[PATCH V3 RFC 8/9] usb: dwc2: Implement recovery after PM domain off

[Doug Anderson]

Hi,

On Wed, Aug 21, 2024 at 2:41 PM Stefan Wahren <wahrenst at gmx.net> wrote:
>
> According to the dt-bindings there are some platforms, which have a
> dedicated USB power domain for DWC2 IP core supply. If the power domain
> is switched off during system suspend then all USB register will lose
> their settings.
>
> Use GUSBCFG_TOUTCAL as a canary to detect that the power domain has
> been powered off during suspend. Since the GOTGCTL_CURMODE_HOST doesn't
> match on all platform with the current mode, additionally backup
> GINTSTS. This works reliable to decide which registers should be
> restored.
>
> Signed-off-by: Stefan Wahren <wahrenst at gmx.net>
> ---
>  drivers/usb/dwc2/core.c     |  1 +
>  drivers/usb/dwc2/core.h     |  2 ++
>  drivers/usb/dwc2/platform.c | 38 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 41 insertions(+)
> +static int dwc2_restore_critical_registers(struct dwc2_hsotg *hsotg)
> +{
> +       struct dwc2_gregs_backup *gr;
> +
> +       gr = &hsotg->gr_backup;
> +
> +       if (!gr->valid) {
> +               dev_err(hsotg->dev, "%s: no registers to restore\n",
> +                       __func__);

nit: IMO "__func__" should not be in dev_err() messages. The message
plus the device should be enough. If __func__ should have been in
dev_err() messages then the Linux kernel would have automatically put
it there.

Aside from that, this looks reasonable to me and discussed previously.

Reviewed-by: Douglas Anderson <dianders at chromium.org>