linux-kernel - Re: [BISECTED] Allwinner A33 tablet does not fully power off

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Date:   Sun, 6 Nov 2022 09:15:40 +0200
From:   Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
To:     Samuel Holland <samuel@...lland.org>
Cc:     mripard@...nel.org, linux-sunxi@...ts.linux.dev,
        linux-kernel@...r.kernel.org, Merlijn Wajer <merlijn@...zup.org>,
        wens@...e.org
Subject: Re: [BISECTED] Allwinner A33 tablet does not fully power off



On 5.11.22 г. 21:18 ч., Samuel Holland wrote:
> On 11/5/22 03:23, Ivaylo Dimitrov wrote:
>> Hi Samuel,
>>
>> On 5.11.22 г. 4:21 ч., Samuel Holland wrote:
>>> Hi Ivo,
>>>
>>> On 10/29/22 10:23, Ivaylo Dimitrov wrote:
>>>> After commit 843107498f91e57d1d4b22cd8787112726fdaeb4 (bus: sunxi-rsb:
>>>> Implement suspend/resume/shutdown callbacks) Q8 A33 tablet I have here
>>>> cannot be powered-on after power-off, it needs press-and-hold of the
>>>> power button for 10 seconds (I guess some HW assisted power down
>>>> happens) before it can be powered-on again.
>>>>
>>>> The following patch makes it behave correctly:
>>>>
>>>> diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c
>>>> index 60b082fe2ed0..30016d62044c 100644
>>>> --- a/drivers/bus/sunxi-rsb.c
>>>> +++ b/drivers/bus/sunxi-rsb.c
>>>> @@ -818,10 +818,7 @@ static int sunxi_rsb_remove(struct platform_device
>>>> *pdev)
>>>>
>>>>    static void sunxi_rsb_shutdown(struct platform_device *pdev)
>>>>    {
>>>> -       struct sunxi_rsb *rsb = platform_get_drvdata(pdev);
>>>> -
>>>>           pm_runtime_disable(&pdev->dev);
>>>> -       sunxi_rsb_hw_exit(rsb);
>>>>    }
>>>>
>>>>    static const struct dev_pm_ops sunxi_rsb_dev_pm_ops = {
>>>>
>>>>
>>>> I guess the issue comes from the fact that by the time 'power off'
>>>> command to the power management IC has to be send, the bus it lives on
>>>> is already down, so the device is left in semi-powered down state. Ofc
>>>> this is a wild guess, however, preventing the bus being turned off on
>>>> shutdown fixes the issue.
>>>
>>> Your guess is correct. The controller gets shut down in
>>>
>>>     kernel_power_off()
>>>       kernel_shutdown_prepare()
>>>         device_shutdown()
>>>
>>> but the PMIC communication needs to happen later in
>>>
>>>     kernel_power_off()
>>>       machine_power_off()
>>>         pm_power_off()
>>>
>>>> Please LMK if the above is the correct approach so I will send a proper
>>>> patch or something else shall be fixed.
>>>
>>> Yes, this is exactly the right approach. The whole sunxi_rsb_shutdown()
>>
>> Don't we need pm_runtime_disable() on shutdown? As IIUC, the controller
>> might be suspended and we have to resume it to put it in state to accept
>> commands later on(in pm_power_off()).
> 
> sunxi_rsb_write() takes care of resuming the controller, so the
> controller being suspended prior to pm_power_off() is fine.
> pm_runtime_disable() would actually prevent resuming the controller
> later in sunxi_rsb_write().
> 

I see.

>>> function should be removed. When you send a patch, please add a Fixes:
>>> tag referencing the commit that you bisected to.
> 
> I found a couple of other issues as well, so I'll send out some fixes
> with you CC'd.
>

Ok, thanks. What about stable kernels, poweroff is broken since 
843107498f91e57d1d4b22cd8787112726fdaeb4?

Regards,
Ivo

> Regards,
> Samuel
>