On Thu, Sep 27, 2012 at 16:31:14, Koen Kooi wrote: > > Op 26 sep. 2012, om 13:37 heeft "Hebbar, Gururaja" <gururaja.hebbar@xxxxxx> het volgende geschreven: > > > On Wed, Sep 12, 2012 at 17:32:38, Hebbar, Gururaja wrote: > >> On Wed, Sep 12, 2012 at 14:19:51, S, Venkatraman wrote: > >>> On Tue, Sep 4, 2012 at 6:39 PM, Hebbar, Gururaja <gururaja.hebbar@xxxxxx> 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 > >>>> > >>> > >>> The patch is well written. But then, I don't see a need for a DT > >>> binding for this feature. > >> > >> My reasons for DT Binding > >> 1. Not all platforms using this driver has this bit (OMAP2) > >> 2. Not all platforms using this driver needs this bit to be enabled (OMAP4) > >> 3. Platforms which require this bit this to be set needs a method to inform > >> driver. > >> > >> In order to not disturb old/unsupported platforms, I chose this DT method. > >> > >>> By definition, HS implies 25MHz or above, so that check seems to be > >>> redundant as well. > >> > >> There are chances that the platform Max Clock output from HSMMC IP is < than > >> 25 MHz even if the card is High Speed. In such cases it would be better to > >> Confirm that the Clock output is actually > 25 MHz > >> > >> Kindly correct me if I am wrong. > >> > >>> Meanwhile, I'll check with HSPE enabled on OMAP. > >>> > > > > Gentle Ping. > > > > Matt Poter recently submitted EDMA related patches as RFC. He confirmed that > > basic mmc is working on AM335x with his edma patches. > > > > Above patch is required to get High-speed cards working on AM335x. > > > > I haven't seen any review comments for this. Can this be pulled in for 3.7? > > I had trouble applying this to 3.6-rc7, is that a known problem and should I try linux-next? I just applied it applied it on Linux-next/master (locally merged with linux-omap-dt branch). It applied without any issues. > > regards, > > Koen 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
