Re: [PATCH v3] PCI: rcar-gen4: Add missing PM ops

[Marek Vasut <marek.vasut@mailbox.org>]

Hello Den-san,

On 9/8/26 3:05 AM, Koichiro Den wrote:
> On Mon, Sep 07, 2026 at 06:35:22PM +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.
>>
>> 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")
>> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
>> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
>> Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
>> Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
>> ---
> 
> The s2idle test with pm_test=platform now passes in EP mode on S4 Spider even
> with CONFIG_PCIE_DW_HOST=y. Thanks! Feel free to use the tag for it if it helps.
> 
> Tested-by: Koichiro Den <den@valinux.co.jp>
Thank you for your test. I would like to ask -- is the EP side of PCIe 
link behaving correctly during suspend/resume cycle on your S4 setup ? 
Does the EP require any special handling during suspend/resume ?

Thank you for your help !

-- 
Best regards,
Marek Vasut