Re: [PATCH V2] arm64: dts: qcom: sc7280: Add nodes for eMMC and SD card

[sbhanu]

On 2021-03-25 21:47, Doug Anderson wrote:
> Hi,
>
> On Wed, Mar 24, 2021 at 8:59 PM Veerabhadrarao Badiganti
> <vbadigan@xxxxxxxxxxxxxx> wrote:
> > >> +                       clocks = <&gcc GCC_SDCC1_APPS_CLK>,
> > >> +                                       <&gcc GCC_SDCC1_AHB_CLK>,
> > >> +                                       <&rpmhcc RPMH_CXO_CLK>;
> > >> +                       clock-names = "core", "iface", "xo";
> > > I'm curious: why is the "xo" clock needed here but not for sc7180?
> > Actually its needed even for sc7180. We are making use of this clock 
> > in
> > msm_init_cm_dll()
> > The default PoR value is also same as calculated value for
> > HS200/HS400/SDR104 modes.
> > But just not to rely on default register values we need this entry.
>
> Can you post a patch for sc7180?
sure will post a patch for sc7180.
> > >> +                       bus-width = <4>;
> > >> +
> > >> +                       no-mmc;
> > >> +                       no-sdio;
> > > Similar question to above: why exactly would mmc not work? Are you
> > > saying that if someone hooked this up to a full sized SD card slot and
> > > placed an MMC card into the slot that it wouldn't work? Similar
> > > question about SDIO. If someone placed an external SDIO card into your
> > > slot, would it not work?
> > >
> > As mentioned above, its just to optimize SDcard scan time a little.
>
> OK. ...but while the eMMC one can make sense since the eMMC is
> soldered down (but in the board dts file, not in the SoC dtsi file) I
> think you should just remove these for SD card because:
>
> 1. Even if only a uSD slot is exposed it's still _possible_ for
> someone to insert a card that uses MMC or SDIO signaling. If nothing
> else I have a (probably non-compliant) adapter that plugs into a uSD
> slot and provides a full sided SD slot. I could plug an MMC card or
> SDIO card in.
>
> 2. Presumably the SD card scan time optimization is tiny.
sure will remove these for SD card and will move eMMC flags(no-sd and 
no-sdio) to board dts file.
> -Doug