[PATCH V3] mmc: omap_hsmmc: Enable HSPE bit for high speed cards

[Felipe Balbi]

Hi,

On Thu, Nov 01, 2012 at 01:21:36AM +0530, Venkatraman S wrote:
> On Wed, Oct 31, 2012 at 5:56 PM, Felipe Balbi <balbi at ti.com> wrote:
> > Hi,
> >
> > On Wed, Oct 31, 2012 at 05:27:36PM +0530, Hebbar, Gururaja wrote:
> >> HSMMC IP on AM33xx need a special setting to handle High-speed cards.
> >> Other platforms like TI81xx, OMAP4 may need this as-well. This depends
> >> on the HSMMC IP timing closure done for the high speed cards.
> >>
> >> From AM335x TRM (SPRUH73F - 18.3.12 Output Signals Generation)
> >>
> >> The MMC/SD/SDIO output signals can be driven on either falling edge or
> >> rising edge depending on the SD_HCTL[2] HSPE bit. This feature allows
> >> to reach better timing performance, and thus to increase data transfer
> >> frequency.
> >>
> >> There are few pre-requisites for enabling the HSPE bit
> >> - Controller should support High-Speed-Enable Bit and
> >> - Controller should not be using DDR Mode and
> >> - Controller should advertise that it supports High Speed in
> >>   capabilities register and
> >> - MMC/SD clock coming out of controller > 25MHz
> >>
> >> Note:
> >> The implementation reuses the output of calc_divisor() so as to reduce
> >> code addition.
> >>
> >> Signed-off-by: Hebbar, Gururaja <gururaja.hebbar at ti.com>
> >
> > this looks good to my eyes, hopefully I haven't missed anything:
> >
> > Reviewed-by: Felipe Balbi <balbi at ti.com>
> >
> 
> Except for the excessively verbose comments which are just duplicating the code,
> <Quote>
> >> +      * Enable High-Speed Support
> >> +      * Pre-Requisites
> >> +      *      - Controller should support High-Speed-Enable Bit
> >> +      *      - Controller should not be using DDR Mode
> >> +      *      - Controller should advertise that it supports High Speed
> >> +      *        in capabilities register
> >> +      *      - MMC/SD clock coming out of controller > 25MHz
> >> +      */
> </Quote>
> 
> I'm ok with this patch as well. I'm putting a few patches under test
> including this one,
> and will send it to Chris as part of that series.
> I'll strip out the above mentioned comments, unless there are any
> objections.

please don't. Detailing the pre-requisites for getting HSP mode working
isn't bad at all. Should someone decide to change the behavior and ends
up breaking it, the comment will help putting things back together.

my 2 cents, you've got the final decision though.

-- 
balbi
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 836 bytes
Desc: Digital signature
URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20121031/341e1607/attachment-0001.sig>