RE: Question regarding SDR104 bus speed mode

Subhash Jadavani
2011-07-20T07:22:11Z

> -----Original Message-----
> From: linux-mmc-owner@vger.kernel.org [mailto:linux-mmc-
> owner@vger.kernel.org] On Behalf Of Philip Rakity
> Sent: Monday, July 18, 2011 8:57 PM
> To: Subhash Jadavani
> Cc: linux-mmc@vger.kernel.org; arindam.nath@amd.com
> Subject: Re: Question regarding SDR104 bus speed mode
>
>
> On Jul 17, 2011, at 10:21 PM, Subhash Jadavani wrote:
>
> > Arindam/Philips,
> >
> > Can you help me with below query?
> >
> > Regards,
> > Subhash
> >
> >> -----Original Message-----
> >> From: linux-mmc-owner@vger.kernel.org [mailto:linux-mmc-
> >> owner@vger.kernel.org] On Behalf Of Subhash Jadavani
> >> Sent: Thursday, July 14, 2011 5:09 PM
> >> To: linux-mmc@vger.kernel.org; prakity@marvell.com;
> >> arindam.nath@amd.com
> >> Subject: Question regarding SDR104 bus speed mode
> >>
> >> Hi Arindam, Philips and All,
> >>
> >> According to SD 3.0 spec (section 3.9.6), cards may require current
> >> upto
> >> 800 mA while running in SDR104. However Max. supported current from
> >> PMIC
> >> regulator connected to sd card slot on my board is 600mA.
> >>
> >> I have these questions:
> >> 1. So does this mean we can't support the SDR104 mode if regulator
> >> current
> >> driving capacity is not upto 800 mA?
> >>
> >> 2. I am able to make SD card run in SDR104 mode even if the max.
> >> current
> >> supplied by regulator is upto 600 mA. So is this 800mA requirement
> is
> >> **must** condition to support SDR104 mode reliably?
>
> Check the datasheet for the chip vendor you are using assuming the
> chip is soldered down on the board. Our our system the eMMC chip
> is much more flexible then the JEDEC spec allows.

Philips,
This is not for eMMC/MMC spec and cards. This is for SDR104 mode from SD3.0
spec. and relevant for SD UHS-I cards only.
Any comments of running SDR104 with 600mA driver current? Is this fine
according to SD3.0 spec?

>
> >>
> >> Regards,
> >> Subhash
> >>
> >> --
> >> Sent by a consultant of the Qualcomm Innovation Center, Inc.
> >> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
> >> Forum.
> >>
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