linux-kernel - Re: [PATCH v1 1/1] cpufreq: mediatek-hw: Fix double devm

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Message-ID: <20211102034822.diil2tgggpppf4ma@vireshk-i7>
Date:   Tue, 2 Nov 2021 09:18:22 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Hector Yuan <hector.yuan@...iatek.com>
Cc:     linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        linux-kernel@...r.kernel.org, wsd_upstream@...iatek.com
Subject: Re: [PATCH v1 1/1] cpufreq: mediatek-hw: Fix double devm_remap in
 hotplug case

On 29-10-21, 19:42, Hector Yuan wrote:
> From: "Hector.Yuan" <hector.yuan@...iatek.com>
> 
> When hotpluging policy cpu, cpu policy init will be called multiple times.
> Unplug CPU7 -> CPU6 -> CPU5 -> CPU4, then plug CPU4 again.
> In this case, devm_remap will double remap and resource allocate fail.
> So replace devm_remap to ioremap and release resources in cpu policy exit.
> 
> Signed-off-by: Hector.Yuan <hector.yuan@...iatek.com>
> ---
>  drivers/cpufreq/mediatek-cpufreq-hw.c |   33 ++++++++++++++++++++++++++++++---
>  1 file changed, 30 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/cpufreq/mediatek-cpufreq-hw.c b/drivers/cpufreq/mediatek-cpufreq-hw.c
> index 0cf18dd..25317d7 100644
> --- a/drivers/cpufreq/mediatek-cpufreq-hw.c
> +++ b/drivers/cpufreq/mediatek-cpufreq-hw.c
> @@ -36,6 +36,8 @@ enum {
>  struct mtk_cpufreq_data {
>  	struct cpufreq_frequency_table *table;
>  	void __iomem *reg_bases[REG_ARRAY_SIZE];
> +	struct resource *res;
> +	void __iomem *base;
>  	int nr_opp;
>  };
>  
> @@ -156,6 +158,7 @@ static int mtk_cpu_resources_init(struct platform_device *pdev,

pdev specific initializations shouldn't be done from policy->init(),
but instead do those only once from mtk_cpufreq_hw_driver_probe().

That way such bugs won't occur again.

-- 
viresh