Messages in this thread | | | Date | Fri, 4 Nov 2022 21:21:23 -0500 | From | Samuel Holland <> | Subject | Re: [BISECTED] Allwinner A33 tablet does not fully power off |
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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() function should be removed. When you send a patch, please add a Fixes: tag referencing the commit that you bisected to.
Regards, Samuel
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