RE: [PATCH v3 1/2] usb: ohci-at91: Forcibly suspend ports while USB suspend

Yang, Wenyou
2016-06-10T08:59:13Z

Hi Alan,

> -----Original Message-----
> From: Alan Stern [mailto:stern@rowland.harvard.edu]
> Sent: 2016年6月9日 3:14
> To: Yang, Wenyou <Wenyou.Yang@atmel.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>; Ferre, Nicolas
> <Nicolas.FERRE@atmel.com>; Rob Herring <robh+dt@kernel.org>; Pawel Moll
> <pawel.moll@arm.com>; Mark Brown <broonie@kernel.org>; Ian Campbell
> <ijc+devicetree@hellion.org.uk>; Kumar Gala <galak@codeaurora.org>;
> Alexandre Belloni <alexandre.belloni@free-electrons.com>; Kernel development
> list <linux-kernel@vger.kernel.org>; devicetree@vger.kernel.org; linux-arm-
> kernel@lists.infradead.org; USB list <linux-usb@vger.kernel.org>
> Subject: Re: [PATCH v3 1/2] usb: ohci-at91: Forcibly suspend ports while USB
> suspend
>
> On Wed, 8 Jun 2016, Wenyou Yang wrote:
>
> > In order to the save power consumption, as a workaround, suspend
> > forcibly the USB PORTA/B/C via set the SUSPEND_A/B/C bits of OHCI
> > Interrupt Configuration Register in the SFRs while OHCI USB suspend.
> >
> > This suspend operation must be done before the USB clock is disabled,
> > resume after the USB clock is enabled.
> >
> > Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
> > ---
>
> You never answered the questions I posted for the first version of this
> patch:
>
> What does this mean? What does suspending a port do? Is it the same as a
> normal USB port suspend?
>
> If it is the same, why doesn't the USB_PORT_FEAT_SUSPEND subcase of the
> SetPortFeature case in ohci_hub_control() already take care of this?

I remembered I answered your questions, http://lists.infradead.org/pipermail/linux-arm-kernel/2016-May/429245.html

Maybe not very clear.

>
> Alan Stern

Best Regards,
Wenyou Yang