Re: [PATCH v2 0/6] Add support of inverting power control and some minor cleanup

[Shawn Lin]

On 2016/8/11 18:08, Jaehoon Chung wrote:
> Hi Shawn,
>
> On 08/09/2016 10:49 AM, Shawn Lin wrote:
> > Hi,
> >
> > On 2016/8/8 18:24, Jaehoon Chung wrote:
> > > Hi Shawn,
> > >
> > > On 08/07/2016 10:33 AM, Shawn Lin wrote:
> > > > By default, dw_mmc outputs high level voltage to indicate powering
> > > > up the card and outputs low level vcltage to indicate powering
> > > > off the card. But that is not always correct. The power io should
> > > > be able to control different kind of hw components to supply or
> > > > cutoff power to the card. We have boards that need this patchset
> > > > to make the power control correct. Meanwhile let's expose it to
> > > > DT for board-specific usage.
> > >
> > > I have a question for this patch-set. Does DWMMC IP support to invert ON/OFF at Power Enable register?
> >
> > No.
> >
> > > Hmm..Well, if use the DW_MMC_CARD_PWR_INVERT, it should also be the similar behavior with Quirks.
> >
> > yup, it makes the power control more complicated than before. :(
> >
> > > Other flags are related with dwmmc IP. But this flag (DW_MMC_CARD_PWR_INVERT) is not related with IP side.
> > > I understood why you needs to add this flag..Is rockchip designed to invert the power controlling?
> >
> > We don't invert the power controlling but our customers do.
> > The HW componet looks like some discrete LDOs which enable the related
> > power supply when outputing low voltage from pwren..
>
> Is it related with PWREN register?
> I'm checking the TRM for PWREN register..
>
> "Optional feature; ports can be used as general-purpose outputs."
>
> Does it use the ports as GPIO?
>
> > > But it's not general case. We can discuss about this.
> >
> > I have a solution which is to add gpio power control for slot-gpio of
> > mmc core. once finished, we could add pwr_cap_invert just like what we
> > did for cd/wp invert control..
>
> I'm not sure that it's right that add the gpio power control into mmc core.
> slot-gpio? i think it can use the regulator framework with gpio.

yup, I'm looking this and seems it's fine to register a regulator-gpio
and stuff it for vmmc-supply of sdmmc. I will test it, really helpful.

thanks!

> I don't have a lot knowledge of power, but it might be controlled whether active is low or high.
> So i think it doesn't need to add for entire mmc controller.
>
> Best Regards,
> Jaehoon Chung
>
> > Then we could remove PWREN from the default state of
> > pinctrl inside the sdmmc dt node, and let dwmmc request gpio power
> > control stuff after paring the property for pwr_cap_invert..
> >
> > More over, it well fit for all mmc host's requirement of gpio
> > power control and inverted control if they want it. :)
> >
> >
> > That should be legit for us?
> > If it sounds ok to you and Ulf, I will come up with a RFC one for
> > community to comment it.:)
> >
> > > Best Regards,
> > > Jaehoon Chung
> > >
> > > > Changes in v2:
> > > > - fix copy-paste err and typo
> > > >
> > > > Shawn Lin (6):
> > > >   dt-bindings: rockchip-dw-mshc: add description of
> > > >     rockchip,power-invert
> > > >   mmc: dw_mmc: cleanup power setting of set_ios callback
> > > >   mmc: dw_mmc: split out dw_mci_set_power
> > > >   mmc: dw_mmc: split out dw_mci_set_power_reg
> > > >   mmc: dw_mmc: support inverted power control
> > > >   mmc: dw_mmc-rockchip: add parsing of power control from DT
> > > >
> > > >  .../devicetree/bindings/mmc/rockchip-dw-mshc.txt   |   6 +
> > > >  drivers/mmc/host/dw_mmc-rockchip.c                 |   8 ++
> > > >  drivers/mmc/host/dw_mmc.c                          | 134 ++++++++++++---------
> > > >  drivers/mmc/host/dw_mmc.h                          |   1 +
> > > >  4 files changed, 90 insertions(+), 59 deletions(-)
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at  http://vger.kernel.org/majordomo-info.html


--
Best Regards
Shawn Lin