[Letux-kernel] power management problems in ehci-omap

H. Nikolaus Schaller hns at goldelico.com
Sun Feb 4 14:43:31 CET 2018


Hi,
Andreas seems to be travelling back from FOSDEM so I jump in with best of my knowledge.

> Am 04.02.2018 um 12:34 schrieb Michael Nazzareno Trimarchi <michael at amarulasolutions.com>:
> 
> Hi
> 
> On Sun, Feb 4, 2018 at 12:07 PM, H. Nikolaus Schaller <hns at goldelico.com> wrote:
>> Hi Michael,
>> 
>>> Am 04.02.2018 um 11:55 schrieb Michael Nazzareno Trimarchi <michael at amarulasolutions.com>:
>>> 
>>> Hi Andreas
>>> 
>>> On Sun, Feb 4, 2018 at 11:50 AM, Andreas Kemnade <andreas at kemnade.info> wrote:
>>>> Hi,
>>>> 
>>>> On Sun, 4 Feb 2018 09:43:45 +0100
>>>> Michael Nazzareno Trimarchi <michael at amarulasolutions.com> wrote:
>>>> 
>>>>> Hi Andreas
>>>>> 
>>>>> On Sun, Feb 4, 2018 at 9:38 AM, Andreas Kemnade <andreas at kemnade.info> wrote:
>>>>>> On Sun, 4 Feb 2018 00:10:50 +0100
>>>>>> Michael Nazzareno Trimarchi <michael at amarulasolutions.com> wrote:
>>>>>> 
>>>>>>> Hi
>>>>>>> 
>>>>>>> On Sun, Feb 4, 2018 at 12:03 AM, Andreas Kemnade <andreas at kemnade.info> wrote:
>>>>>>>> Hi,
>>>>>>>> 
>>>>>>>> I booted a 4.15 kernel without udev and loaded modules piece by piece to analyze
>>>>>>>> pm problems. modprobe ehci-omap increases current by around 35mA and
>>>>>>>> also rmmod ehci-omap does not let it go down at all.
>>>>>>>> 
>>>>>>>> I expect that removing hardware does the same thing
>>>>>> nonsense sentence from me, was to tired. I would expect that removing the modules
>>>>>> properly powers down the device.
>>>>>>>> 
>>>>>>>> Also suspend current increases by around 15mA if that module is loaded.
>>>>>>>> I tested with having everything disabled which is attached to that usb bus.
>>>>>>>> 
>>>>>>> 
>>>>>>> Do you have an LTE connected to the usb?
>>>>>>> 
>>>>>> Yes, there is a UMTS modem attached, but it was off during the tests.
>>>>>> It did not enumerate on the modem.
>>>>>> 
>>>>> 
>>>>> Just to understand if the suspend current drop was connected to the
>>>>> suspend of lte modem on your side.
>>>>> So you don't have anything connected on usb bus?
>>>>> 
>>>> Suspend current is increased when the ehci-omap module is loaded
>>>> in comparison to the state. I tested with the modem disabled, so there
>>>> is nothing on the bus. Increased suspend current is one thing,
>>>> current_before_modprobe_ehci_omap != current_after_rmmod_ehci_omap.
>>>> 
>>>> I am testing with init=some_testscript.sh, so no userspace
>>>> is doing strange things. No module autoload or something.
>>>> 
>>> 
>>> How many port are configured and how is the phy part connected to the
>>> ehci controller?
>>> Can you point me the schematic page?
>> 
>> it is essentially a copy&paste from BeagleBoard XM.
>> 
>> Schematics of the GTA04 are here:
>> 
>>        http://projects.goldelico.com/p/gta04-main/downloads/48/
>> 
>> USB PHY is on page 9.
>> 
> 
> I see. GPIO174 is controlled by you during boot or connected to the dts?
> I don't find in mainline the connection to the physical and it's own
> programming.
> Can you check if the phy is in reset when module is remove?

The reset gpio is defined in the respective board-DTS:

https://elixir.free-electrons.com/linux/v4.15/source/arch/arm/boot/dts/omap3-beagle-xm.dts#L88
https://elixir.free-electrons.com/linux/v4.15/source/arch/arm/boot/dts/omap3-gta04.dtsi#L120

BR,
Nikolaus



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