On Thursday 27 November 2014 02:12:04 Tony Lindgren wrote:

* Pali Roh?r [off-list ref] [141126 15:40]:

quoted

With enabled CONFIG_ARM_APPENDED_DTB=y file /proc/atags is
missing.

OK I guess it should not be needed for DT based booting.

If I do not enable CONFIG_ARM_APPENDED_DTB=y then kernel is 
booting in legacy mode (not in DT).

quoted

quoted

The build_tag_list() should parse ATAG_REVISION and then
parse_tag_revision() should copy it to system_rev. Maybe
try adding some printks to see if those functions get
called?

Now I see... Problem is that build_tag_list() is called from
convert_to_tag_list() which is called from
setup_machine_tags() which is called from setup_arch() only
if setup_machine_fdt() call fails. And it fails for *non*
DT boot. You can check this chain too.

Thinking about this probably the best long term solution is
to pass optional board_revision in the kernel cmdline that
can be parsed early and copied to system_rev variable.

Not possible. Our bootloader is closed & proprietary. I tried to 
replace it with u-boot I was not able to do that. So we will use 
that Nokia closed bootloader forever and it can provide data only 
in ATAG structure.

Or if you can think of some other way to get it, we can set
system_rev in pdata-quirks.c.

Or maybe add some code to copy the ATAGs somewhere where
they are out of the way and don't conflict with the device
tree data? Then we can query ATAG_REVISION from pdata-quirks.c
and set system_rev.

Regards,

Tony

If we are able to read ATAG from pdata-quirks, then we can parse 
it there and fix problems... But I do not know if address of ATAG 
structure is available there...

-- 
Pali Roh?r
pali.rohar at gmail.com
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