Re: [PATCHv2] pci: allow user specifiy a reset poll timeout

[Keith Busch <kbusch@kernel.org>]

On Wed, Jun 11, 2025 at 09:58:59PM +0530, Manivannan Sadhasivam wrote:
> On Mon, Apr 14, 2025 at 06:11:44PM -0600, Keith Busch wrote:
> > On Tue, Feb 18, 2025 at 08:54:44AM -0800, Keith Busch wrote:
> > > From: Keith Busch <kbusch@kernel.org>
> > > 
> > > The spec does not provide any upper limit to how long a device may
> > > return Request Retry Status. It just says "Some devices require a
> > > lengthy self-initialization sequence to complete". The kernel
> > > arbitrarily chose 60 seconds since that really ought to be enough. But
> > > there are devices where this turns out not to be enough.
> > > 
> > > Since any timeout choice would be arbitrary, and 60 seconds is generally
> > > more than enough for the majority of hardware, let's make this a
> > > parameter so an admin can adjust it specifically to their needs if the
> > > default timeout isn't appropriate.
> > 
> > This patch is trying to address timings that have no spec defined
> > behavior, so making it user tunable sounds just more reasonable than a
> > kernel define. If we're not considering upstream options to make this
> > tunable, I think we have no choice but to continue with bespoke
> > out-of-tree solutions.
> 
> Do we know the list of devices exhibiting this pattern? And does the time limit
> is deterministic? I'm just trying to see if it is possible to add quirks for
> those devices.

No. I'm dealing with new devices being actively developed, with new ones
coming out every year, so a quirk list would just be never ending
maintenance pain point. The fact I can't point them to off-the-shelf
kernels to test with has been frustrating for everyone. If we just had a
user defined option instead of forcing the kernel's arbitrary choice,
then the problem is solved once and forever.