Re: [PATCH] ARM: dts: fix MMC2 regulators for Exynos5420 Arndale Octa board

[Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>]

Hi,

On Thursday, October 02, 2014 09:45:41 AM Doug Anderson wrote:
> Bartiomiej
> 
> On Thu, Oct 2, 2014 at 9:39 AM, Bartlomiej Zolnierkiewicz
> <b.zolnierkie@samsung.com> wrote:
> > On Thursday, October 02, 2014 09:19:08 AM Doug Anderson wrote:
> >> Bartiomiej,
> >>
> >> On Thu, Oct 2, 2014 at 9:10 AM, Bartlomiej Zolnierkiewicz
> >> <b.zolnierkie@samsung.com> wrote:
> >> > Regulators for MMC2 (SD card) are PVDD_TFLASH_2V8 (LDO19) for vmmc
> >> > and PVDD_APIO_MMCOFF_2V8 (LDO13) for vqmmc.  Currently the device
> >> > tree entry for MMC2 uses PVDD_PRE_1V8 (LDO10) for vmmc and vqmmc is
> >> > not specified.  Fix it.
> >> >
> >> > Without this patch:
> >> > - "mmc: dw_mmc: use mmc_regulator_get_supply to handle regulators"
> >> >   patch causes a SD card detection to fail
> >> > - "mmc: dw_mmc: Support voltage changes" patch causes a boot hang
> >> >
> >> > This patch fixes both above problems.
> >> >
> >> > Suggested-by: Doug Anderson <dianders@google.com>
> >> > Cc: Yuvaraj Kumar C D <yuvaraj.cd@samsung.com>
> >> > Cc: Ulf Hansson <ulf.hansson@linaro.org>
> >> > Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> >> > Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
> >> > ---
> >> >  arch/arm/boot/dts/exynos5420-arndale-octa.dts |    3 ++-
> >> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >> >
> >> > Index: b/arch/arm/boot/dts/exynos5420-arndale-octa.dts
> >> > ===================================================================
> >> > --- a/arch/arm/boot/dts/exynos5420-arndale-octa.dts     2014-10-02 15:44:53.014826886 +0200
> >> > +++ b/arch/arm/boot/dts/exynos5420-arndale-octa.dts     2014-10-02 17:35:24.110600398 +0200
> >> > @@ -74,7 +74,8 @@
> >> >                 samsung,dw-mshc-ddr-timing = <1 2>;
> >> >                 pinctrl-names = "default";
> >> >                 pinctrl-0 = <&sd2_clk &sd2_cmd &sd2_cd &sd2_bus4>;
> >> > -               vmmc-supply = <&ldo10_reg>;
> >> > +               vmmc-supply = <&ldo19_reg>;
> >> > +               vqmmc-supply = <&ldo13_reg>;
> >>
> >> This looks right to me.  ...but I notice that ldo13 and ldo19 are not
> >> "always-on" in the DTS.  Are you sure card detect works for you if you
> >> eject your card and try to put it back in?
> >>
> >> ...eventually the "always-on" won't be needed, but for now I think it is...
> >
> > Card detection works fine without "always-on".
> 
> That's weird.
> 
> 1. In the schematics I see XMMC2CDN has an external pullup to PVDD_TFLASH_2V8.
> 
> 2. The internal pullup should (I think) be to VDDQ_MMC2 which is
> PVDD_APIO_MMCOFF_2V8.
> 
> 3. In (51da224 mmc: dw_mmc: use mmc_regulator_get_supply to handle
> regulators) we should be turning off both regulators in
> "MMC_POWER_OFF".
> 
> 4. If I understand correctly MMC_POWER_OFF is called when the card is
> ejected, which means that both regulators should be off when the card
> is ejected.
> 
> 5. I don't think card detect can work if neither regulator is powered.
> 
> 
> One of the above points must be wrong.  Any idea which one?  Can you
> check to see if MMC_POWER_OFF is called for you when the card is
> ejected?  Can you check to see if these regulators are off?

MMC_POWER_OFF is called on card removal and both regulators get disabled
(I have verified that they are really off with regulator_is_enabled() which
returns 1 before and 0 after disabling regulator).  It seems that 5. is
wrong?

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics