[PATCH 1/2] of: addr: Abort address translation for parent nodes missing 'ranges'

[Dario Binacchi]

Hi Bin,

> Il 17/03/2021 02:26 Bin Meng <bmeng.cn at gmail.com> ha scritto:
> 
>  
> Hi Dario,
> 
> On Wed, Mar 17, 2021 at 4:57 AM Dario Binacchi <dariobin at libero.it> wrote:
> >
> > Hi Bin,
> >
> > > Il 16/03/2021 02:28 Bin Meng <bmeng.cn at gmail.com> ha scritto:
> > >
> > >
> > > Hi Dario,
> > >
> > > On Tue, Mar 16, 2021 at 6:49 AM Dario Binacchi <dariobin at libero.it> wrote:
> > > >
> > > >
> > > > > Il 15/03/2021 19:23 Simon Glass <sjg at chromium.org> ha scritto:
> > > > >
> > > > >
> > > > > +Tom Rini too
> > > > >
> > > > >
> > > > > On Tue, 16 Mar 2021 at 03:48, Bin Meng <bmeng.cn at gmail.com> wrote:
> > > > > >
> > > > > > +Dario Binacchi
> > > > > >
> > > > > > On Mon, Mar 15, 2021 at 3:11 PM Simon Glass <sjg at chromium.org> wrote:
> > > > > > >
> > > > > > > Hi Bin,
> > > > > > >
> > > > > > > On Wed, 3 Mar 2021 at 14:54, Simon Glass <sjg at chromium.org> wrote:
> > > > > > > >
> > > > > > > > On Fri, 26 Feb 2021 at 00:36, Bin Meng <bmeng.cn at gmail.com> wrote:
> > > > > > > > >
> > > > > > > > > The implementation of of_translate_one() was taken from the one in
> > > > > > > > > Linux kernel drivers/of/address.c, and the Linux one added a quirk
> > > > > > > > > for Apple Macs that don't have the <ranges> property in the parent
> > > > > > > > > node. Since U-Boot does not support Apple Macs, remove the comment
> > > > > > > > > block and adhere to the spec to abort the translation.
> > > > > > > > >
> > > > > > > > > Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
> > > > > > > > > ---
> > > > > > > > >
> > > > > > > > >  drivers/core/of_addr.c | 24 ++++++------------------
> > > > > > > > >  1 file changed, 6 insertions(+), 18 deletions(-)
> > > > > > > >
> > > > > > > > Reviewed-by: Simon Glass <sjg at chromium.org>
> > > > > > >
> > > > > > > Unfortunately this seems to cause a test failure for
> > > > > > > ut_dm_fdt_translation. Can you please take a look?
> > > > > >
> > > > > > It seems the no "ranges" property was intentionally removed by the
> > > > > > following commit:
> > > > > >
> > > > > > commit d64b9cdcd475eb7f07b49741ded87e24dae4a5fc
> > > > > > Author: Dario Binacchi <dariobin at libero.it>
> > > > > > Date:   Wed Dec 30 00:16:21 2020 +0100
> > > > > >
> > > > > >     fdt: translate address if #size-cells = <0>
> > > > > >
> > > > > >     The __of_translate_address routine translates an address from the
> > > > > >     device tree into a CPU physical address. A note in the description of
> > > > > >     the routine explains that the crossing of any level with
> > > > > >     since inherited from IBM. This does not happen for Texas Instruments, or
> > > > > >     at least for the beaglebone device tree. Without this patch, in fact,
> > > > > >     the translation into physical addresses of the registers contained in the
> > > > > >     am33xx-clocks.dtsi nodes would not be possible. They all have a parent
> > > > > >     with #size-cells = <0>.
> > > > > >
> > > > > > It looks the commit was needed for beaglebone board.
> > > > > >
> > > > > > Dario, could you please comment on why U-Boot needs to done like this,
> > > > > > while Linux kernel has this check? Is the beaglebone board not working
> > > > > > in Linux?
> > > > > >
> > > >
> > > > Beaglebone is working in Linux, but I think Linux walks the device tree less
> > > > fully than u-boot.
> > > > I was surprised by the address translation error when traversing nodes with
> > > > size cells 0. And for this reason I added the CONFIG_OF_TRANSLATE_ZERO_SIZE_CELLS
> > > > symbol to fix the issue, not enabled by default, thus making the change backwards
> > > > compatible.
> > >
> > > Could you please prepare a patch against upstream Linux kernel, so
> > > that U-Boot can be in sync with it?
> >
> > With pleasure. But how do I justify the patch since it doesn't fix any bugs?
> > Can I refer to the patches developed for U-boot?
> 
> Good question :)
> 
> If Linux does not have any issue, maybe U-Boot's fix is questionable?
> 
> Maybe the beagleboard needs to use another API to decode the address?
> What API is used in Linux?

I'll do some checking, although I think the Linux device binding / probing flow 
is more complex than u-boot.

Thanks and regards,
Dario

> 
> Regards,
> Bin