Re: [Fedora-ia64-list] [PATCH] ide controller quirk to correct bad BAR resources

From: Zhang, Yanmin <yanmin_zhang_at_linux.intel.com>
Date: 2007-02-14 14:26:18
On Tue, 2007-02-13 at 10:51 -0500, Prarit Bhargava wrote:
> 
> Zhang, Yanmin wrote:
> > If ide controllers are at legacy mode, only the 4th BAR
> > is needed, so some BIOS initiate other BAR with incorrect
> > value. ata/ata_piix calls pci_enable_device on the ide
> > controller, which will check BAR resources. If the BAR
> > resource values are incorrect, pci_enable_device will fail,
> > and ata/ata_piix couldn't attach the ide controller.
> >
> > Below patch against 2.6.20 creates a quirk to correct the
> > bad BAR resources for a special ide controller which is
> > popular on tiger-4.
> >
> >   
> 
> If I understand the use of quirks, it is to fix hardware issues that 
> cannot be resolved by bios fixes, etc..  ie) real HW problems.  At least 
> that's been my feeble understanding.  If I'm wrong on that please 
> correct me.
Correct.

Curent issue of ide controller also could be considered as ide hardware
issue. If the ide controller is at legacy mode, bar 4 is enough, but
my ide controller provides bar 5 as well as 4. If the controller
hardwires bar 5 as 0, there will be no such issue.

> 
> Putting this sort of fix in opens up the kernel to resolving many 
> vendors' bios issues within the kernel.
> 
> I do understand that this is a special case -- it is unlikely a new bios 
> will ship for this box.  The way I see it, a future user of this 
> platform will have to build kernels that use the old ide-cd/piix driver 
> and/or patch the specific OS they are using with this patch.
>From Alan's reply on linux-ide maillist, we could know another platform
PowerPC has the similiar issue. It assumes the BAR is not used if it is equal
to 0.

>From the comments of function ide_pci_enable of the old ide driver, we could
see that such issue is not rare.

Is it better to put the patch into upstream kernel?

Yanmin
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Received on Wed Feb 14 14:26:32 2007

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