linux-kernel - Re: [PATCH 3/4] perf/dwc_pcie: Always register for PCIe bus notifier

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Message-ID: <55303289-bb41-4e67-9912-4cf4335244ca@huawei.com>
Date: Thu, 15 Aug 2024 21:49:21 +0800
From: Yicong Yang <yangyicong@...wei.com>
To: Krishna chaitanya chundru <quic_krichai@...cinc.com>
CC: Shuai Xue <xueshuai@...ux.alibaba.com>, Jing Zhang
	<renyu.zj@...ux.alibaba.com>, Will Deacon <will@...nel.org>, Mark Rutland
	<mark.rutland@....com>, Baolin Wang <baolin.wang@...ux.alibaba.com>, Yicong
 Yang <yangyicong@...ilicon.com>, Jonathan Cameron
	<Jonathan.Cameron@...wei.com>, Jonathan Corbet <corbet@....net>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-arm-msm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-doc@...r.kernel.org>,
	<quic_vbadigan@...cinc.com>, <quic_nitegupt@...cinc.com>,
	<quic_skananth@...cinc.com>, <quic_ramkri@...cinc.com>,
	<quic_parass@...cinc.com>, <quic_mrana@...cinc.com>
Subject: Re: [PATCH 3/4] perf/dwc_pcie: Always register for PCIe bus notifier

On 2024/7/31 12:23, Krishna chaitanya chundru wrote:
> When the PCIe devices are discovered late, the driver can't find
> the PCIe devices and returns in the init without registering with
> the bus notifier. Due to that the devices which are discovered late
> the driver can't register for this.
> 
> Register for bus notifier even if the device is not found in init.
> 
> Fixes: af9597adc2f1 ("drivers/perf: add DesignWare PCIe PMU driver")
> Signed-off-by: Krishna chaitanya chundru <quic_krichai@...cinc.com>
> ---
>  drivers/perf/dwc_pcie_pmu.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/perf/dwc_pcie_pmu.c b/drivers/perf/dwc_pcie_pmu.c
> index c115348b8d53..aa1010b44bcb 100644
> --- a/drivers/perf/dwc_pcie_pmu.c
> +++ b/drivers/perf/dwc_pcie_pmu.c
> @@ -741,8 +741,6 @@ static int __init dwc_pcie_pmu_init(void)
>  
>  		found = true;
>  	}
> -	if (!found)
> -		return -ENODEV;
>  
>  	ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
>  				      "perf/dwc_pcie_pmu:online",
> @@ -753,9 +751,11 @@ static int __init dwc_pcie_pmu_init(void)
>  
>  	dwc_pcie_pmu_hp_state = ret;
>  
> -	ret = platform_driver_register(&dwc_pcie_pmu_driver);
> -	if (ret)
> -		goto platform_driver_register_err;
> +	if (!found) {
> +		ret = platform_driver_register(&dwc_pcie_pmu_driver);
> +		if (ret)
> +			goto platform_driver_register_err;
> +	}
> 

This doesn't match the commit.

If any device is found at this stage, we cannot use them since you don't
register a driver.

>  	ret = bus_register_notifier(&pci_bus_type, &dwc_pcie_pmu_nb);
>  	if (ret)
>