linux-kernel - Re: [PATCH] drivers/perf: hisi: Fix readl DDRC

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Message-ID: <4c0097dd-6dd3-e4e6-14d1-d94a6d98bf5a@huawei.com>
Date: Thu, 17 Oct 2024 14:39:53 +0800
From: Yicong Yang <yangyicong@...wei.com>
To: Youwan Wang <youwan@...china.com>
CC: <jonathan.cameron@...wei.com>, <yangyicong@...ilicon.com>,
	<will@...nel.org>, <mark.rutland@....com>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drivers/perf: hisi: Fix readl DDRC_VERSION stuck

On 2024/10/10 16:42, Youwan Wang wrote:
> The CPU of the device I am using is kunpeng 920,
> which can start normally with version 5.4 kernel.
> However, when installing version 6.6 kernel, the
> kernel gets stuck when loading the "hisi_dddrc_pmu"
> driver. I went to debug and found that it gets stuck
> when "readl (ddrc_pmu ->base+DDRC_VERSION)". I suspect

what does "stuck" mean here? do you see some hardware errors
or similiar? If so this should be an unexpected device and
your patch still doesn't address the issue, since you only make
the probe work but the device's still inaccessible so it
shouldn't be appeared in the system.

as Will mentions, this is probably a firmware issue. please
try to update to the latest firmware.

Thanks.

> that the hardware does not support it. My modification is:
> for the "HISI0233" device, according to the implementation
> of version 5.4 kernel, the identity is not obtained from
> the register. For "identifier" sysfs, identifier: 0
> 
> Signed-off-by: Youwan Wang <youwan@...china.com>
> ---
>  drivers/perf/hisilicon/hisi_uncore_ddrc_pmu.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/perf/hisilicon/hisi_uncore_ddrc_pmu.c b/drivers/perf/hisilicon/hisi_uncore_ddrc_pmu.c
> index b804e3738113..3cecad46b01f 100644
> --- a/drivers/perf/hisilicon/hisi_uncore_ddrc_pmu.c
> +++ b/drivers/perf/hisilicon/hisi_uncore_ddrc_pmu.c
> @@ -321,6 +321,9 @@ static int hisi_ddrc_pmu_init_data(struct platform_device *pdev,
>  		return PTR_ERR(ddrc_pmu->base);
>  	}
>  
> +	if (strstr(pdev->name, "HISI0233"))
> +		return 0;
> +
>  	ddrc_pmu->identifier = readl(ddrc_pmu->base + DDRC_VERSION);
>  	if (ddrc_pmu->identifier >= HISI_PMU_V2) {
>  		if (device_property_read_u32(&pdev->dev, "hisilicon,sub-id",
>