Message-ID: <5148C4AB.1070502@wwwdotorg.org>
Date: Tue, 19 Mar 2013 14:03:55 -0600
From: Stephen Warren <swarren@wwwdotorg.org>
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To: Venu Byravarasu <vbyravarasu@nvidia.com>
CC: gregkh@linuxfoundation.org, stern@rowland.harvard.edu, balbi@ti.com,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-tegra@vger.kernel.org, devicetree-discuss@lists.ozlabs.org
Subject: Re: [PATCH 5/7] usb: phy: tegra: get ULPI reset GPIO info using DT.
References: <1363609781-4045-1-git-send-email-vbyravarasu@nvidia.com> <1363609781-4045-6-git-send-email-vbyravarasu@nvidia.com>
In-Reply-To: <1363609781-4045-6-git-send-email-vbyravarasu@nvidia.com>
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On 03/18/2013 06:29 AM, Venu Byravarasu wrote:
> As GPIO information is avail through DT, used it to get Tegra ULPI
> reset GPIO number. Added a new member to tegra_usb_phy structure to
> store this number.

> diff --git a/drivers/usb/phy/tegra_usb_phy.c b/drivers/usb/phy/tegra_usb_phy.c

> -	gpio_direction_output(config->reset_gpio, 0);
> +	gpio_direction_output(phy->reset_gpio, 0);
>  	msleep(5);
> -	gpio_direction_output(config->reset_gpio, 1);
> +	gpio_direction_output(phy->reset_gpio, 1);

That implies that the PHY reset signal is active-low. This should be
represented in the GPIO flags in the device tree. In other words,
instead of e.g.:

nvidia,phy-reset-gpio = <&gpio 169 0>; /* gpio PV1 */

you want:

nvidia,phy-reset-gpio = <&gpio 169 1>; /* gpio PV1 */

Flag 1 means active-low. See
Documentation/devicetree/bindings/gpio/nvidia,tegra20-gpio.txt. This is
a bug in the current device tree content, although it has no effect
since no code currently uses the GPIO flags from DT. I suggest creating
a separate patch to fix this, and inserting it between patch 1 and 2 of
the series.
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