Re: [Xen-devel] [PATCH v3 3/3] xen/arm: Introduce support for Renesas R-Car Gen2 platform

[Oleksandr Tyshchenko <oleksandr.tyshchenko@xxxxxxxxxxxxxxx>]

Hi, Ian.
Sorry for late response.

As I understood from
http://am.renesas.com/products/soc/assp/soc_pf/index.jsp
The "R-Mobile" and "R-Car" are the different platforms designed for
different areas.

The "R-Mobile" is a new integrated platform for mobile applications.
Integrated SH-Mobile, EMMA Mobile.
http://am.renesas.com/products/soc/assp/mobile/index.jsp

The "R-Car" is a new integrated platform for car information systems.
http://am.renesas.com/products/soc/assp/automotive/index.jsp

So, It seems that RCAR2 it is not a subset of shmobile.
Sure, they might have a lot in common, the same IP blocks, etc.
But I didn't investigate carefully how similar they are. And I can't
guarantee that they are similar enough to be a single platform in Xen.

Unfortunately, I have no glue why they all reside in
arch/arm/mach-shmobile in kernel.
Maybe for historical reasons.

I can only guarantee that uart stuff from this patch series should
works on all SoCs in R-Car Gen2 family.
At the same time the Iurii can guarantee that the board file he
introduced should be
suitable for R-Car Gen2 family.

For example, such a simple thing as a formula for calculating divider
value for uart baudrate can differs from one family to
another despite the fact that these families use the same UART IP
block named SCIF (clock may be differs - ext/int, another freq).
Or FIFO size, etc.
For second example, the R-Car Gen1, R-Mobile A1 based on ARM Cortex-A9
which is ARMv6, so it doesn't support
virt extensions at all. Also, there are many other SoCs for mobile
applications in R-Mobile/SH-Mobile series
based on non-ARM SoC. I think it would be worse to assign for the
platform in Xen another name than "RCAR2".
So, I would rename "SHMOBILE" for "RCAR2".

On Wed, Jan 28, 2015 at 6:16 PM, Andrii Anisov
<andrii.anisov@xxxxxxxxxxxxxxx> wrote:
> Hello Ian,
>
> When I discussed with Iurii Konovalenko about this naming during
> review I mentioned following the Linux kernel way.
>
> Shmobile within kernel is arm specific, not the same as arch/sh. In
> the kernel you would find arch/arm/mach-shmobile folder where
> Renesas'es R-CarX SoCs support reside. F.e. R8A7790 what is R-Car H2
> we have on our table. Browsing the kernel configs you will find
> shmobile not rcar as well.
>
> From other hand I do not like rcar2 naming for uart. I would prefer
> the IP block naming - scif.
>
> Andrii Anisov | Team Lead
> GlobalLogic
> Kyiv, 03038, Protasov Business Park, M.Grinchenka, 2/1
> P +38.044.492.9695x3664  M +380505738852  S andriyanisov
> www.globallogic.com
>
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>
> On Wed, Jan 28, 2015 at 4:16 PM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
>>
>> On Wed, 2015-01-28 at 15:48 +0200, Oleksandr Tyshchenko wrote:
>> > Hi Ian
>> >
>> > On Wed, Jan 28, 2015 at 3:26 PM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> 
>> > wrote:
>> > > On Fri, 2015-01-23 at 17:33 +0200, Oleksandr Tyshchenko wrote:
>> > >> From: Iurii Konovalenko <iurii.konovalenko@xxxxxxxxxxxxxxx>
>> > >>
>> > >> Signed-off-by: Iurii Konovalenko <iurii.konovalenko@xxxxxxxxxxxxxxx>
>> > >> Reviewed-by: Julien Grall <julien.grall@xxxxxxxxxx>
>> > >> ---
>> > >>  xen/arch/arm/platforms/Makefile   |  1 +
>> > >>  xen/arch/arm/platforms/shmobile.c | 71 
>> > >> +++++++++++++++++++++++++++++++++++++++
>> > >>  2 files changed, 72 insertions(+)
>> > >>  create mode 100644 xen/arch/arm/platforms/shmobile.c
>> > >>
>> > >> diff --git a/xen/arch/arm/platforms/Makefile 
>> > >> b/xen/arch/arm/platforms/Makefile
>> > >> index 8f47c16..29e931a 100644
>> > >> --- a/xen/arch/arm/platforms/Makefile
>> > >> +++ b/xen/arch/arm/platforms/Makefile
>> > >> @@ -4,5 +4,6 @@ obj-$(CONFIG_ARM_32) += exynos5.o
>> > >>  obj-$(CONFIG_ARM_32) += midway.o
>> > >>  obj-$(CONFIG_ARM_32) += omap5.o
>> > >>  obj-$(CONFIG_ARM_32) += sunxi.o
>> > >> +obj-$(CONFIG_ARM_32) += shmobile.o
>> > >
>> > > Everything else calls the platform rcar. How does shmobile relate to
>> > > that?
>> > Unfortunately, the author of this patch in vacation now.
>> >
>> > Perhaps Iurii took this name from kernel part 
>> > (Linux/arch/arm/mach-shmobile/...)
>> > where the arch specific things for this platform is located,
>> > especially the SMP and timer support.
>> >
>> > I would rename shmobile to rcar2.
>>
>> I'd prefer us to be consistent one way or another.
>>
>> Is RCAR2 a subset of shmobile or the other way around?
>>
>> http://am.renesas.com/applications/automotive/cis/cis_highend/rcar_h2/index.jsp
>>  doesn't mention shmobile at all.
>>
>> Having determined which is the "parent"/superset my next question would
>> be how similar are the various "children" -- similar enough to be a
>> single platform in Xen, or different enough that we will need multiple
>> platforms, since that would have an impact on which name I think we
>> should pick.
>>
>> (To some extent we can fidge this since we can always git mv stuff, but
>> we should at least give it our best guess up front)
>>
>>
>> Ian.
>>
>>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxx
>> http://lists.xen.org/xen-devel



-- 

Oleksandr Tyshchenko | Embedded Dev
GlobalLogic
www.globallogic.com

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