On Thu, Nov 01, 2012 at 01:46:26, Balbi, Felipe wrote: > 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@xxxxxx> 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@xxxxxx> > > > > > > this looks good to my eyes, hopefully I haven't missed anything: > > > > > > Reviewed-by: Felipe Balbi <balbi@xxxxxx> > > > > > > > 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. Same here. Description is required in commit message since it will help in during git bisect. > > -- > balbi > Regards, Gururaja -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
