linux-kernel - RE: [PATCH] phy: phy-samsung-usb2: Change phy power on/power off sequence

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Message-id: <074a01cf8fc1$e906f0c0$bb14d240$%debski@samsung.com>
Date:	Tue, 24 Jun 2014 17:35:20 +0200
From:	Kamil Debski <k.debski@...sung.com>
To:	'Daniel Drake' <drake@...lessm.com>
Cc:	linux-kernel@...r.kernel.org,
	'linux-samsung-soc' <linux-samsung-soc@...r.kernel.org>,
	linux-usb@...r.kernel.org, kishon@...com,
	Tomasz Figa <t.figa@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	gautam.vivek@...sung.com
Subject: RE: [PATCH] phy: phy-samsung-usb2: Change phy power on/power off
 sequence

Hi Daniel,

> From: Daniel Drake [mailto:drake@...lessm.com]
> Sent: Tuesday, June 24, 2014 5:09 PM
> 
> On Tue, Jun 24, 2014 at 1:54 PM, Kamil Debski <k.debski@...sung.com>
> wrote:
> > The Exynos4412 USB 2.0 PHY hardware differs from the description
> > provided in the documentation. Some register bits have different
> > function. This patch fixes the defines of register bits and changes
> > the way how phys are powered on and off.
> 
> I guess this replaces the patch titled "drivers: phy: exynos4x12-phy:
> fix HSIC1 power on/off sequence"

Yes, indeed it replaces this patch. I did some more research on how the
hardware actually behaves.

> 
> Tested on ODROID-U2. Seems to be working as well as the previous patch:

Thank you very much for testing.

> - Internal SMSC hub works on boot and after reboot, tested with USB
> mouse
> - Internal SMSC ethernet device works on boot, but disappears upon
> reboot. (same as previous patch, also reproduced by Marek)

By reboot I guess that you mean typing "reboot" or by using SysRq magic
and not power cycling?

If so, I had experienced the same symptoms. I guess that the Ethernet
chip is not reset properly and fails to enumerate without power cycling
(it's nRESET pin is connected to P3V3).

I found that removing regulator-always-on from buck8_reg: BUCK8 in the
dts file fixes this problem.

Best wishes,
-- 
Kamil Debski
Samsung R&D Institute Poland


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