Re: [BUG?] ata disk running maximum at DMA33 with 2.6.20 and new pata driver, NV CK804 ide controller.

[Robert Hancock <hancockr@shaw.ca>]

Alan wrote:
> On Wed, 7 Feb 2007 01:19:36 +0100
> Luigi Genoni <genoni@sns.it> wrote:
> 
>> Hi,
>> since upgrading to kernel 2.6.20 my pata disk, using new pata driver, is
>> initialized maximum  in DMA33 mode (and obviously performances drop 
>> consequently), as you can see from:
> 
> Interesting.
> 
>> Willing to test any patch.
> 
> Firstly can you see if its consistently the case that booting 2.6.20
> gives UDMA33 and 2.6.19 UDMA100 over a few reboots. If it is please drop
> the 2.6.19 drivers/ata/pamd_amd into 2.6.20 and try that.

As an aside to this sort of problem, shouldn't we print some kind of 
loud message in dmesg when we force a high-UDMA-capable device down to 
UDMA33 due to a 40-wire cable detection? In the case where it truly is a 
40-wire cable the user may want to know that and replace the cable, if 
it isn't it gives more of a hint of why the drive isn't running at full 
speed..

-- 
Robert Hancock      Saskatoon, SK, Canada
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