Re: [PATCH v3 09/12] EXAMPLE CODE: usb: port: Parse pwrseq phandle from Device Tree

From	Peter Chen <hzpeterchen@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3 09/12] EXAMPLE CODE: usb: port: Parse pwrseq phandle from Device Tree
Date	2016-06-01 14:20 +0200
Message-ID	<rFdhT-8iE-9@gated-at.bofh.it> (permalink)
References	<rF9nX-5Ug-7@gated-at.bofh.it> <rF9nX-5Ug-15@gated-at.bofh.it> <rFaan-6aY-43@gated-at.bofh.it>
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On Wed, Jun 01, 2016 at 01:57:23AM -0700, Stephen Boyd wrote:
> Quoting Krzysztof Kozlowski (2016-06-01 01:02:18)
> > Parse usb-pwrseq property from Device Tree to get the phandle to pwrseq
> > device.  The pwrseq device will be used by USB hub to cycle the power
> > before activating ports.
> > 
> > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
> 
> Drive by review comment.
> 
> I was hoping this would help me with a problem I'm having where I have a
> hub (smsc4604) that needs to be taken out of reset before my HSIC
> controller sends a USB reset to it, but it seems this is more about
> doing some sort of power on sequence after enumeration?
> 

No, you may need to do reset before enumeration, the general purpose of
reset is eliminate unstable hardware state, and let the controller find
the device.

Try to do it at bootloader to see if it works for you.

-- 

Best Regards,
Peter Chen

Thread

[PATCH v3 09/12] EXAMPLE CODE: usb: port: Parse pwrseq phandle from  Device Tree Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2016-06-01 10:10 +0200
  Re: [PATCH v3 09/12] EXAMPLE CODE: usb: port: Parse pwrseq phandle from  Device Tree Stephen Boyd <stephen.boyd@linaro.org> - 2016-06-01 11:00 +0200
    Re: [PATCH v3 09/12] EXAMPLE CODE: usb: port: Parse pwrseq phandle  from Device Tree Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2016-06-01 11:10 +0200
    Re: [PATCH v3 09/12] EXAMPLE CODE: usb: port: Parse pwrseq phandle  from Device Tree Peter Chen <hzpeterchen@gmail.com> - 2016-06-01 14:20 +0200
      Re: [PATCH v3 09/12] EXAMPLE CODE: usb: port: Parse pwrseq phandle from  Device Tree Stephen Boyd <stephen.boyd@linaro.org> - 2016-06-01 20:20 +0200
        Re: [PATCH v3 09/12] EXAMPLE CODE: usb: port: Parse pwrseq phandle  from Device Tree Peter Chen <hzpeterchen@gmail.com> - 2016-06-02 03:40 +0200

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