linux-kernel - Re: [PATCH v1 1/1] fpga: dfl: pci: Use pci_find_vsec

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Date: Wed, 3 Apr 2024 14:01:25 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Tom Rix <trix@...hat.com>
Cc: Moritz Fischer <mdf@...nel.org>,
	Matthew Gerlach <matthew.gerlach@...ux.intel.com>,
	linux-fpga@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Wu Hao <hao.wu@...el.com>, Xu Yilun <yilun.xu@...el.com>
Subject: Re: [PATCH v1 1/1] fpga: dfl: pci: Use pci_find_vsec_capability()
 when looking for DFL

On Wed, Nov 10, 2021 at 06:59:25PM +0200, Andy Shevchenko wrote:
> On Wed, Nov 10, 2021 at 2:28 PM Tom Rix <trix@...hat.com> wrote:
> > On 11/10/21 12:24 AM, Andy Shevchenko wrote:
> > > On Tue, Nov 09, 2021 at 10:27:58AM -0800, Tom Rix wrote:
> > >> On 11/9/21 10:05 AM, Andy Shevchenko wrote:
> > >>> On Tue, Nov 09, 2021 at 07:55:43AM -0800, Tom Rix wrote:
> > >>>> On 11/9/21 7:41 AM, Andy Shevchenko wrote:

..

> > >>>>> + voff = pci_find_vsec_capability(dev, PCI_VENDOR_ID_INTEL, PCI_VSEC_ID_INTEL_DFLS);
> > >>>> This may be a weakness in the origin code, but intel isn't the exclusive
> > >>>> user of DFL.
> > >>> This does not change the original code. If you think so, this can be extended
> > >>> later on.
> > >> I would rather see this fixed now or explained why this isn't a problem.
> > > This is out of scope of this change in a few ways:
> > >   - we don't do 2+ things in one patch
> > >   - the change doesn't change behaviour
> > >   - the change is a simple cleanup
> > >   - another vendor may well have quite different VSEC ID for DFL
> > >
> > > If you think that it should be needed, one can come up with it later on.
> >
> > Fixing a problem is more useful than a cleanup. The fix should come first.
> 
> What do you mean by that? The original code never worked with what you
> are suggesting. There is nothing to fix in terms of "fix". What you
> are proposing is a feature. And as we know the features are going into
> the kernel in a natural order, means fixes - priority 1, cleanups /
> refactoring as prerequisites to the feature enabling - priority 2,
> feature - priority 3, other cleanups and code improvements - priority
> 4.
> 
> That said, the proposed change definitely falls into category 2. It
> makes the proposed feature to be easily realized.
> 
> Also, do not forget that vendor specific stuff is _by definition_
> vendor specific, and the proposed feature is doubtful until you prove
> there is another vendor-id pair.

Interestingly that you included
8607d9c1bd57 ("fpga: dfl-pci: Use pci_find_vsec_capability() to simplify the code")
without even letting me know...

-- 
With Best Regards,
Andy Shevchenko