linux-kernel - Re: [PATCH] pci: don't enable too much HT MSI mapping -v5 -resend

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Date:	Sat, 28 Mar 2009 13:18:19 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Prakash Punnoor <prakash@...noor.de>
CC:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Matthew Wilcox <matthew@....cx>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Robert Hancock <hancockrwd@...il.com>, david@...g.hm,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-pci@...r.kernel.org
Subject: Re: [PATCH] pci: don't enable too much HT MSI mapping -v5 -resend

Prakash Punnoor wrote:
> On Samstag 28 März 2009 13:34:44 Prakash Punnoor wrote:
>> On Freitag 27 März 2009 00:10:01 Jesse Barnes wrote:
>>> On Fri, 20 Mar 2009 19:29:41 -0700
>>>
>>> Yinghai Lu <yinghai@...nel.org> wrote:
>>>> Impact: fix bug
>>>>
>>>> Prakash reported that his c51-mcp51 system ondie sound card doesn't
>>>> work MSI but if he hack out the HT-MSI on mcp51, the MSI will work
>>>> well with sound card.
>>>>
>>>> this patch rework the nv_msi_ht_cap_quirk()
>>>> and will only try to avoid to enable ht_msi on device following that
>>>> root dev, and don't touch that root dev
>>>>
>>>> v3: will enable c51...
>>>> v4: will enable c51 kind of without leaf too.
>>>> v5: update to mainline
>>>>
>>>> Reported-by: Prakash Punnoor <prakash@...noor.de>
>>>> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
>>> Applied, thanks.  Prakash if you get a chance can you try testing my
>>> linux-next branch (or just linux-next in general tomorrow) to make sure
>>> this is still ok for you?
>>>
>>> Thanks,
>> Finally I am able to test the linux-next branch of pci tree after Jesse
>> gave some help with git.(Is it correct that the kernel calls itself
>> 2.6.28-rc8? I looked into quirks.c and it seems to be correctly patched.)
>> Unfortunately it doesn't seem to work for me (and I am wondering why as the
>> old v4 version seemed to work ontop of one of the 2.6.29-rc versions):
>>
>> dmesg|grep HT
>> pci 0000:00:00.0: Found disabled HT MSI Mapping
>> pci 0000:00:03.0: Enabling HT MSI Mapping
>> pci 0000:00:09.0: Found disabled HT MSI Mapping
>> pci 0000:00:0e.0: Enabling HT MSI Mapping
>> pci 0000:00:09.0: Found disabled HT MSI Mapping
>> pci 0000:00:0f.0: Enabling HT MSI Mapping
>> pci 0000:00:09.0: Found disabled HT MSI Mapping
>> pci 0000:00:10.0: Enabling HT MSI Mapping
>> pci 0000:00:09.0: Found disabled HT MSI Mapping
>> pci 0000:00:10.1: Enabling HT MSI Mapping
>>
>> Device 09.0 doesn't get enabled (good) but 00.0 also not (bad). Then my
>> Intel HDA cannot use MSI.
> 
> I sprinkeld a few debugging messages around in the code and looking at that
> I don't see how the code can enable NMSI for device 00.0, but not for 09.0:
> 
> Both will exit here:
> 
> if (host_bridge == dev && host_bridge_with_leaf(host_bridge))
> 
> in nv_ht_enable_msi_mapping, so it seems host_bridge_with_leaf returns true 
> for both. I think because my hw configuration changed a bit (inserted one
> PCIe card) comparing to last time I tested old v4 version, this doesn't work
> anymore - so the leaf check alone is not realiable, I guess. For me adding
> something like this, makes it work: (I hope the description makes sense, as
> I am just refering to the function names and trying to guess its meanings.)
> 
> Patch is against linux-next branch of pci tree.
> 
> [patch] pci: enable MSI on host bridge without checking for leaves
> 
> On C51 the host bridge needs to be enabled, but the MCP51 host bridge not.
> So don't check for leaves on the main host bridge.
> 
> Signed-off-by: Prakash Punnoor <prakash@...noor.de>
> 
> --- drivers/pci/quirks.c.old    2009-03-28 14:06:07.249250095 +0100
> +++ drivers/pci/quirks.c        2009-03-28 14:22:35.027510230 +0100
> @@ -2292,8 +2292,10 @@ static void __devinit __nv_msi_ht_cap_qu
>         if (pos != 0) {
>                 /* Host bridge is to HT */
>                 if (found == 1) {
> -                       /* it is not enabled, try to enable it */
> -                       if (all)
> +                       /* it is not enabled, try to enable it;
> +                        * don't check for leaves on host bridge
> +                        */
> +                       if (all || host_bridge->devfn == dev->devfn)
>                                 ht_enable_msi_mapping(dev);
>                         else
>                                 nv_ht_enable_msi_mapping(dev);
> 

seems it is not right, it may enable your 09.0 again.

YH
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