Re: [PATCH] MIPS: jz4740: Fix Ingenic SoCs sometimes reporting wrong ISA

From: Paul Burton
Date: Tue May 07 2019 - 17:16:36 EST


Hi Paul,

On Tue, May 07, 2019 at 09:41:01PM +0200, Paul Cercueil wrote:
> The config0 register in the Xburst always reports a MIPS32r2
> ISA, but not all of them support it.
>
> Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> ---
> arch/mips/jz4740/setup.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/arch/mips/jz4740/setup.c b/arch/mips/jz4740/setup.c
> index 7e63c54eb8d2..2508c026bdfa 100644
> --- a/arch/mips/jz4740/setup.c
> +++ b/arch/mips/jz4740/setup.c
> @@ -64,6 +64,7 @@ static unsigned long __init get_board_mach_type(const void *fdt)
>
> void __init plat_mem_setup(void)
> {
> + struct cpuinfo_mips *c = &current_cpu_data;
> int offset;
> void *dtb;
>
> @@ -81,6 +82,18 @@ void __init plat_mem_setup(void)
> jz4740_detect_mem();
>
> mips_machtype = get_board_mach_type(dtb);
> +
> + switch (mips_machtype) {
> + case MACH_INGENIC_JZ4740:
> + /*
> + * The config0 register in the Xburst always reports a MIPS32r2
> + * ISA, but not all of them support it.
> + */
> + c->isa_level &= ~MIPS_CPU_ISA_M32R2;
> + break;
> + default:
> + break;
> + }
> }
>
> void __init device_tree_init(void)
> --
> 2.21.0.593.g511ec345e18

Would it work to check the PRID instead? That way we could keep the CPU
probing in cpu-probe.c, for example something like this in
cpu_probe_ingenic():

if ((c->processor_id & PRID_COMP_MASK) == PRID_COMP_INGENIC_D0)
c->isa_level &= ~MIPS_CPU_ISA_M32R2;

That relies on the D0 PRID always being MIPS32r1 & other PRIDs always
being MIPS32r2 though - do you know whether that's the case? Our
comments in asm/cpu.h mapping the various PRIDs to SoCs suggests this
would be OK to me.

Thanks,
Paul