linux-kernel - Re: [PATCH 4/9] drivers/perf: hisi: Use ACPI driver

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Message-ID: <20250301064347.GB27700@willie-the-truck>
Date: Sat, 1 Mar 2025 06:43:49 +0000
From: Will Deacon <will@...nel.org>
To: Yicong Yang <yangyicong@...wei.com>
Cc: mark.rutland@....com, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, jonathan.cameron@...wei.com,
	prime.zeng@...ilicon.com, linuxarm@...wei.com,
	yangyicong@...ilicon.com, wangyushan12@...wei.com
Subject: Re: [PATCH 4/9] drivers/perf: hisi: Use ACPI driver_data to retrieve
 SLLC PMU information

On Tue, Feb 18, 2025 at 05:19:55PM +0800, Yicong Yang wrote:
> From: Junhao He <hejunhao3@...wei.com>
> 
> Make use of struct acpi_device_id::driver_data for version specific
> information rather than judge the version register. This will help
> to simplify the probe process and also a bit easier for extension.
> 
> Factor out SLLC register definition to struct hisi_sllc_pmu_regs.
> No functional changes intended.
> 
> Signed-off-by: Junhao He <hejunhao3@...wei.com>
> Signed-off-by: Yicong Yang <yangyicong@...ilicon.com>
> ---
>  drivers/perf/hisilicon/hisi_uncore_sllc_pmu.c | 191 ++++++++++++------
>  1 file changed, 125 insertions(+), 66 deletions(-)
> 
> diff --git a/drivers/perf/hisilicon/hisi_uncore_sllc_pmu.c b/drivers/perf/hisilicon/hisi_uncore_sllc_pmu.c
> index dbd079016fc4..c1fd60d397c3 100644
> --- a/drivers/perf/hisilicon/hisi_uncore_sllc_pmu.c
> +++ b/drivers/perf/hisilicon/hisi_uncore_sllc_pmu.c
> @@ -36,11 +36,14 @@
>  #define SLLC_SRCID_NONE			0x0
>  #define SLLC_TGTID_EN			BIT(5)
>  #define SLLC_TGTID_NONE			0x0
> -#define SLLC_TGTID_MIN_SHIFT		1
> -#define SLLC_TGTID_MAX_SHIFT		12
> -#define SLLC_SRCID_CMD_SHIFT		1
> -#define SLLC_SRCID_MSK_SHIFT		12
> +#define SLLC_TGTID_MIN_MSK		GENMASK(11, 1)
> +#define SLLC_TGTID_MAX_MSK		GENMASK(22, 12)
> +#define SLLC_SRCID_CMD_MSK		GENMASK(11, 1)
> +#define SLLC_SRCID_MSK_MSK		GENMASK(22, 12)
>  #define SLLC_NR_EVENTS			0x80
> +#define SLLC_EVENT_CNTn(cnt0, n)	((cnt0) + (n) * 8)
> +#define SLLC_FIRST_BIT(_mask)		(find_first_bit((const unsigned long *)&(_mask), 32))
> +#define SLLC_FIELD_PREP(_mask, _val)	(_mask & (_val << SLLC_FIRST_BIT(_mask)))

It's a bit of a shame to have to compute this dynamically given that the
input mask is constant for a given device. Is it not possible to use the
generic FIELD_PREP macro in per-device code and then just dispatch to
that, instead of funneling everything through hisi_sllc_pmu_regs?

Will