[Letux-kernel] Fwd: mmc PM regression

[H. Nikolaus Schaller]

Hi,

Am 08.02.2016 um 20:27 schrieb Andreas Kemnade <andreas at kemnade.info>:

> On Mon, 8 Feb 2016 11:18:23 +0100
> "H. Nikolaus Schaller" <hns at goldelico.com> wrote:
> 
>> Hi,
>> 
>>> Am 07.02.2016 um 22:22 schrieb Andreas Kemnade <andreas at kemnade.info>:
>>> 
>>> Hi Nikolaus,
>>> 
>>> On Sun, 7 Feb 2016 10:53:38 +0100
>>> "H. Nikolaus Schaller" <hns at goldelico.com> wrote:
>>> 
>>>> Hi Andreas,
>>>> 
>>>>> Am 07.02.2016 um 10:06 schrieb Andreas Kemnade <andreas at kemnade.info>:
>>>>> 
>>>>> Hi Nikolaus,
>>>>> 
>>>>> On Fri, 5 Feb 2016 19:30:27 +0100
>>>>> "H. Nikolaus Schaller" <hns at goldelico.com> wrote:
>>>>> 
>>>>>>> &mmc2 {
>>>>>>>     vmmc-supply = <&vaux4>;
>>>>>>>     bus-width = <4>;
>>>>>>>     ti,non-removable;
>>>>>>>     cap-power-off-card;     /* remove! */ <----
>>>>>>> };
>>>>>>> What about the "remove!" here? What are the plans/ideas/problems here?  
>>>>>> 
>>>>>> I don't know.
>>>>>> 
>>>>> If I understand that correctly, then that is about what to do with vaux4.
>>>>> Thats why I asked my question below.
>>>>> 
>>>>>>> Was it once enabled and caused problems?
>>>>>>> 277acf4b545327104c9b779eec7c440285d11a39
>>>>>>> looks like that.  
>>>>>> 
>>>>>> That is heritage from Neil nobody else was able to understand so far...
>>>>>> 
>>>>>>> 
>>>>>>> Is the idea to never switch off vaux4? At least everything
>>>>>>> regarding sdio suspend/remove/resume should be tested in both ways  
>>>>>> 
>>>>>> No, vaux4 must be turned off if we neither need WLAN nor BT.
>>>>>> 
>>>>> It should. But *must* it be turned off?
>>>> 
>>>> Yes. It is also shared with the Bluetooth side... So if you keep the WLAN
>>>> running we will also have ~50mA for bluetooth.
>>>> 
>>> BT seems to have quite good power saving.
>>> I have booted 4.5rc2 with init=/bin/bash
>>> loading modules, ifconfig wlan0 up (no connection), 
>>> hciattach, hciconfig hci0 up
>>> and running l2ping gives 90mA total consumption, around 80mA without l2ping.
>> 
>> Well, Bluetooth in total has not a big consumption. I think <50mA.
>> 
>> But 10mA is a lot...
>> 
> I would guess that 10mA without l2ping running is like 40% wifi, 40% bt and
> the rest soc/glue.
> 
>>> 
>>>>> Are there any other reason besides saving a few mA (which is of course
>>>>> important)?
>>>> 
>>>> Very important, and more important than everything else...
>>>> 
>>> That does not answer my question. 
>> 
>> Maybe I can't answer it because I have not written that code...
>> 
> I think we have misunderstood each other. 
> 
> I did understand your "Vaux4 *must* be turned off if bt+wifi is not used"
> like "you cannot expect that the system runs stable under that condition"

Ah, no. If it is not used, there are simply no commands exchanged... But
they can stay powered on - if you ignore power saving...

> 
> I do not see a reason for that so I ask you as a board designer for reasons.
> 
> And you probably have talked about your expression what a good kernel should
> do: perfect powersaving.

Yes... This is our main concern. I.e. the biggest missing feature of the GTA04.
And it is software driven.

BR,
Nikolaus