From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Vaibhav Gupta <vaibhavgupta40@gmail.com>,
linux-kernel-mentees@lists.linuxfoundation.org,
Shuah Khan <skhan@linuxfoundation.org>,
bjorn@helgaas.com, andy@kernel.org,
Linus Walleij <linus.walleij@linaro.org>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-pci@vger.kernel.org
Subject: Re: [Linux-kernel-mentees] [PATCH v1] gpio: ml: ioh: Convert to dev_pm_ops
Date: Mon, 12 Jul 2021 14:48:12 +0300 [thread overview]
Message-ID: <YOwr/GMIExCoNjeZ@smile.fi.intel.com> (raw)
In-Reply-To: <20210708214706.GA1059661@bjorn-Precision-5520>
On Thu, Jul 08, 2021 at 04:47:06PM -0500, Bjorn Helgaas wrote:
> On Thu, Apr 02, 2020 at 11:23:27PM +0300, Andy Shevchenko wrote:
> > On Thu, Apr 2, 2020 at 11:16 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
> > > On Thu, Apr 02, 2020 at 09:33:46PM +0300, Andy Shevchenko wrote:
> > > > On Thu, Apr 2, 2020 at 6:52 PM Vaibhav Gupta <vaibhavgupta40@gmail.com> wrote:
> > > > >
> > > > > Convert the legacy callback .suspend() and .resume()
> > > > > to the generic ones.
> > > >
> > > > Thank you for the patch.
> > > >
> > > > Rather then doing this I think the best approach is to unify gpio-pch
> > > > and gpio-ml-ioh together.
> > > > Under umbrella of the task, the clean ups like above are highly
> > > > appreciated.
> > >
> > > I'd be all in favor of that, but what Vaibhav is working toward is
> > > eliminating use of legacy PM in PCI drivers. I think unifying drivers
> > > is really out of scope for that project.
> > >
> > > If you'd rather leave gpio-ml-ioh.c alone for now, I suggest that
> > > Vaibhav move on to other PCI drivers that use legacy PM. If we
> > > convert all the others away from legacy PM and gpio-ml-ioh.c is the
> > > only one remaining, then I guess we can revisit this :)
> >
> > Then skip this driver for good.
> >
> > > Or, maybe converting gpio-ml-ioh.c now, along the lines of
> > > 226e6b866d74 ("gpio: pch: Convert to dev_pm_ops"), would be one small
> > > step towards the eventual unification, by making gpio-pch and
> > > gpio-ml-ioh a little more similar.
> >
> > I think it will delay the real work here (very old code motivates
> > better to get rid of it then semi-fixed one).
>
> With respect, I think it is unreasonable to use the fact that
> gpio-ml-ioh and gpio-pch should be unified to hold up the conversion
> of gpio-ml-ioh to generic power management.
>
> I do not want to skip gpio-ml-ioh for good, because it is one of the
> few remaining drivers that use the legacy PCI PM interfaces. We are
> very close to being able to remove a significant amount of ugly code
> from the PCI core.
Makes sense (1).
> gpio-ml-ioh and gpio-pch do look quite similar, and no doubt it would
> be great to unify them. But without datasheets or hardware to test,
Datasheets are publicly available (at least one may google and find some
information about those PCH chips). I have in possession the hardware for
gpio-pch. I can easily test that part at least.
> that's not a trivial task, and I don't think that burden should fall
> on anyone who wants to make any improvements to these drivers.
> Another alternative would be to remove legacy PCI PM usage
> (ioh_gpio_suspend() and ioh_gpio_resume()) from gpio-ml-ioh. That
> would mean gpio-ml-ioh wouldn't support power management at all, which
> isn't a good thing, but maybe it would be even more motivation to
> unify it with gpio-pch (which has already been converted by
> 226e6b866d74 ("gpio: pch: Convert to dev_pm_ops"))?
With regard to (1) probably we may exceptionally accept the fix to gpio-ml-ioh,
but I really prefer to do the much more _useful_ job on it by unifying the two.
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2021-07-12 11:48 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAHp75Vfpj+ENMe9u-SMKfvCsyFtOucUT9bD3qfWX+QjccZ9ZyQ@mail.gmail.com>
2021-07-08 21:47 ` [Linux-kernel-mentees] [PATCH v1] gpio: ml: ioh: Convert to dev_pm_ops Bjorn Helgaas
2021-07-12 11:48 ` Andy Shevchenko [this message]
2021-07-12 22:36 ` Bjorn Helgaas
2021-07-12 23:07 ` Andy Shevchenko
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