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References: <20210304093139.471554-1-philippe.schenker@toradex.com>
In-Reply-To: <20210304093139.471554-1-philippe.schenker@toradex.com>
From:   Fabio Estevam <festevam@gmail.com>
Date:   Thu, 4 Mar 2021 08:24:54 -0300
Message-ID: <CAOMZO5COBmBc=3kHHWtftaRaAjgr0LkmvGrmTkQGZ_da-5_NFg@mail.gmail.com>
Subject: Re: [PATCH] ARM: dts: colibri-imx6ull: Change drive strength for usdhc2
To:     Philippe Schenker <philippe.schenker@toradex.com>
Cc:     "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>, NXP Linux Team <linux-imx@nxp.com>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Rob Herring <robh+dt@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Shawn Guo <shawnguo@kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
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Hi Philippe,

On Thu, Mar 4, 2021 at 6:31 AM Philippe Schenker
<philippe.schenker@toradex.com> wrote:
>
> The current setting reflects about 86 Ohms of source-impedance
> on the SDIO signals where the WiFi board is hooked up. PCB traces are
> routed with 50 Ohms impedance and there are no serial resistors on
> those traces.
>
> This commit changes the source-impedance to 52 Ohms to better match our
> hardware design.
>
> The impedances given in this commit message refer to 3.3V operation.
>
> Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>

Reviewed-by: Fabio Estevam <festevam@gmail.com>