[U-Boot] [PATCH] spl: if MMCSD_MODE_RAW fails, try MMCSD_MODE_FS, if available

[Nikita Kiryanov <nikita@compulab.co.il>]

On Thu, Feb 18, 2016 at 09:36:01AM -0500, Tom Rini wrote:
> On Thu, Feb 18, 2016 at 04:25:29PM +0200, Nikita Kiryanov wrote:
> > On Thu, Feb 18, 2016 at 02:31:08PM +0100, Guillaume Gardet wrote:
> > > 
> > > 
> > > Le 18/02/2016 14:07, Nikita Kiryanov a ?crit :
> > > >On Thu, Feb 18, 2016 at 11:06:32AM +0100, Guillaume Gardet wrote:
> > > >>Hi Tom, Nikita ,
> > > >>
> > > >>Le 18/02/2016 10:19, Nikita Kiryanov a ?crit :
> > > >>>Hi Tom, Guillaume,
> > > >>>
> > > >>>On Wed, Feb 17, 2016 at 03:27:22PM -0500, Tom Rini wrote:
> > > >>>>On Wed, Feb 17, 2016 at 09:09:27AM +0100, Guillaume GARDET wrote:
> > > >>>>
> > > >>>>>Since commit fd61d39970b9901217efc7536d9f3a61b4e1752a:
> > > >>>>>         spl: mmc: add break statements in spl_mmc_load_image()
> > > >>>>>RAW and FS boot modes are now exclusive again. So, if MMCSD_MODE_RAW fails, the
> > > >>>>>board hangs. This patch allows to try MMCSD_MODE_FS then, if available.
> > > >>>>>
> > > >>>>>It has been tested on a beaglebone black to boot on an EXT partition.
> > > >>>>>
> > > >>>>>Signed-off-by: Guillaume GARDET <guillaume.gardet@free.fr>
> > > >>>>>Cc: Tom Rini <trini@konsulko.com>
> > > >>>>>Cc: Nikita Kiryanov <nikita@compulab.co.il>
> > > >>>>>Cc: Igor Grinberg <grinberg@compulab.co.il>
> > > >>>>>Cc: Paul Kocialkowski <contact@paulk.fr>
> > > >>>>>Cc: Pantelis Antoniou <panto@antoniou-consulting.com>
> > > >>>>>Cc: Simon Glass <sjg@chromium.org>
> > > >>>>>Cc: Matwey V. Kornilov <matwey.kornilov@gmail.com>
> > > >>>>>
> > > >>>>>---
> > > >>>>>  common/spl/spl_mmc.c | 2 +-
> > > >>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
> > > >>>>>
> > > >>>>>diff --git a/common/spl/spl_mmc.c b/common/spl/spl_mmc.c
> > > >>>>>index c3931c6..2eef0f2 100644
> > > >>>>>--- a/common/spl/spl_mmc.c
> > > >>>>>+++ b/common/spl/spl_mmc.c
> > > >>>>>@@ -284,7 +284,7 @@ int spl_mmc_load_image(u32 boot_device)
> > > >>>>>  		if (!err)
> > > >>>>>  			return err;
> > > >>>>>  #endif
> > > >>>>>-		break;
> > > >>>>>+		/* Fall through */
> > > >>>>>  	case MMCSD_MODE_FS:
> > > >>>>>  		debug("spl: mmc boot mode: fs\n");
> > > >>>>This also essentially reverts fd61d399.  So Nikita, was there a specific
> > > >>>>use case that was broken before, or was the code just unclear in
> > > >>>>intentions here?  Thanks!
> > > >>>There was no broken use case that I'm aware of. The change was made as
> > > >>>part of a code improvement series and was meant to address what I
> > > >>>consider to be bad and problematic design. Instead of reverting it
> > > >>>though, how about implementing something similar to what I did in the
> > > >>>main common/spl/spl.c:board_init_r()? You would have a weak function
> > > >>>that will default to the original spl_boot_mode() if not overridden,
> > > >>>and allow the user to define a sequence of boot modes otherwise.
> > > >>The thing is you broke a wanted behavior currently in use. So, the priority is to come back to the previous behavior.
> > > >Could you add a comment indicating that this is wanted behavior that
> > > >has a user, and who the user is?
> > > 
> > > Not sure what you mean.
> > 
> > I mean something like:
> > /* If raw mode fails, try fs mode. Some boards, such as beaglebone black,
> >  * depend on this funcitonality.
> >  */
> 
> But it's not board specific, it's use-case specific.

The comment I proposed does not suggest it's board specific, just that
this specific use case is used by someone.

> instead of shoving both SPL and U-Boot into the correct magic raw
> location, just shove SPL there and let U-Boot itself be in the /boot
> partition.  This is just as applicable on say imx6 as it is on TI parts.

I don't think that's clear enough that this is the purpose of the
missing break statement. It's a little too implicit. What I'm suggesting
is that we make it a bit more explicit, barring a rewrite.

> 
> -- 
> Tom