[U-Boot] [U-Boot,3/3] mmc: support writing sparse images

[Alex Kiernan]

On Mon, May 14, 2018 at 3:47 PM Tom Rini <trini at konsulko.com> wrote:

> On Mon, May 14, 2018 at 06:42:41PM +0530, Jassi Brar wrote:
> > Hi Tom,
> >
> > On Tue, May 8, 2018 at 10:45 PM, Tom Rini <trini at konsulko.com> wrote:
> > > On Fri, Apr 06, 2018 at 12:05:24PM +0530, jassisinghbrar at gmail.com
wrote:
> > >
> > >> From: Jassi Brar <jaswinder.singh at linaro.org>
> > >>
> > >> Provide an alternate path for sparse-images to be
> > >> written to MMC. For example, via tftp on platforms
> > >> that don't support fastboot protocol. Or when an
> > >> image is to written at some offset, rather than the
> > >> start of a partition.
> > >>
> > >> Signed-off-by: Jassi Brar <jaswinder.singh at linaro.org>
> > >
> > > Applied to u-boot/master, thanks!
> >
> > I see you modified the patch to protect the feature with
> > CONFIG_FASTBOOT_FLASH, which kills the purpose -- this feature is for
> > platforms that don't support fastboot.
> >
> > Do you want me to send the patch to revert the protection?

> Sorry, I guess maybe things weren't clear enough all around, and we
> should (functionally) revert patches 2 and 3 and try something
> different.  It is OK to say "lets make writing sparse images more widely
> available".  It's not OK to make every platform with MMC write grow a
> decent bit in binary size.  Making a quick pass at re-enabling things on
> a platform without fastboot support already grew things by nearly 2KiB.
> The other part which is I believe got me down this path was that without
> a change to common/Makefile to always (outside of SPL) include
> common/image-sparse.o things don't link.

> In sum, a new patch to add an option to allow people to opt-in for
> swrite would be good.  And please make sure to do something like:
> diff --git a/common/Makefile b/common/Makefile
> index d0681c7dd96a..92b2aa1ca8f0 100644
> --- a/common/Makefile
> +++ b/common/Makefile
> @@ -120,6 +120,7 @@ ifdef CONFIG_FASTBOOT_FLASH_NAND_DEV
>       obj-y += fb_nand.o
>       endif
>       endif
> +obj-$(CONFIG_MMC_WRITE) += image-sparse.o
>       endif

Isn't this just move image-sparse to lib and add a separate guard for it
(LIB_IMAGE_SPARSE?) which can be selected by both FASTBOOT and a new
command symbol (CMD_MMC_SWRITE)?

This is all overlapping with the UDP fastboot code I've been posting, so
I'd kinda like it to fit nicely with that, rather than have to refactor it
to fit something different!

--
Alex Kiernan