, Paolo Bonzini <pbonzini@redhat.com>
List-Id: intel-gfx@lists.freedesktop.org

On Thu, Jul 10, 2014 at 09:08:24PM +0000, Tian, Kevin wrote:
> actually I'm curious whether it's still necessary to __detect__ PCH. Could
> we assume a 1:1 mapping between GPU and PCH, e.g. BDW already hard
> code the knowledge:
> 
>               } else if (IS_BROADWELL(dev)) {
>                       dev_priv->pch_type = PCH_LPT;
>                       dev_priv->pch_id =
>                               INTEL_PCH_LPT_LP_DEVICE_ID_TYPE;
>                       DRM_DEBUG_KMS("This is Broadwell, assuming "
>                                     "LynxPoint LP PCH\n");
> 
> Or if there is real usage on non-fixed mapping (not majority), could it be a 
> better option to have fixed mapping as a fallback instead of leaving as 
> PCH_NONE? Then even when Qemu doesn't provide a special tweaked PCH,
> the majority case just works.

I guess we can do it, at least I haven't seen any strange combinations in
the wild outside of Intel ...
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch