Re: [PATCH v2] cpufreq: qcom-hw: drop devm_xxx() calls from init/exit hooks

[Shawn Guo <shawn.guo@linaro.org>]

On Tue, Jan 19, 2021 at 10:39:25AM +0800, Shawn Guo wrote:
> Commit f17b3e44320b ("cpufreq: qcom-hw: Use
> devm_platform_ioremap_resource() to simplify code") introduces
> a regression on platforms using the driver, by failing to initialise
> a policy, when one is created post hotplug.
> 
> When all the CPUs of a policy are hoptplugged out, the call to .exit()
> and later to devm_iounmap() does not release the memory region that was
> requested during devm_platform_ioremap_resource().  Therefore,
> a subsequent call to .init() will result in the following error, which
> will prevent a new policy to be initialised:
> 
> [ 3395.915416] CPU4: shutdown
> [ 3395.938185] psci: CPU4 killed (polled 0 ms)
> [ 3399.071424] CPU5: shutdown
> [ 3399.094316] psci: CPU5 killed (polled 0 ms)
> [ 3402.139358] CPU6: shutdown
> [ 3402.161705] psci: CPU6 killed (polled 0 ms)
> [ 3404.742939] CPU7: shutdown
> [ 3404.765592] psci: CPU7 killed (polled 0 ms)
> [ 3411.492274] Detected VIPT I-cache on CPU4
> [ 3411.492337] GICv3: CPU4: found redistributor 400 region 0:0x0000000017ae0000
> [ 3411.492448] CPU4: Booted secondary processor 0x0000000400 [0x516f802d]
> [ 3411.503654] qcom-cpufreq-hw 17d43000.cpufreq: can't request region for resource [mem 0x17d45800-0x17d46bff]
> 
> With that being said, the original code was tricky and skipping memory
> region request intentionally to hide this issue.  The true cause is that
> those devm_xxx() device managed functions shouldn't be used for cpufreq
> init/exit hooks, because &pdev->dev is alive across the hooks and will
> not trigger auto resource free-up.  Let's drop the use of device managed
> functions and manually allocate/free resources, so that the issue can be
> fixed properly.
> 
> Fixes: f17b3e44320b ("cpufreq: qcom-hw: Use devm_platform_ioremap_resource() to simplify code")
> Suggested-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

Hi Viresh,

What happened on this patch?  I thought we would have it in 5.11
release, but ...

Shawn