Re: [Letux-kernel] [PATCH v5 3/5] misc serdev: Add w2sg0004 (gps receiver) power control driver

[H. Nikolaus Schaller]

Hi Johan,

> Am 27.02.2018 um 08:04 schrieb Johan Hovold <johan@xxxxxxxxxx>:
> 
> On Mon, Feb 12, 2018 at 04:26:18PM +0100, Pavel Machek wrote:
>> Hi!
>> 
>>>> Let's restart this discussion and focus on the main roadblock (others
>>>> are minor details which can be sorted out later).
>>>> 
>>>> If it feels like a hack, the key issue seems to me to be the choice of
>>>> the API to present the GPS data to user space. Right?
>>> 
>>> Or even more fundamentally, does this belong in the kernel at all?
>> 
>> Yes, it does.

Thanks, Pavel for supporting our view.

> 
> But not necessarily in its current form.

Is this a "yes after some code fixes"?

Pavel mentioned an example where such an evolutionary approach was taken.

> 
>>> Now, if we'd ever have a proper GPS framework that handled everything in
>>> kernel space (i.e. no more gpsd) then we would be able to write kernel
>>> drivers that also take care of PM. But perhaps that's unlikely to ever
>>> be realised given the state of things (proprietary protocols, numerous
>>> quirky implementations, etc).
>> 
>> That is what needs to happen.
>> 
>>> The kernel is probably not the place to be working around issues like
>>> that, even if serdev at least allows for such hacks to be fairly
>>> isolated in drivers (unlike some of the earlier proposals touching core
>>> code).
>> 
>> Oh, kernel is indeed right place to provide hardware abstraction --
>> and that includes bug workarounds.
> 
> Right, at least when such hacks can be confined to a driver and not be
> spread all over the place.

It seems that you forgot that the driver we propose is not spread all over
the place. It *is* confined to a single driver thanks to the serdev api.

BR and thanks,
Nikolaus