RE: [PATCH] pmdomain: imx: imx93-blk-ctrl: fix power up domain fail during early noriq resume

[Peng Fan]

> Subject: Re: [PATCH] pmdomain: imx: imx93-blk-ctrl: fix power up
> domain fail during early noriq resume
> 
> On Fri, 23 Aug 2024 at 11:44, Peng Fan (OSS) <peng.fan@xxxxxxxxxxx>
> wrote:
> >
> > From: Dong Aisheng <aisheng.dong@xxxxxxx>
> >
> > After disabling PXP and having no displays connected, we met the
> > following suspend/resume hang issue on MX93 EVK board.
> >
> >  Enabling non-boot CPUs ...
> >  Detected VIPT I-cache on CPU1
> >  GICv3: CPU1: found redistributor 100 region
> 0:0x0000000048060000
> >  CPU1: Booted secondary processor 0x0000000100 [0x412fd050]
> >  CPU1 is up
> >  imx93-blk-ctrl 4ac10000.system-controller: failed to power up
> domain:
> > -13  imx93-blk-ctrl 4ac10000.system-controller: failed to power up
> > domain: -13  imx93-blk-ctrl 4ac10000.system-controller: failed to
> > power up domain: -13 ...
> >
> > The issue was introduced since the commit c24efa673278
> > ("PM: runtime: Capture device status before disabling runtime PM")
> > which will also check the power.last_status must be RPM_ACTIVE
> before
> > pm_runtime_get_sync() can return 1 (means already active) even
> > pm_runtime is disabled during no_irq resume stage.
> >
> > However, the pm_runtime_set_active() we called ahead of
> > pm_runtime_get_sync() will not update power.last_status which
> probably
> > like a upstream kernel issue. But that's another issue which may
> worth
> > an extra fix.
> 
> I think this is confusing, I don't see any calls to
> pm_runtime_set_active() anywhere? Are you referring to some old
> code?

oh. I forgot to update commit message when moving this patch
to upstream

> 
> >
> > This patch refers to the solution in the exist similar imx8m blkctrl
> > driver[1] that it will power up upstream domains during blkctl
> suspend
> > first in order to make sure the power.last_status to be RPM_ACTIVE.
> > Then we can support calling pm_runtime_get_sync in noirq resume
> stage.
> >
> > After fixing, no need extra calling of pm_runtime_set_active() ahead.
> >
> > 1. drivers/pmdomain/imx/imx8m-blk-ctrl.c
> >
> > Fixes: e9aa77d413c9 ("soc: imx: add i.MX93 media blk ctrl driver")
> > Signed-off-by: Dong Aisheng <aisheng.dong@xxxxxxx>
> > Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
> > ---
> >  drivers/pmdomain/imx/imx93-blk-ctrl.c | 29
> > +++++++++++++++++++++++++++
> >  1 file changed, 29 insertions(+)
> >
> > diff --git a/drivers/pmdomain/imx/imx93-blk-ctrl.c
> > b/drivers/pmdomain/imx/imx93-blk-ctrl.c
> > index 904ffa55b8f4..34ac7b722b90 100644
> > --- a/drivers/pmdomain/imx/imx93-blk-ctrl.c
> > +++ b/drivers/pmdomain/imx/imx93-blk-ctrl.c
> > @@ -424,6 +424,34 @@ static const struct imx93_blk_ctrl_data
> imx93_media_blk_ctl_dev_data = {
> >         .reg_access_table = &imx93_media_blk_ctl_access_table,
> >  };
> >
> > +static int imx93_blk_ctrl_suspend(struct device *dev) {
> > +       struct imx93_blk_ctrl *bc = dev_get_drvdata(dev);
> > +
> > +       /*
> > +        * This may look strange, but is done so the generic PM_SLEEP
> code
> > +        * can power down our domains and more importantly power
> them up again
> > +        * after resume, without tripping over our usage of runtime PM
> to
> > +        * control the upstream GPC domains. Things happen in the
> right order
> > +        * in the system suspend/resume paths due to the device
> parent/child
> > +        * hierarchy.
> > +        */
> > +       return pm_runtime_resume_and_get(bc->dev);
> 
> The reason why we *don't* use a regular parent/child setup of the PM
> domains (genpds) to control power-on/off, is because there seems to
> be a specific sequence that needs to be followed. So, instead we are
> using runtime PM to control the power for the parent PM domain.  See
> the comment in imx93_blk_ctrl_probe().

This was to follow i.MX8M implementation, but parent/child here
should be better here. After rethinking about this, i.MX93
not has the HW limitation as i.MX8M, so parent/child
could be used here.

> 
> I have to admit, it all looks strange to me and seems also very fragile.
> 
> That said, why doesn't the sequence matter any longer during system
> suspend/resume. Or maybe the sequence doesn't really matter after all?

It matters, the blk ctrl should be child of GPC power domain.

Thanks,
Peng.

> 
> > +}
> > +
> > +static int imx93_blk_ctrl_resume(struct device *dev) {
> > +       struct imx93_blk_ctrl *bc = dev_get_drvdata(dev);
> > +
> > +       pm_runtime_put(bc->dev);
> > +
> > +       return 0;
> > +}
> > +
> > +static const struct dev_pm_ops imx93_blk_ctrl_pm_ops = {
> > +       SYSTEM_SLEEP_PM_OPS(imx93_blk_ctrl_suspend,
> > +imx93_blk_ctrl_resume) };
> > +
> >  static const struct of_device_id imx93_blk_ctrl_of_match[] = {
> >         {
> >                 .compatible = "fsl,imx93-media-blk-ctrl", @@ -439,6
> > +467,7 @@ static struct platform_driver imx93_blk_ctrl_driver = {
> >         .remove_new = imx93_blk_ctrl_remove,
> >         .driver = {
> >                 .name = "imx93-blk-ctrl",
> > +               .pm = pm_sleep_ptr(&imx93_blk_ctrl_pm_ops),
> >                 .of_match_table = imx93_blk_ctrl_of_match,
> >         },
> >  };
> > --
> > 2.37.1
> >
> 
> Kind regards
> Uffe