Re: [PATCH v4] mmc: dw_mmc: force setup bus if active slots exist

[Shawn Lin]

On 2017/1/9 13:41, Jaehoon Chung wrote:
> On 01/09/2017 12:39 PM, Ziyuan wrote:
> > On 01/05/2017 03:34 PM, Shawn Lin wrote:
> > > On 2017/1/5 15:23, Ziyuan Xu wrote:
> > > > It's necessary to setup bus if any slots are present.
> > > > - update clock after ctrl reset
> > > > - if the host has genpd node, we can guarantee the clock is available
> > > > before starting request. Otherwies, the clock register is reset once
> > > > power off the pd, and host can't output the active clock during
> > > > communication.
> > > >
> > > > fixes: e9ed8835e990 ("mmc: dw_mmc: add runtime PM callback")
> > > > Reported-by: Randy Li <randy.li@xxxxxxxxxxxxxx>
> > > > Signed-off-by: Ziyuan Xu <xzy.xu@xxxxxxxxxxxxxx>
> > > >
> > > > ---
> > > > Hi guys,
> > > >
> > > > I found a similar issue on rk3399 platform, which has a genpd node for
> > > > SD card host. Power off-on pd will reset the registers to a default
> > > > value (ie. CLKENA), so that the host can't output the active clock
> > > > during communication.
> > >
> > > Indeed, Caesar recently introduced all the genpd for rk3399 platform,
> > > so we need to restore them.
> > >
> > > > So we need to setup bus in rpm resume. It also wraps the update clock
> > > > behaviour which I did in V3.
> > > >
> > > > Thanks,
> > > > Ziyuan Xu
> > > >
> > > >
> > > > Changes in v4:
> > > > - update commit message
> > > > - fix SD host rpm resume can't work
> > > >
> > > > Changes in v3:
> > > > - only reset host with active slot.
> > > >
> > > > Changes in v2:
> > > > - update the commit message
> > > > - use dw_mci_reset instead of dw_mci_ctrl_reset
> > > >
> > > >  drivers/mmc/host/dw_mmc.c | 6 +++---
> > > >  1 file changed, 3 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> > > > index b44306b..b6053b3 100644
> > > > --- a/drivers/mmc/host/dw_mmc.c
> > > > +++ b/drivers/mmc/host/dw_mmc.c
> > > > @@ -3354,10 +3354,10 @@ int dw_mci_runtime_resume(struct device *dev)
> > > >
> > > >          if (!slot)
> > > >              continue;
> > > > -        if (slot->mmc->pm_flags & MMC_PM_KEEP_POWER) {
> > > > +        if (slot->mmc->pm_flags & MMC_PM_KEEP_POWER)
> > > >              dw_mci_set_ios(slot->mmc, &slot->mmc->ios);
> > > > -            dw_mci_setup_bus(slot, true);
> > > > -        }
> > > > +        /* Force setup bus to guarantee available clock output */
> > > > +        dw_mci_setup_bus(slot, true);
> > >
> > > So the spamming message about
> > >
> > > "Bus speed (slot %d) = %dHz (slot req %dHz, actual %dHZ div = %d)\n"
> > >
> > > will always be there, right? So you could append a new patch to shut
> > > up it as I think it's useless no matter for system pm or rpm to print
> > > it.  How about?
> >
> > Fine, it's favourable with dev_vdbg if the dw_mmc rpm is enabled.
> > Hi Jaehoon,
> > What's your opinion? If you think this patch and shawn's advice are acceptable, I will send the v5 patch.
>
> I don't agreed to use dev_vdbg()..but it needs not to display at everytime.
> Hmm..It needs to consider more..because we needs to see the clock value when it's initialized.

A very stright-forward way is to pass a flag to shut up the spamming
log when it's called from the PM context?

> Best Regards,
> Jaehoon Chung
>
> > BR
> > Ziyuan Xu
> >
> > > >      }
> > > >
> > > >      /* Now that slots are all setup, we can enable card detect */


--
Best Regards
Shawn Lin