Hi Marek,
Thanks for the feedback.
Subject: Re: [PATCH 1/2] arm: rmobile: Add RZ/G2M SoC
On 9/19/20 1:37 PM, Biju Das wrote: [...]
+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] .
I mean, this looks like Linux's soc_device_match() , so such a function is likely generic code, there is nothing platform specific to it, is there ?
I agree, we need to have a new generic api for such purpose. The Linux/U-boot soc_device_match is for adding quirks with in different ES version of same SoC.
What we here need is similar to of_match_compatible for array of different SoC's. Can you please confirm [1] drivers/soc/soc-uclass.c is the right place for such generic api?
[1] https://elixir.bootlin.com/u-boot/v2020.10-rc4/source/drivers/soc/soc-uclass...
[1] https://elixir.bootlin.com/u-boot/v2020.10-rc4/source/board/samsung/co mmon/exynos5-dt-types.c#L246 [2] https://elixir.bootlin.com/u-boot/v2020.10-rc4/source/arch/arm/mach-un iphier/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/tre e/drivers/soc/renesas/renesas-soc.c?h=v5.9-rc5#n311
So Linux is matching on the compatible string of DT passed from U-Boot , right ? Linux has it easier then.
But where does U-Boot get that compatible string from, in case there are multiple DTs passed to U-Boot and U-Boot needs to find out on which SoC it is running on ?
Maybe you can pass the compatible from TFA, which is already happening.
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@ee100000: 0, sd@ee140000: 1, sd@ee160000: 2 Loading Environment from MMC... OK In: serial@e6e88000 Out: serial@e6e88000 Err: serial@e6e88000 Net: eth0: ethernet@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.
Thinking about it a bit more, if you were to use the compatible string psssed from TFA in the / node, you could iterate over soc_ids[] array and return RMOBILE_CPU_TYPE_x , which could be stored there as .data . Then you won't even need the SOC_RZG2 and it would all be faster, as all you would need is a single pass over a smaller array.
Good point. Ok will get rid of SOC_RZG2, will use smaller array forRZG2.
Are you suggesting to modify "arch_misc_init" directly set "platform" environment variable using match logic, which use a smaller array Compared to rmobile_cpuinfo.
Basically we match the compatible string from TFA, .data from " RMOBILE_CPU_TYPE_x" matched against PRR values and set the platform type .
Cheers, Biju
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