在2024年5月8日五月 下午1:50，Serge Semin写道：
> On Tue, May 07, 2024 at 10:01:51AM +0100, Jiaxun Yang wrote:
>> Move mips_cm_probe after prom_init so we can use fdt functions
>> in mips_cm_probe to obtain essential information.
>>
>> Impat for all systems that may have CM in system:
>
>> - geneirc: Adjusted code to accommodate this change
>
> s/geneirc/generic
>
>> - Lantiq: No impact, CM configuration won't be changed at all
>> - ralink: Called mips_cm_probe on it's own, in prom_init->prom_soc_init
>
>> - malta: No impact, CM address comes from CP0_CMGCR
>
> Are you sure about this? This was one of the problematic part I met
> back when was trying to implement the feature.
> arch/mips/mti-malta/malta-init.c:
> prom_init()
> +-> mips_cpc_probe()
> +-> mips_cpc_phys_base()
> +-> mips_cm_present(): mips_gcr_base != NULL
> +-> read_gcr_cpc_status()
> +-> read_gcr_cpc_base()
> +-> write_gcr_cpc_base()
>
> So by moving mips_cm_probe() to being executed after prom_init() the
> calls-chain above will be broken since the mips_gcr_base will be left
> uninitialized. Do I miss something?
Hi Serge,
Good catch! This is indeed a problem.
I tried to dig a little bit and found that a possible solution is to
move SMP initialization to device_tree_init(), as what generic platform
did.
I was able to test malta boot with this solution on my heavily patched
QEMU, I can confirm that both CM-SMP and scache are working as expected.
Will share my QEMU patches and configurations in next rev.
Thanks
- Jiaxun
>
> Please, note originally the mips_cm_probe() invocation was right
> above the Malta's mips_cpc_probe():
> 3af5a67c86a3 ("MIPS: Fix early CM probing")
>
> -Serge(y)
>
>>
>> Signed-off-by: Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx>
>> ---
>> arch/mips/kernel/setup.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
>> index 12a1a4ffb602..732579c8f4f8 100644
>> --- a/arch/mips/kernel/setup.c
>> +++ b/arch/mips/kernel/setup.c
>> @@ -773,8 +773,8 @@ static void __init setup_rng_seed(void)
>> void __init setup_arch(char **cmdline_p)
>> {
>> cpu_probe();
>> - mips_cm_probe();
>> prom_init();
>> + mips_cm_probe();
>>
>> setup_early_fdc_console();
>> #ifdef CONFIG_EARLY_PRINTK
>>
>> --
>> 2.34.1
>>
>>
--
- Jiaxun
