Re: [PATCHv3] w1: omap-hdq: Simplify driver with PM runtime autosuspend

[H. Nikolaus Schaller]

> Am 17.04.2020 um 16:43 schrieb Andreas Kemnade <andreas@xxxxxxxxxxxx>:
> 
> On Fri, 17 Apr 2020 16:22:47 +0200
> "H. Nikolaus Schaller" <hns@xxxxxxxxxxxxx> wrote:
> 
>>> Am 16.04.2020 um 20:46 schrieb Tony Lindgren <tony@xxxxxxxxxxx>:
>>> 
>>> * H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> [200416 15:04]:  
>>>> Hi Tony,
>>>> it looks as if something with this patch is broken on GTA04. For v5.6 and v5.7-rc1.
>>>> 
>>>> HDQ battery access times out after ca. 15 seconds and I get temperature of -273.1ÂC...
>>>> 
>>>> Reverting this patch and everything is ok again.  
>>> 
>>> Hmm OK interesting.
>>> 
>>>> What is "ti,mode" about? Do we have that (indirectly) in gta04.dtsi?
>>>> Or does this patch need some CONFIGs we do not happen to have?  
>>> 
>>> Sounds like you have things working though so there should be no
>>> need for having ti,mode = "1w" in the dts.
>>> 
>>>>> 	pm_runtime_enable(&pdev->dev);
>>>>> +	pm_runtime_use_autosuspend(&pdev->dev);
>>>>> +	pm_runtime_set_autosuspend_delay(&pdev->dev, 300);  
>>> 
>>> Care to check if changing pm_runtime_set_autosuspend_delay value
>>> to -1 in probe makes the issue go away? Or change it manually
>>> to -1 via sysfs.
>>> 
>>> If that helps, likely we have a missing pm_runtime_get_sync()
>>> somewhere in the driver.  
>> 
>> Yes, it does! It suffices to set it to -1 for one readout.
>> Aything else I can test?
>> 
> How does it depend on loaded drivers?
> Is it really mainline kernel + config + devicetree or something else?

Well, I can revert the patch on the same
kernel (5.6 or 5.7-rc1) + config + devicetree + user-space
and the problem is gone.

This means that something is different between the old and the new
version which makes the hdq access delayed and failing. Of course I
don't know the reason for it and what does influence it.

> 
> Can you reproduce the problem with init=/bin/bash
> and then mount sysfs and modprobe omap_hdq?

I am not sure how quickly I can test such a setup.

> Regarding pm_runtime stuff I thought I have the worst case scenario.

What may make a difference is the sequence in which drivers are loaded.

BR,
Nikolaus