[U-Boot] [PATCH] serial: ns16550: Add register shift variable

[Andy Shevchenko <andy.shevchenko@gmail.com>]

On Mon, Jul 16, 2018 at 6:04 PM, Alexey Brodkin
<Alexey.Brodkin@synopsys.com> wrote:

>> > Any chance to get a reference to the commit in Linux kernel that introduces that change?
>> >
>> In fact I believe that the <reg-shift> property never existed in the
>> am33xx.dtsi file from Linux. U-Boot commit 85cf0e6299 shows that the
>> property has been added to U-Boot's am33xx.dtsi file. The commit log
>> clearly states why this happened:
>>
>> "With the commit 'c7b9686d5d48 ("ns16550: unify serial_omap")' all
>> TI platforms are broken with DM/DT boot as ns16550 driver expects
>> reg-shift from DT which is not populated for TI platforms.
>> Earlier it worked as it was hard coded to 2 in serial-omap
>> driver. So adding the reg-shift to serial nodes for dra7, am4372
>> and am33xx dtsi files. Tested this patch on am437x-sk-evm,
>> am437x-gp-evm, am335x-boneblack, dra74x-evm and dra72x-evm."
>
> Ok so this has nothing to do with changes in Linux kernel I guess.
> Why don't we go the other way around and not just submit
> a change to .dts files in Linux kernel that are missing required properties?

You may change DTSi files in the Linux kernel sources tree, but you
wouldn't be able to fix all DTB:s in the wild.
In this case Linux should have a fallback to the previous value in
case property is not found.

-- 
With Best Regards,
Andy Shevchenko