linux-kernel - Re: [PATCH 2/2] phy: rockchip-emmc: try to get drive impedance from DT

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Message-ID: <CAD=FV=V0+=yknRQAZu98FVsbKnRTX_5beeKsLe01P0qT7gb5Zg@mail.gmail.com>
Date:   Thu, 5 Jan 2017 16:51:32 -0800
From:   Doug Anderson <dianders@...omium.org>
To:     Shawn Lin <shawn.lin@...k-chips.com>
Cc:     Kishon Vijay Abraham I <kishon@...com>,
        Rob Herring <robh+dt@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        Heiko Stuebner <heiko@...ech.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] phy: rockchip-emmc: try to get drive impedance from DT

Hi,

On Thu, Jan 5, 2017 at 1:31 AM, Shawn Lin <shawn.lin@...k-chips.com> wrote:
> Try to get drive impedance from DT and use it, otherwise
> use 50ohm by default in order not to break the existing boards
> as 50ohm works fine for them already.
>
> Signed-off-by: Shawn Lin <shawn.lin@...k-chips.com>
> ---
>
>  drivers/phy/phy-rockchip-emmc.c | 29 ++++++++++++++++++++++++++++-
>  1 file changed, 28 insertions(+), 1 deletion(-)

I could have sworn that you somehow needed to make sure that the eMMC
part itself needed to also be updated to be told the matching drive
impedance so you don't get a mismatch.  How do you make that work?
...or am I just confused.  I meant to try to dig more, but ran out of
time today.  :(

-Doug