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

Alexey Brodkin Alexey.Brodkin at synopsys.com
Sun Jul 15 08:43:08 UTC 2018


Hi Tom, Felix, all

> -----Original Message-----
> From: Tom Rini [mailto:trini at konsulko.com]
> Sent: Saturday, July 14, 2018 6:50 PM
> To: Wolfgang Denk <wd at denx.de>
> Cc: Felix Brack <fb at ltec.ch>; u-boot at lists.denx.de; Stefan Roese <sr at denx.de>; Alexey Brodkin <Alexey.Brodkin at synopsys.com>;
> Alexander Graf <agraf at suse.de>; Michal Simek <michal.simek at xilinx.com>
> Subject: Re: [U-Boot] [PATCH] serial: ns16550: Add register shift variable
> 
> On Sat, Jul 14, 2018 at 12:47:21PM +0200, Wolfgang Denk wrote:
> > Dear Felix,
> >
> > In message <1531492980-16543-1-git-send-email-fb at ltec.ch> you wrote:
> > >
> > > The motivation for writing this patch originates in the
> > > effort of synchronizing U-Boot DT to Linux DT for am33xx SOCs.
> > > The current am33xx.dtsi file from U-Boot defines the <reg-shift>
> > > property for all UART nodes. The actual (4.18+) am33xx.dtsi
> > > file from Linux does not define <reg-shift> anymore. To prevent
> > > (probably difficult) changes in many .dts and .dtsi files once
> > > the synchronization is done, one can use this new variable. For
> > > the pdu001 board, for example, SYS_NS16550_REG_SHIFT is set
> > > to 2; no need to clutter U-Boot and board specific dts files
> > > with <reg-shift> properties.
> >
> > Does this mean that U-Boot will not be able to use the same DTB as
> > Linux?
> 
> To be clear, it's the other way around.  We can't use the Linux dtb/dts
> files as they've dropped (and in other cases, aren't adding) these
> properties as it's handled differently.

Any chance to get a reference to the commit in Linux kernel that introduces that change?

I still see a bunch of:
----------------------------->8----------------------
reg-shift = <2>;
reg-io-width = <4>;
----------------------------->8----------------------
in .dts files for ARC boards even in linux-next git tree.

-Alexey


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