Re: [PATCH V2] PCI: rcar: Add the initialization of PCIe link in resume_noirq

From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Marek Vasut <marek.vasut@gmail.com>
Cc: linux-pci <linux-pci@vger.kernel.org>,
	Kazufumi Ikeda <kaz-ikeda@xc.jp.nec.com>,
	Gaku Inami <gaku.inami.xw@bp.renesas.com>,
	Marek Vasut <marek.vasut+renesas@gmail.com>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Phil Edworthy <phil.edworthy@renesas.com>,
	Simon Horman <horms+renesas@verge.net.au>,
	Wolfram Sang <wsa@the-dreams.de>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>
Subject: Re: [PATCH V2] PCI: rcar: Add the initialization of PCIe link in resume_noirq
Date: Fri, 22 Mar 2019 13:29:33 +0100	[thread overview]
Message-ID: <CAMuHMdVt9S8ECq=FFHHLRDF4ozQc5E-kEHLZsCZaWTTi2TeC=g@mail.gmail.com> (raw)
In-Reply-To: <20190322121822.GA26257@e107981-ln.cambridge.arm.com>

Hi Lorenzo, Marek,

On Fri, Mar 22, 2019 at 1:18 PM Lorenzo Pieralisi
<lorenzo.pieralisi@arm.com> wrote:
> On Fri, Mar 22, 2019 at 01:09:13PM +0100, Marek Vasut wrote:
> > On 3/22/19 12:31 PM, Lorenzo Pieralisi wrote:
> > > On Sun, Feb 17, 2019 at 02:24:41PM +0100, marek.vasut@gmail.com wrote:
> > >> From: Kazufumi Ikeda <kaz-ikeda@xc.jp.nec.com>
> > >>
> > >> Reestablish the PCIe link very early in the resume process in case it
> > >> went down to prevent PCI accesses from hanging the bus. Such accesses
> > >> can happen early in the PCI resume process, in the resume_noirq, thus
> > >> the link must be reestablished in the resume_noirq callback of the
> > >> driver.
> > >
> > > This looks like a fix (most likely fixing initial S2R support, please
> > > help me chase the commit ID), should we consider it for stable kernels ?
> > >
> > > Without it I understand S2R is actually broken on platforms with this
> > > host bridge.
> > I don't think this ever worked, so it's hard to find a Fixes: commit for
> > this.
>
> If we want to send it to stable kernels we have to select which versions
> we are covering. I think the only options for a Fixes: tag are either
> the initial S2R support commit for the platforms this driver runs on
> or the initial driver commit that harks back to v3.16 AFAICS.

This only started to become an issue when support for arm64 platforms
was added, where PSCI may power down the SoC, right?

Hence:
Fixes: e015f88c368da1e6 ("PCI: rcar: Add support for R-Car H3 to pcie-rcar")

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds