Re: [PATCH] i2c: designware-pci: fix autosuspend cleanup during teardown

[Andi Shyti <andi.shyti@kernel.org>]

Hi Guangshuo,

On Sun, Aug 09, 2026 at 03:30:55PM +0800, Guangshuo Li wrote:
> i2c_dw_pci_probe() calls pm_runtime_use_autosuspend(), but
> i2c_dw_pci_remove() does not call the matching
> pm_runtime_dont_use_autosuspend() during teardown.
> 
> If the autosuspend delay is set to a negative value while autosuspend
> is enabled, the runtime PM core increments usage_count to prevent
> runtime suspend. Without calling pm_runtime_dont_use_autosuspend()
> during teardown, this reference is not dropped.
> 
> The documentation for pm_runtime_use_autosuspend() also notes that it
> is important to undo it with pm_runtime_dont_use_autosuspend() at
> driver exit time, unless runtime PM was initially enabled with
> devm_pm_runtime_enable().
> 
> Add the missing pm_runtime_dont_use_autosuspend() call to the driver
> remove path.
> 
> This issue was found by manual code inspection.
> 
> Fixes: 18dbdda89f5c ("i2c-designware: Add runtime power management support")

This Fixes: is wrong because there was no autosuspend here. Maybe
you are referring to:

Fixes: 43452335224b ("i2c-designware: switch to use runtime PM autosuspend")
Cc: <stable@vger.kernel.org> # v3.10+

?

> Cc: stable@vger.kernel.org
> Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
> ---
>  drivers/i2c/busses/i2c-designware-pcidrv.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/i2c/busses/i2c-designware-pcidrv.c b/drivers/i2c/busses/i2c-designware-pcidrv.c
> index 468287922363..f1f4955f9a3f 100644
> --- a/drivers/i2c/busses/i2c-designware-pcidrv.c
> +++ b/drivers/i2c/busses/i2c-designware-pcidrv.c
> @@ -300,6 +300,7 @@ static void i2c_dw_pci_remove(struct pci_dev *pdev)
>  
>  	i2c_dw_disable(dev);
>  
> +	pm_runtime_dont_use_autosuspend(device);

If I haven't missed anything, pm_runtime_dont_use_autosuspend()
can drop the reference and trigger a suspend, which then calls
i2c_dw_runtime_suspend() and eventually i2c_dw_disable() for the
second time.

If this is correct, pm_runtime_dont_use_autosuspend() should be
moved towards the end, followed by i2c_dw_disable(), which would
then need to become the final cleanup step.

Intel folks need to verify the order anyway.

Thanks,
Andi

>  	pm_runtime_forbid(device);
>  	pm_runtime_get_noresume(device);
>  
> -- 
> 2.43.0
>