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

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

[Paul Cercueil]

The config0 register in the Xburst always reports a MIPS32r2
ISA, but not all of them support it.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 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

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

[Paul Burton]

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@crapouillou.net>
> ---
>  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

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

[Paul Cercueil]

Le mar. 7 mai 2019 à 23:15, Paul Burton <paul.burton@mips.com> a 
écrit :
> 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@crapouillou.net>
>>  ---
>>   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;

Smart!

> 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.

All the SoCs up to the jz4760 (included) have the D0 PRID and are 
MIPS32r1,
and the first one to use a different PRID is the jz4770 which is also 
the
first one which is MIPS32r2, so it works perfectly.

> Thanks,
>     Paul