linux-kernel - Re: [PATCH v2] perf: RISC-V: fix IRQ detection on T-Head C908

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Message-ID: <20240318-spoilage-drastic-d58a16c8b9f3@spud>
Date: Mon, 18 Mar 2024 11:43:19 +0000
From: Conor Dooley <conor@...nel.org>
To: Qingfang Deng <dqfext@...il.com>
Cc: Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Atish Patra <atishp@...shpatra.org>,
	Anup Patel <anup@...infault.org>, Will Deacon <will@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Andrew Jones <ajones@...tanamicro.com>,
	Conor Dooley <conor.dooley@...rochip.com>,
	Heiko Stuebner <heiko@...ech.de>, linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Qingfang Deng <qingfang.deng@...lower.com.cn>
Subject: Re: [PATCH v2] perf: RISC-V: fix IRQ detection on T-Head C908

On Mon, Mar 18, 2024 at 06:02:40PM +0800, Qingfang Deng wrote:
> From: Qingfang Deng <qingfang.deng@...lower.com.cn>
> 
> T-Head C908 has the same IRQ num and CSR as previous C9xx cores, but
> reports non-zero marchid and mimpid. Add the check for C908 ID.
> 
> Fixes: 65e9fb081877 ("drivers/perf: riscv_pmu_sbi: add support for PMU variant on T-Head C9xx cores")
> Signed-off-by: Qingfang Deng <qingfang.deng@...lower.com.cn>
> ---
> v2: add C908 ID check

If you read the replies to v1 in full, you would see I objected there to
this approach and made suggestions as to how I would like it done:
https://lore.kernel.org/linux-riscv/IA1PR20MB4953CEBE4CB6AC7238849353BB282@IA1PR20MB4953.namprd20.prod.outlook.com/

I don't want to see an expansion of these ID checks.

Thanks,
Conor.
> 
>  arch/riscv/errata/thead/errata.c       | 5 +++--
>  arch/riscv/include/asm/vendorid_list.h | 2 ++
>  drivers/perf/riscv_pmu_sbi.c           | 6 ++++--
>  3 files changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c
> index b1c410bbc1ae..da3b34866d8f 100644
> --- a/arch/riscv/errata/thead/errata.c
> +++ b/arch/riscv/errata/thead/errata.c
> @@ -125,8 +125,9 @@ static bool errata_probe_pmu(unsigned int stage,
>  	if (!IS_ENABLED(CONFIG_ERRATA_THEAD_PMU))
>  		return false;
>  
> -	/* target-c9xx cores report arch_id and impid as 0 */
> -	if (arch_id != 0 || impid != 0)
> +	/* Early c9xx cores report arch_id and impid as 0 */
> +	if (!((arch_id == 0 && impid == 0) ||
> +	      (arch_id == THEAD_C908_ARCH_ID && impid == THEAD_C908_IMP_ID)))
>  		return false;
>  
>  	if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
> diff --git a/arch/riscv/include/asm/vendorid_list.h b/arch/riscv/include/asm/vendorid_list.h
> index 2f2bb0c84f9a..57b3de510d38 100644
> --- a/arch/riscv/include/asm/vendorid_list.h
> +++ b/arch/riscv/include/asm/vendorid_list.h
> @@ -8,5 +8,7 @@
>  #define ANDES_VENDOR_ID		0x31e
>  #define SIFIVE_VENDOR_ID	0x489
>  #define THEAD_VENDOR_ID		0x5b7
> +#define  THEAD_C908_ARCH_ID	0x8000000009140d00
> +#define  THEAD_C908_IMP_ID	0x8a000
>  
>  #endif
> diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
> index bbd6fe021b3a..34d8689982de 100644
> --- a/drivers/perf/riscv_pmu_sbi.c
> +++ b/drivers/perf/riscv_pmu_sbi.c
> @@ -833,8 +833,10 @@ static int pmu_sbi_setup_irqs(struct riscv_pmu *pmu, struct platform_device *pde
>  		riscv_pmu_use_irq = true;
>  	} else if (IS_ENABLED(CONFIG_ERRATA_THEAD_PMU) &&
>  		   riscv_cached_mvendorid(0) == THEAD_VENDOR_ID &&
> -		   riscv_cached_marchid(0) == 0 &&
> -		   riscv_cached_mimpid(0) == 0) {
> +		   ((riscv_cached_marchid(0) == 0 &&
> +		     riscv_cached_mimpid(0) == 0) ||
> +		    (riscv_cached_marchid(0) == THEAD_C908_ARCH_ID &&
> +		     riscv_cached_mimpid(0) == THEAD_C908_IMP_ID))) {
>  		riscv_pmu_irq_num = THEAD_C9XX_RV_IRQ_PMU;
>  		riscv_pmu_use_irq = true;
>  	} else if (riscv_isa_extension_available(NULL, XANDESPMU) &&
> -- 
> 2.34.1
> 
> 

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