[PATCH 1/2] arm: rmobile: Add RZ/G2M SoC

[Biju Das]

Hi Marek,

Thanks for the feedback.

> Subject: Re: [PATCH 1/2] arm: rmobile: Add RZ/G2M SoC
>
> On 9/18/20 6:03 PM, Biju Das wrote:
> > Add CPU and PRR IDs for R8A774A1(a.k.a RZ/G2M) SoC.
>
> [...]
>
> > +static const struct udevice_id *of_soc_match_compatible(void) {
> > +const struct udevice_id *of_match = soc_ids;
> > +int i;
> > +
> > +for (i = 0; i < ARRAY_SIZE(soc_ids); i++) {
> > +if (!fdt_node_check_compatible(gd->fdt_blob, 0,
> > +       of_match->compatible))
> > +return of_match;
> > +of_match++;
> > +}
> > +
> > +return NULL;
> > +}
>
> This should rather be a generic function, I think this is something that already
> exists in Linux common code too, right ?

No.  I have seen some other SoC's uses similar logic [1]& [2] .

[1] https://elixir.bootlin.com/u-boot/v2020.10-rc4/source/board/samsung/common/exynos5-dt-types.c#L246
[2] https://elixir.bootlin.com/u-boot/v2020.10-rc4/source/arch/arm/mach-uniphier/boards.c#L156


> >  static int rmobile_cpuinfo_idx(void)
> >  {
> >  int i = 0;
> >  u32 cpu_type = rmobile_get_cpu_type();
> > +const struct udevice_id *match = of_soc_match_compatible();
> >
> > +/*
> > + * This loop identifies CPU based on PRR register, it differentiates
> > + * RZ/G SoC's from R-Car SoC's by matching RZ/G SoC compatible
> string
> > + * from DT against the family_type.
> > + */
> >  for (; i < ARRAY_SIZE(rmobile_cpuinfo); i++)
> > -if (rmobile_cpuinfo[i].cpu_type == cpu_type)
> > -break;
> > +if (rmobile_cpuinfo[i].cpu_type == cpu_type) {
> > +if (match &&
> > +    rmobile_cpuinfo[i].family_type == match->data)
> > +break;
> > +else if (!match &&
> > + rmobile_cpuinfo[i].family_type !=
> SOC_RZG2)
> > +break;
> > +}
>
> I still don't understand this, so if cpu_type ==
> RMOBILE_CPU_TYPE_R8A7796 , then it can be either RZG2 or R8A7796, right?

Yep you are right.

> And there is no PRR bit or any other bit to tell those two chips apart ?
No. Currently only way you can distinguish is by SoC compatible string and family type.
See [3] for SoC identification logic used to differentiate  RCar and RZ/G2
[3]:- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/soc/renesas/renesas-soc.c?h=v5.9-rc5#n311

> I would like to avoid using the OF match here, because that fails if you use
> MULTI_DTB_FIT , does it not ?

No. It works OK on both RZ/G2SoC's[4] and RCar[5]

[4]  MULTI_DTB_FIT logs for RZG2[HMN] boards

CPU: Renesas Electronics R8A774E1 rev 3.0
Model: HopeRun HiHope RZ/G2H with sub board
DRAM:  3.9 GiB

CPU: Renesas Electronics R8A774A1 rev 1.3
Model: HopeRun HiHope RZ/G2M with sub board
DRAM:  3.9 GiB

CPU: Renesas Electronics R8A774B1 rev 1.1
Model: HopeRun HiHope RZ/G2N with sub board
DRAM:  3.9 GiB

[5] u-boot based on R-Car M3N using rcar3_salvator-x_defconfig,  it reports proper SoC.

CPU: Renesas Electronics R8A77965 rev 1.1
Model: Renesas Salvator-XS board based on r8a77965
DRAM: 1.9 GiB
Bank #0: 0x048000000 - 0x0bfffffff, 1.9 GiB

MMC: sd at ee100000: 0, sd at ee140000: 1, sd at ee160000: 2
Loading Environment from MMC... OK
In: serial at e6e88000
Out: serial at e6e88000
Err: serial at e6e88000
Net: eth0: ethernet at e6800000
Hit any key to stop autoboot: 0
=>

 So can you please check whether there might
> be some way to tell the two SoCs apart ?

At present there is no way other than matching the SoC compatible string.

Cheers,
Biju


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