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

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Date:	Wed, 25 Jun 2014 07:42:20 +0200
From:	Marek Szyprowski <m.szyprowski@...sung.com>
To:	Kamil Debski <k.debski@...sung.com>,
	'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>, gautam.vivek@...sung.com
Subject: Re: [PATCH] phy: phy-samsung-usb2: Change phy power on/power off
 sequence

Hello,

On 2014-06-24 17:35, Kamil Debski wrote:
> 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.

My patch was a quick hack to get HSIC1 working. Kamil spent much more time
trying to figure out how the hardware actually behaves. Please drop my patch
and replace it with this one.

Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>

>
>> 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.

Thanks for investigating this issue! I will add this fix to next version
of Odroid patches.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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