Re: [PATCH v3 18/18] PCI: j721e: add suspend and resume support

Théo Lebrun
2024-02-16T11:09:20Z

Hello,

On Fri Feb 16, 2024 at 11:48 AM CET, Siddharth Vadapalli wrote:
> On 24/02/15 04:18PM, Thomas Richard wrote:
> > From: Théo Lebrun <theo.lebrun@bootlin.com>
> >
> > Add suspend and resume support. Only the rc mode is supported.
> >
> > During the suspend stage PERST# is asserted, then deasserted during the
> > resume stage.
>
> Wouldn't this imply that the Endpoint device will be reset and therefore
> lose context? Or is it expected that the driver corresponding to the
> Endpoint Function in Linux will restore the state on resume, post reset?

This does imply exactly that. Endpoint driver must be able to restore
context anyway, as system-wide suspend could mean lost power to PCI RC
controller (eg suspend-to-RAM) or PCI rails (dependent on hardware).

Thanks,

--
Théo Lebrun, Bootlin
Embedded Linux and Kernel engineering