linux-kernel - Re: [PATCH 2/4] ARM: dts: exynos: Fix LAN9730 on Odroid U3 after tftpboot

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Date:   Mon, 9 Jan 2017 13:17:38 -0300
From:   Javier Martinez Canillas <javier@....samsung.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>,
        Kukjin Kim <kgene@...nel.org>,
        Anand Moon <linux.amoon@...il.com>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>,
        Peter Chen <peter.chen@....com>, gregkh@...uxfoundation.org,
        stern@...land.harvard.edu, ulf.hansson@...aro.org,
        broonie@...nel.org, sre@...nel.org, robh+dt@...nel.org,
        linux-usb@...r.kernel.org, linux-pm@...r.kernel.org,
        hverkuil@...all.nl, Markus Reichl <m.reichl@...etechno.de>
Subject: Re: [PATCH 2/4] ARM: dts: exynos: Fix LAN9730 on Odroid U3 after
 tftpboot

Hello Krzysztof,

On 01/07/2017 05:52 AM, Krzysztof Kozlowski wrote:
> The ethernet adapter LAN9730, after enabling in bootloader (e.g. for
> tftpboot) requires reset during boot.  Otherwise it won't come up.
> 
> The schematics of Odroid U3 are detailed enough but after grabbing
> knowledge also from other sources (like U-Boot) the overall design looks
> like:
> 1. LAN9730 is connected to HSIC0 and USB3503 to HSIC1 of EHCI controller.
> 2. USB3503 comes with its own reset pin: gpx3-5.
> 3. Reset pin of LAN9730 is pulled up to 3.3 V so it cannot be used.
> 4. The supply of 3.3 V for LAN9730 is delivered from buck8.
> 5. Buck8 state is a logical OR of registry value (through I2C command)
>    and ENB8 pin.  The ENB8, not described in schematics, is in fact
>    gpa1-1.
> 6. Missing or wrongly timed reset of LAN9730 might result in missing of
>    two devices: LAN9730 and USB3503. Without reset, LAN9730 will not
>    come up, if it was enabled by bootloader.
> 
> To fix the issue use the generic power sequence driver and toggle the
> ENB8 (buck8) pin.  Reset duration of 500 us was chosen by experiments
> (shortest working time was 400 us).  This is an easiest way to fix the
> long standing LAN9730 reset issue.
> 
> Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>
> ---

Thanks for keep pushing a fix for this long standing issue.

Reviewed-by: Javier Martinez Canillas <javier@....samsung.com>

Best regards,
-- 
Javier Martinez Canillas
Open Source Group
Samsung Research America