Message-ID: <4797ECF8.9000606@garzik.org>
Date: Wed, 23 Jan 2008 20:42:16 -0500
From: Jeff Garzik <jeff@garzik.org>
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To: Robert Hancock <hancockr@shaw.ca>
CC: Kuan Luo <kluo@nvidia.com>, Tejun Heo <htejun@gmail.com>,
       Mark Lord <liml@rtr.ca>,
       IDE/ATA development list <linux-ide@vger.kernel.org>,
       Allen Martin <AMartin@nvidia.com>, Peer Chen <pchen@nvidia.com>,
       linux-kernel <linux-kernel@vger.kernel.org>,
       David Milburn <dmilburn@redhat.com>
Subject: Re: sata_nv and 2.6.24 (was Re: fixed a bug of adma in rhel4u5 with
 HDS7250SASUN500G.)
References: <4781F008.9070404@gmail.com> <4782422C.8020202@rtr.ca> <4782B73B.8080309@shaw.ca> <4782BC48.4000309@gmail.com> <4782C008.3030902@shaw.ca> <4782CB62.7040901@gmail.com> <4782CEF9.3040708@gmail.com> <4782DFFE.50301@shaw.ca> <4782E5A8.9010305@gmail.com> <4782E63E.1000606@gmail.com> <4782E78F.9050205@shaw.ca> <4782E912.1050204@gmail.com> <4783493A.7070800@gmail.com> <47838B57.8020407@shaw.ca> <47842A54.2060107@gmail.com> <47842ABA.2060605@gmail.com> <47844471.4070705@shaw.ca> <47845708.6060900@gmail.com> <478567D8.10601@shaw.ca> <15F501D1A78BD343BE8F4D8DB854566B1BFE2ABF@hkemmail01.nvidia.com> <478812C9.1000901@shaw.ca> <15F501D1A78BD343BE8F4D8DB854566B1BFE2AC0@hkemmail01.nvidia.com> <478AF10D.5080805@shaw.ca> <479709BE.2090707@garzik.org> <479752D7.4020206@shaw.ca>
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Robert Hancock wrote:
> Jeff Garzik wrote:
>> Ping...  sata_nv status is still a bit open for 2.6.24, and I would 
>> like to move us forward a bit.
>>
>> * Kuan's patch...  it has been confirmed (and is needed), correct?  
>> can someone work up a good patch for 2.6.24?  The only one I ever 
>> received was badly word-wrapped, and at the time, Robert seemed 
>> uncertain of it, so I waited.
> 
> I can get you one later today hopefully.
> 
>>
>> * ADMA ATAPI 4GB issues...  playing tricks with the ordering of 
>> allocations and DMA masks is just way too fragile.  We just cannot 
>> guarantee that all allocators work that way.  The obvious solution to 
>> me seems to be hardcoding the consistent DMA mask to 32-bit, but using 
>> 64-bit for regular dma mask if-and-only-if ADMA is enabled.
> 
> That's not enough to fix the problem since there's issues with actual 
> transfer data being allocated above 4GB as well, not just the consistent 
>  allocations (it appears that blk_queue_bounce_limit setting to 32-bit 
> doesn't prevent this on x86_64). Either we play some funky games with 
> changing the DMA mask of the entire device to 32-bit if either port is 
> in ATAPI mode (which blew up when I tried it) or we add the ability to 
> set the DMA mask independently on each port (like by setting the mask on 
> the SCSI device and using that for DMA mapping instead) which requires 
> core changes.

Its all funky games that no other driver is doing...  There is one 
guaranteed to work scenario -- set all masks and bounce limits etc. to 
32-bit.  There is also one highly-likely-to-work scenario, disabling 
ADMA by default.


>> * it sure seems like there are other open sata_nv ADMA issues -- can 
>> we hard-confirm or deny this?  bugzilla wasn't very helpful for me.  
>> It doesn't seem like we can disable ADMA (to solve those issues) and 
>> get enough test time in (which is what I said a week (or more?) ago 
>> too...)
> 
> The NCQ/non-NCQ command switching issue is still hitting some people 
> (last I heard Kuan was looking into this), also there's a hotplug issue 
> that Tejun reported..

The former implies we need to disable swncq for 2.6.24, if it's not 
stable yet.

	Jeff


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