Re: [PATCH 03/10] PCI: AMD SATA IDE mode quirk

[Matthew Wilcox <matthew@wil.cx>]

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) {

> > 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.

-- 
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