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Message-ID: <20080225073100.GE26674@colo.lackof.org>
Date: Mon, 25 Feb 2008 00:31:00 -0700
From: Grant Grundler <grundler@...isc-linux.org>
To: "Cai, Crane" <Crane.Cai@....com>
Cc: Matthew Wilcox <matthew@....cx>,
Greg Kroah-Hartman <gregkh@...e.de>,
linux-pci@...ey.karlin.mff.cuni.cz, linux-kernel@...r.kernel.org,
Linus Torvalds <torvalds@...l.org>,
Andrew Morton <akpm@...l.org>
Subject: Re: [PATCH 03/10] PCI: AMD SATA IDE mode quirk
On Mon, Feb 25, 2008 at 09:43:59AM +0800, Cai, Crane wrote:
> > On Fri, Feb 22, 2008 at 01:49:20PM +0800, Cai, Crane wrote:
> > > > On Thu, Feb 21, 2008 at 03:47:33PM -0800, Greg
> > Kroah-Hartman wrote:
> > > > > +static void __devinit quirk_amd_ide_mode(struct pci_dev *pdev)
> > > > > {
> > > > > - /* set sb600 sata to ahci mode */
> > > > > - if ((pdev->class >> 8) == PCI_CLASS_STORAGE_IDE) {
> > > > > - u8 tmp;
> > > > > + /* set sb600/sb700/sb800 sata to ahci mode */
> > > > > + u8 tmp;
> > > > >
> > > > > + pci_read_config_byte(pdev, PCI_CLASS_DEVICE, &tmp);
> > > > > + if (tmp == 0x01) {
> > > > > pci_read_config_byte(pdev, 0x40, &tmp);
> > > >
> > > > This seems like a dis-improvement. Why are we reading a
> > config byte
> > > > for something we already have in the pci_dev?
> > > > Why are we now checking against 0x01 instead of a
> > symbolic constant?
> > > > Why are we no longer checking that this is PCI_BASE_CLASS_STORAGE?
> > > It is a quirk. In pci_ids.h did have PCI_CLASS_STORAGE_IDE and
> > > PCI_BASE_CLASS_STORAGE, these can not represent the right
> > situation we
> > > want to check. 0x01 represents PCI_CLASS_STORAGE_IDE last 2
> > bit. Also
> > > because it is a quirk, I do not think we need to change
> > pci_ids.h. So
> > > 0x01 used.
> >
> > You haven't explained what is wrong with the original code:
> >
> > if ((pdev->class >> 8) == PCI_CLASS_STORAGE_IDE) {
> >
>
> When resume, this pdev->class is quirked, however BIOS has
> modified pci configuration too. Inconsistance occurs.
Can you update pdev->class from the quirk?
It would be consistent then.
That would leave the code as-is except it's re-reading the field
from config space.
hth,
grant
> > > > Nothing in the changelog entry suggests why we now need
> > FIXUP_RESUME
> > > > entries when we didn't before.
> > > >
> > > PCI configuration space will be changed by BIOS and then in
> > pci init
> > > and restore. So resume also needed.
> >
> > That information needed to be in the changelog.
>
> This info, is a normal info. If maintainer need us to added in source code. I preferred too.
> > --
> > Intel are signing my paycheques ... these opinions are still
> > mine "Bill, look, we understand that you're interested in
> > selling us this operating system, but compare it to ours. We
> > can't possibly take such a retrograde step."
> >
> >
> >
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