Re: [PATCH v5] PCI: rcar-gen4: Add missing PM ops

[Geert Uytterhoeven]

Hi Mani,

On Sat, 17 Oct 2026 at 07:18, Manivannan Sadhasivam <mani@xxxxxxxxxx> wrote:
> On Sun, Oct 04, 2026 at 03:18:13AM +0200, Marek Vasut wrote:
> > The R-Car Gen4 PCIe controller is part of a power domain. On R-Car S4
> > and V4H, this is an always-on power domain which is not shut down in
> > suspend. On R-Car V4M, this is a dedicated A2PCIPHY power domain,
> > which is shut down during suspend, and the controller loses state,
> > which prevents the PCIe from working after resume.
> >
> > Fix this by adding generic suspend/resume noirq ops for the controller,
> > which tear the link down on suspend, and restart it on resume. Use the
> > same PM ops on all of R-Car Gen4 to gracefully suspend and resume the
> > PCIe link on V4H and S4 too.
> >
>
> In the future, if any one of your Endpoint didn't allow the link to enter L2,
> then you need to set the 'suspend_poweroff' flag for V4M or other SoCs which
> pulls the plug during suspend:
> https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/commit/?id=f845c1e2d2d4506802244ea2a378ae7b04e90bfe
>
> > Test case which demonstrates the problem on R-Car V4M:
> > "
> > $ hexdump -vC /sys/bus/pci/devices/0000:00:00.0/config > /tmp/pre
> > $ echo s2idle > /sys/power/mem_sleep
> > $ echo platform > /sys/power/pm_test
> > $ echo mem > /sys/power/state
> > $ hexdump -vC /sys/bus/pci/devices/0000:00:00.0/config > /tmp/post
> > $ diff -Naru /tmp/pre /tmp/post
> > ...
> > -00000000  12 19 32 00 07 05 10 00  00 00 04 06 00 00 01 00
> > +00000000  12 19 32 00 07 05 10 00  00 00 00 ff 00 00 80 00
> >                                           ^^^^^
> >                                     Class 0604->00ff
> > "
> >
> > Fixes: 0d0c551011df ("PCI: rcar-gen4: Add R-Car Gen4 PCIe controller support for host mode")
>
> Note that I changed this fixes tag to below while applying:
> Fixes: 0270dbe4f891 ("arm64: dts: renesas: r8a779h0: Add PCIe Host and Endpoint nodes")
>
> to reflect the fact that the V4M support is what caused the issue, not the
> initial driver support.

I beg to disagree: the bug is in the driver, but it was exposed by
the R-Car V4M DTS addition.

To make life easier for the backporting team, I think it is best to
list both Fixes tags.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

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