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Date:   Fri, 15 Jul 2022 12:05:09 -0700
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Subject: Re: [RESEND PATCH v2 2/3] drivers/perf: add DDR Sub-System Driveway
 PMU driver for Yitian 710 SoC
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To:     Shuai Xue <xueshuai@linux.alibaba.com>,
        Jonathan.Cameron@Huawei.com, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, will@kernel.org, mark.rutland@arm.com
Cc:     baolin.wang@linux.alibaba.com, yaohongbo@linux.alibaba.com,
        nengchen@linux.alibaba.com, zhuo.song@linux.alibaba.com
References: <20220617111825.92911-1-xueshuai@linux.alibaba.com>
 <20220715151310.90091-3-xueshuai@linux.alibaba.com>
From:   Randy Dunlap <rdunlap@infradead.org>
In-Reply-To: <20220715151310.90091-3-xueshuai@linux.alibaba.com>
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Hi--

On 7/15/22 08:13, Shuai Xue wrote:
> Add the DDR Sub-System Driveway Performance Monitoring Unit (PMU) driver
> support for Alibaba T-Head Yitian 710 SoC chip. Yitian supports DDR5/4
> DRAM and targets cloud computing and HPC.
> 
> Each PMU is registered as a device in /sys/bus/event_source/devices, and
> users can select event to monitor in each sub-channel, independently. For
> example, ali_drw_21000 and ali_drw_21080 are two PMU devices for two
> sub-channels of the same channel in die 0. And the PMU device of die 1 is
> prefixed with ali_drw_400XXXXX, e.g. ali_drw_40021000.
> 
> Due to hardware limitation, one of DDRSS Driveway PMU overflow interrupt
> shares the same irq number with MPAM ERR_IRQ. To register DDRSS PMU and
> MPAM drivers successfully, add IRQF_SHARED flag.
> 
> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
> Co-developed-by: Hongbo Yao <yaohongbo@linux.alibaba.com>
> Signed-off-by: Hongbo Yao <yaohongbo@linux.alibaba.com>
> Co-developed-by: Neng Chen <nengchen@linux.alibaba.com>
> Signed-off-by: Neng Chen <nengchen@linux.alibaba.com>
> ---
>  drivers/perf/Kconfig                  |   8 +
>  drivers/perf/Makefile                 |   1 +
>  drivers/perf/alibaba_uncore_drw_pmu.c | 793 ++++++++++++++++++++++++++
>  3 files changed, 802 insertions(+)
>  create mode 100644 drivers/perf/alibaba_uncore_drw_pmu.c
> 
> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> index 1e2d69453771..dfafba4cb066 100644
> --- a/drivers/perf/Kconfig
> +++ b/drivers/perf/Kconfig
> @@ -183,6 +183,14 @@ config APPLE_M1_CPU_PMU
>  	  Provides support for the non-architectural CPU PMUs present on
>  	  the Apple M1 SoCs and derivatives.
>  
> +config ALIBABA_UNCORE_DRW_PMU
> +	tristate "Alibaba T-Head Yitian 710 DDR Sub-system Driveway PMU driver"
> +	depends on (ARM64 && ACPI)
> +	default m

Why should this driver be automatically built?
I.e., why is the "default m" here at all?

Thanks.

> +	help
> +	  Support for Driveway PMU events monitoring on Yitian 710 DDR
> +	  Sub-system.


-- 
~Randy