[U-Boot] [PATCH v3 2/3] dfu: ram support

[Lukasz Majewski <l.majewski@samsung.com>]

Hi Afzal,

> 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.
> 
> Signed-off-by: Afzal Mohammed <afzal.mohd.ma@gmail.com>
> Cc: Marek Vasut <marex@denx.de>
> Cc: Lukasz Majewski <l.majewski@samsung.com>
> Cc: Pantelis Antoniou <panto@antoniou-consulting.com>
> ---
> 
> v3: error used instead of printf
> v2: remove read/write enumerator define's, instead use new common ones

Acked-by: Lukasz Majewski <l.majewski@samsung.com>

-- 
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group