Op 26 sep. 2012, om 13:37 heeft "Hebbar, Gururaja" [off-list ref] het volgende geschreven:

On Wed, Sep 12, 2012 at 17:32:38, Hebbar, Gururaja wrote:

quoted

On Wed, Sep 12, 2012 at 14:19:51, S, Venkatraman wrote:

quoted

On Tue, Sep 4, 2012 at 6:39 PM, Hebbar, Gururaja [off-list ref] wrote:

quoted

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.

quoted

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.

quoted

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?

regards,

Koen