[U-Boot] [PATCH 2/2] omapl138_lcdk: Set uboot raw mmc sector to 0x41

[Tom Rini]

On Mon, Feb 13, 2017 at 05:11:09PM +0100, Axel Haslam wrote:
> Hi Tom
> 
> On Mon, Feb 13, 2017 at 3:23 PM, Axel Haslam <ahaslam at baylibre.com> wrote:
> > On Mon, Feb 13, 2017 at 3:17 PM, Tom Rini <trini at konsulko.com> wrote:
> >> On Mon, Feb 13, 2017 at 03:14:28PM +0100, Axel Haslam wrote:
> >>> Hi Tom
> >>>
> >>> On Mon, Feb 13, 2017 at 2:23 PM, Tom Rini <trini at konsulko.com> wrote:
> >>> > On Mon, Feb 13, 2017 at 11:44:57AM +0100, Axel Haslam wrote:
> >>> >> The uboot binary on the AIS file starts at offset 0x8000.
> >>> >> This would be sector 0x40 on a mmc card with 512 bytes per
> >>> >> sector: 0x8000/0x200 = 0x40.
> >>> >>
> >>> >> But because we usually skip the first mmc sector to preserve
> >>> >> the partition table, the ais image is written starting
> >>> >> on sector 0x1, and the u-boot binary ends up at sector 0x41.
> >>> >>
> >>> >> Set the address of the u-boot binary to 0x41 so that spl
> >>> >> can correctly jump to it.
> >>> >>
> >>> >> Signed-off-by: Axel Haslam <ahaslam at baylibre.com>
> >>> >> ---
> >>> >>  configs/omapl138_lcdk_defconfig | 2 +-
> >>> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>> >>
> >>> >> diff --git a/configs/omapl138_lcdk_defconfig b/configs/omapl138_lcdk_defconfig
> >>> >> index d20af19..a249ebd 100644
> >>> >> --- a/configs/omapl138_lcdk_defconfig
> >>> >> +++ b/configs/omapl138_lcdk_defconfig
> >>> >> @@ -12,7 +12,7 @@ CONFIG_VERSION_VARIABLE=y
> >>> >>  # CONFIG_DISPLAY_BOARDINFO is not set
> >>> >>  CONFIG_BOARD_EARLY_INIT_F=y
> >>> >>  CONFIG_SPL=y
> >>> >> -CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR=0xb5
> >>> >> +CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR=0x41
> >>> >
> >>> > Since we're changing a default here, and one that will lead to
> >>> > non-booting boards if you don't notice, where did the old value come
> >>> > from, and is it actually in use anywhere?  Thanks!
> >>>
> >>> I think the "old offset" would be correct when you copy the AIS image
> >>> to the sd card using the uflash tool from TI. This tool adds some extra
> >>> space at the start of the mmc for UBL configuration settings, which does
> >>> not seem to be needed for the lcdk. The generated AIS image with SPL
> >>> can boot the board directly and we can just copy the resulting AIS
> >>> to the sdcard with the "dd" command.
> >>
> >> Ah yes, that tool.  What is the drive for not being compatible with that
> >> tool in terms of offset?  With binman it should be easy enough to have
> >> U-Boot generate a binary with sufficient padding between items.  Thanks!
> >>
> >
> > Good point.  i will try that instead. Thanks for the tip.
> 
> I looked at how the uflash tool works and it takes as input the AIS
> image, which i think means we would have to have yet another
> type of image specific for mmc that adds the padding.
> 
> An alternative to this would be just to document that to
> write the AIS  image we need to skip 117 sectors, like so:
> 
> sudo dd if=./u-boot.ais of=/dev/mmcblk0 seek=117 bs=512
> 
> this would make u-boot fall into sector 0xb5, which would be
> exactly the same that is uflash ends up writing uboot to, and
> there would be no defconfig changes.
> 
> Would this be acceptable?

Yes, changing the instructions so that we write to the same location as
the TI tool and not need to change the defconfig would be the preferred
approach, thanks!

-- 
Tom
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