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

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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



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