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

From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Marek Vasut <marek.vasut@gmail.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	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 13:42:32 +0100	[thread overview]
Message-ID: <CAMuHMdWPZdD3Kat_XJ33ubiiXr4CE_zP7crqrAcbzqOB58V-PQ@mail.gmail.com> (raw)
In-Reply-To: <9b432b16-35a1-c4ec-df97-8f6f854ab8b4@gmail.com>

Hi Marek,

On Fri, Mar 22, 2019 at 1:33 PM Marek Vasut <marek.vasut@gmail.com> wrote:
> On 3/22/19 1:29 PM, Geert Uytterhoeven wrote:
> > 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?
>
> Wouldn't you also hit this on ARM32 LPAE ones ?

This is about the PCI link issue on system resume, 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