On 06/15/2018 12:37 PM, Ulrich Hecht wrote:
> On Fri, Jun 15, 2018 at 12:09 PM, Marek Vasut <marek.vasut@xxxxxxxxx> wrote:
>>> + arm_smccc_smc(ARM_SMCCC_RENESAS_MEMCONF,
>>> + 0, 0, 0, 0, 0, 0, 0, &res);
>>
>> Will this call work on platforms without patched ATF ?
>> (I think not, don't you need to handle return value?)
>
> I have not actually tested that, but if I understand the ATF code
> correctly, unimplemented calls return
> SMC_UNK (0xffffffff), which should be handled by the default case (NOP) below.
Which means the board has a memory size of 0 and fails to boot ?
>>> + switch (res.a0) {
>>> + case 1:
>>> + base[0] = 0x048000000ULL;
>>> + size[0] = 0x038000000ULL;
>>> + base[1] = 0x500000000ULL;
>>> + size[1] = 0x040000000ULL;
>>> + base[2] = 0x600000000ULL;
>>> + size[2] = 0x040000000ULL;
>>> + base[3] = 0x700000000ULL;
>>> + size[3] = 0x040000000ULL;
>>> + fdt_fixup_memory_banks(blob, base, size, 4);
>>> + break;
>>> + case 2:
>>> + base[0] = 0x048000000ULL;
>>> + size[0] = 0x078000000ULL;
>>> + base[1] = 0x500000000ULL;
>>> + size[1] = 0x080000000ULL;
>>> + fdt_fixup_memory_banks(blob, base, size, 2);
>>> + break;
>>> + case 3:
>>> + base[0] = 0x048000000ULL;
>>> + size[0] = 0x078000000ULL;
>>> + base[1] = 0x500000000ULL;
>>> + size[1] = 0x080000000ULL;
>>> + base[2] = 0x600000000ULL;
>>> + size[2] = 0x080000000ULL;
>>> + base[3] = 0x700000000ULL;
>>> + size[3] = 0x080000000ULL;
>>> + fdt_fixup_memory_banks(blob, base, size, 4);
>>> + break;
>>
>> Obvious design question is -- since you're adding new SMC call anyway,
>> can't the call just return the memory layout table itself, so that it
>> won't be duplicated both in U-Boot and ATF ?
>
> My gut feeling was to go with the smallest interface possible.
But this doesn't scale. The API here uses some ad-hoc constants to
identify memory layout tables which have to be encoded both in ATF and
U-Boot, both of which must be kept in sync.
The ATF already has those memory layout tables, it's only a matter of
passing them to U-Boot. If you do just that, the ad-hoc constants and
encoding of tables into U-Boot goes away and in fact simplifies the design.
Yet, I have to wonder if ATF doesn't already contain some sort of
standard SMC call to get memory topology. It surprises me that it wouldn't.
--
Best regards,
Marek Vasut
