Re: [PATCH V4] PCI: handle CRS returned by device after FLR
From: Keith Busch
Date: Thu Jul 13 2017 - 13:18:35 EST
On Thu, Jul 13, 2017 at 12:42:44PM -0400, Sinan Kaya wrote:
> On 7/13/2017 12:29 PM, Keith Busch wrote:
> > That wording is just confusing. It looks to me the 1 second polling is
> > to be used following a reset if CRS is not implemented.
> > https://pcisig.com/sites/default/files/specification_documents/ECN_RN_29_Aug_2013.pdf
> > "
> > Through the mechanisms defined by this ECR, we can avoid the long,
> > architected, fixed delays following various forms of reset before
> > software is permitted to perform its first Configuration Request. These
> > delays are very large:
> > 1 second if Configuration Retry Status (CRS) is not used
> > "
> > It goes on to say CRS is usually much lower, but doesn't specify an
> > upper bound either.
> I see, we got caught on spec language where we don't know what 'its' is.
Well, I don't know for certain if your original interpretation is
incorrect. Just saying the CRS intention doesn't explicitly stand out to me.
On a side note, I'll also see if I can get clarification on what
expectations the hardware people have for this particular product. Your
observation seems a little high to me, but I don't know if that's
outside the product's limits.