linux-kernel - Re: [PATCH] MIPS: Ingenic: Disable HPTLB for D0 XBurst CPUs too

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Date:   Mon, 14 Dec 2020 03:12:23 +0800
From:   Zhou Yanjie <zhouyanjie@...yeetech.com>
To:     Paul Cercueil <paul@...pouillou.net>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc:     Zhou Yanjie <zhouyanjie@...o.com>, od@...c.me,
        linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH] MIPS: Ingenic: Disable HPTLB for D0 XBurst CPUs too

Hi Paul,

On 2020/12/12 上午8:03, Paul Cercueil wrote:
> The JZ4760 has the HPTLB as well, but has a XBurst CPU with a D0 CPUID.
>
> Disable the HPTLB for all XBurst CPUs with a D0 CPUID. In the case where
> there is no HPTLB (e.g. for older SoCs), this won't have any side
> effect.
>
> Fixes: b02efeb05699 ("MIPS: Ingenic: Disable abandoned HPTLB function.")
> Cc: <stable@...r.kernel.org> # 5.4
> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
> ---
>   arch/mips/kernel/cpu-probe.c | 15 ++++++++-------
>   1 file changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
> index e6853697a056..31cb9199197c 100644
> --- a/arch/mips/kernel/cpu-probe.c
> +++ b/arch/mips/kernel/cpu-probe.c
> @@ -1830,16 +1830,17 @@ static inline void cpu_probe_ingenic(struct cpuinfo_mips *c, unsigned int cpu)
>   		 */
>   		case PRID_COMP_INGENIC_D0:
>   			c->isa_level &= ~MIPS_CPU_ISA_M32R2;
> -			break;
> +			fallthrough;
>   
>   		/*
>   		 * The config0 register in the XBurst CPUs with a processor ID of
> -		 * PRID_COMP_INGENIC_D1 has an abandoned huge page tlb mode, this
> -		 * mode is not compatible with the MIPS standard, it will cause
> -		 * tlbmiss and into an infinite loop (line 21 in the tlb-funcs.S)
> -		 * when starting the init process. After chip reset, the default
> -		 * is HPTLB mode, Write 0xa9000000 to cp0 register 5 sel 4 to


I just noticed that I mistakenly wrote a capital 'W' in the original 
version.

with that fixed:

Reviewed-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@...yeetech.com>


BTW: Are you planning to add support for JZ4760 recently? I am currently 
writing the CGU driver for JZ4775 and X2000. If you plan to add support 
for JZ4760, I can also write the CGU driver for JZ4760 by the way.


Thanks and best regards!


> -		 * switch back to VTLB mode to prevent getting stuck.
> +		 * PRID_COMP_INGENIC_D0 or PRID_COMP_INGENIC_D1 has an abandoned
> +		 * huge page tlb mode, this mode is not compatible with the MIPS
> +		 * standard, it will cause tlbmiss and into an infinite loop
> +		 * (line 21 in the tlb-funcs.S) when starting the init process.
> +		 * After chip reset, the default is HPTLB mode, Write 0xa9000000
> +		 * to cp0 register 5 sel 4 to switch back to VTLB mode to prevent
> +		 * getting stuck.
>   		 */
>   		case PRID_COMP_INGENIC_D1:
>   			write_c0_page_ctrl(XBURST_PAGECTRL_HPTLB_DIS);