Re: USB driver support for high current charging

2015-02-27 Thread Greg KH 
On Fri, Feb 27, 2015 at 08:48:40AM +, Schmid, Carsten wrote:
> I have had a look into the spec (USB PD), but it does not explicitly
> explain whether the negotiation is done in hardware (by dedicated
> charger chips) or driver software (which then assigns higher allowed
> current to the ports).
> 
> We are planning for new devices to be designed, where we want to
> support charging smartphones etc. and we want to know if there has to
> be done something for this in the USB drivers, and from which kernel
> on the PD will be supported.
> Actually it seems that the negotiation is a job for the charger chips
> and they signal their state via GPIOs to CPU/SoC.

How are the GPIOs defined?  How is the CPU supposed to know where they
are?  Through ACPI?

> However, I think that the USB team should have an eye on the USB PD
> spec. and keep it in mind.

The USB-IF has been actively hostile toward Linux and the Linux
community, going out of their way to make things difficult for us, so
keeping track of their new specifications is very low on my priority
list.

thanks,

greg k-h
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RE: USB driver support for high current charging

2015-02-27 Thread Schmid, Carsten 
I have had a look into the spec (USB PD), but it does not explicitly explain 
whether the negotiation is done in hardware (by dedicated charger chips) or 
driver software (which then assigns higher allowed current to the ports).

We are planning for new devices to be designed, where we want to support 
charging smartphones etc. and we want to know if there has to be done something 
for this in the USB drivers, and from which kernel on the PD will be supported.
Actually it seems that the negotiation is a job for the charger chips and they 
signal their state via GPIOs to CPU/SoC.

However, I think that the USB team should have an eye on the USB PD spec. and 
keep it in mind.

Thanks,
Carsten



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> -Original Message-
> From: Greg KH [mailto:gre...@linuxfoundation.org]
> Sent: Mittwoch, 25. Februar 2015 16:45
> To: Schmid, Carsten
> Cc: linux-usb@vger.kernel.org
> Subject: Re: USB driver support for high current charging
> 
> On Wed, Feb 25, 2015 at 08:39:49AM +, Schmid, Carsten wrote:
> > Hello,
> >
> > there is a spec from USB regarding high current charging (on top of USB3.0).
> > Do you know if there is any driver support required, and if so, when
> > will this be available with Linux?
> 
> I think the spec will answer the "is any driver support required"
> question, right?  Have you looked at it?
> 
> Do you have hardware with this feature that needs Linux support?
> 
> thanks,
> 
> greg k-h
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Re: USB driver support for high current charging

2015-02-25 Thread Greg KH 
On Wed, Feb 25, 2015 at 08:39:49AM +, Schmid, Carsten wrote:
> Hello,
> 
> there is a spec from USB regarding high current charging (on top of USB3.0).
> Do you know if there is any driver support required, and if so, when
> will this be available with Linux?

I think the spec will answer the "is any driver support required"
question, right?  Have you looked at it?

Do you have hardware with this feature that needs Linux support?

thanks,

greg k-h
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