On Tue, Jul 11, 2017 at 02:42:44PM +0200, Ulf Hansson wrote:
> On 16 June 2017 at 09:29, Quentin Schulz
> <quentin.schulz@xxxxxxxxxxxxxxxxxx> wrote:
> > This adds deepest (Backup+Self-Refresh) PM support to the ATMEL SAMA5D2
> > SoC's SDHCI controller.
> >
> > When resuming from deepest state, it is required to restore preset
> > registers as the registers are lost since VDD core has been shut down
> > when entering deepest state on the SAMA5D2. The clocks need to be
> > reconfigured as well.
>
> Right, so compared to runtime resume there is some additional
> operations that is needed during system resume. Fair enough.
>
> However by looking at the changes below, you also change the system
> suspend operations, as it now calls sdhci_suspend_host(). Is that
> change needed? Then why?
>
> >
> > The other registers and init process are taken care of by the SDHCI
> > core.
> >
> > Signed-off-by: Quentin Schulz <quentin.schulz@xxxxxxxxxxxxxxxxxx>
> > ---
> > drivers/mmc/host/sdhci-of-at91.c | 34 ++++++++++++++++++++++++++++++++--
> > 1 file changed, 32 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/mmc/host/sdhci-of-at91.c b/drivers/mmc/host/sdhci-of-at91.c
> > index fb8c6011f13d..300513fc1068 100644
> > --- a/drivers/mmc/host/sdhci-of-at91.c
> > +++ b/drivers/mmc/host/sdhci-of-at91.c
> > @@ -207,6 +207,37 @@ static int sdhci_at91_set_clks_presets(struct device *dev)
> > }
> >
> > #ifdef CONFIG_PM
> > +static int sdhci_at91_suspend(struct device *dev)
> > +{
> > + struct sdhci_host *host = dev_get_drvdata(dev);
> > + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> > + struct sdhci_at91_priv *priv = sdhci_pltfm_priv(pltfm_host);
> > + int ret;
> > +
> > + ret = sdhci_suspend_host(host);
> > +
>
> This is wrong, you can't call sdhci_suspend_host() unless the device
> is runtime resumed...
>
> > + if (host->runtime_suspended)
> > + return ret;
>
> ... and this is weird...
>
> > +
> > + clk_disable_unprepare(priv->gck);
> > + clk_disable_unprepare(priv->hclock);
> > + clk_disable_unprepare(priv->mainck);
> > +
> > + return ret;
> > +}
> > +
> > +static int sdhci_at91_resume(struct device *dev)
> > +{
> > + struct sdhci_host *host = dev_get_drvdata(dev);
> > + int ret;
> > +
> > + ret = sdhci_at91_set_clks_presets(dev);
> > + if (ret)
> > + return ret;
>
> Instead of doing it like this, I suggest you set a new flag to true
> here, let's call it "restore_needed".
>
> In the ->runtime_resume() callback, you check the restore_needed flag
> and performs the extra operations in that case. When that's done, the
> ->runtime_resume() callback clears the flag, as to avoid the next
> runtime resume from unnecessary doing the extra operations.
>
> > +
> > + return sdhci_resume_host(host);
>
> Remove this and call pm_runtime_force_resume().
>
> > +}
> > +
> > static int sdhci_at91_runtime_suspend(struct device *dev)
> > {
> > struct sdhci_host *host = dev_get_drvdata(dev);
> > @@ -256,8 +287,7 @@ static int sdhci_at91_runtime_resume(struct device *dev)
> > #endif /* CONFIG_PM */
> >
> > static const struct dev_pm_ops sdhci_at91_dev_pm_ops = {
> > - SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
>
> Leave the pm_runtime_force_suspend() here, unless you have other
> reasons not being described in the change log, to change the system
> suspend operations.
I think we need to keep it to be able to set the restore_needed flag, isn't it?
Regards
Ludovic
>
> > - pm_runtime_force_resume)
> > + SET_SYSTEM_SLEEP_PM_OPS(sdhci_at91_suspend, sdhci_at91_resume)
> > SET_RUNTIME_PM_OPS(sdhci_at91_runtime_suspend,
> > sdhci_at91_runtime_resume,
> > NULL)
> > --
> > 2.11.0
> >
>
> Adopting my changes should simplify the code, avoid unnecessary
> resuming the device but instead deferring that until really needed via
> runtime PM.
>
> Kind regards
> Uffe
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