[U-Boot] [PATCH v4 0/3] dfu ram support

[Marek Vasut]

Dear Afzal Mohammed,

> Hi,
> 
> DFU spec mentions it as a method to upgrade firmware (software stored
> in writable non-volatile memory). It also says other potential uses of
> DFU is beyond scope of the spec.
> 
> Here such a beyond the scope use is being attempted - directly pumping
> binary images from host via USB to RAM. This facility is a developer
> centric one in that it gives advantage over upgrading non-volatile
> memory for testing new images every time during development and/or
> testing.
> 
> Directly putting image onto RAM would speed up upgrade process. This and
> convenience was the initial thoughts that led to doing this, speed
> improvement over MMC was only 1 second though - 6 sec on RAM as opposed
> to 7 sec on MMC in beagle bone, perhaps enabling cache and/or optimizing
> DFU framework to avoid multiple copy for ram (if worth) may help, and
> on other platforms and other boot media like NAND maybe improvement
> would be higher.
> 
> And for a platform that doesn't yet have proper DFU suppport for
> non-volatile media's, DFU to RAM can be used.
> 
> Another minor advantage would be to increase life of mmc/nand as it
> would be less used during development/testing.
> 
> usage: <image name> ram <start address> <size>
> eg. kernel ram 0x81000000 0x1000000
> 
> Downloading images to RAM using DFU is not something new, this is
> acheived in openmoko also.
> 
> DFU on RAM can be used for extracting RAM contents to host using dfu
> upload. Perhaps this can be extended to io for squeezing out register
> dump through usb, if it is worth.
> 
> In addition to ram support, a minor unification of dfu read/write enum's
> currently duplicated in mmc/nand is done, helping ram support too.
> 
> Also dfu ram support is added for am335x SoC based boards.
> 
> Based on: usb master branch
> 
> Regards
> Afzal

Will wait for Heiko's ACK and then apply for -next.

Best regards,
Marek Vasut