From: "Heiko Stübner" <heiko@sntech.de>
To: Shawn Lin <shawn.lin@rock-chips.com>
Cc: Kishon Vijay Abraham I <kishon@ti.com>,
Rob Herring <robh+dt@kernel.org>,
devicetree@vger.kernel.org, linux-rockchip@lists.infradead.org,
Douglas Anderson <dianders@chromium.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] Documentation: phy: introduce new optional property to specify drive impedance
Date: Thu, 05 Jan 2017 12:15:18 +0100 [thread overview]
Message-ID: <11505388.Y1Yzh8HsIT@diego> (raw)
In-Reply-To: <1483608682-226716-1-git-send-email-shawn.lin@rock-chips.com>
Hi Shawn,
Am Donnerstag, 5. Januar 2017, 17:31:21 schrieb Shawn Lin:
> We need to modify the drive impedance according to the
> different hardware condition. So let's expose this to
> the DT.
>
> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
> ---
>
> Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt
> b/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt index
> e3ea557..731aeb9 100644
> --- a/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt
> +++ b/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt
> @@ -14,6 +14,11 @@ specified by name:
> access to it), it is strongly suggested.
> - clocks: Should have a phandle to the card clock exported by the SDHCI
> driver.
>
> +Optional Properties:
> +- drive_impedance: Must be one of 33, 40, 50, 66, 100. This property allows
> + different boards to specify their own drive impedance depending on the
> + hardware condition.
In what unit are your 33, 40 etc values?
It is recommended that properties should specify their unit, see all the
properties ending in "-ma", "-ns" and so on and also
Documentation/devicetree/bindings/property-units.txt
Also properties should use dashes ("-") not underscores.
Judging by the second patch, these are Ohm, so combining the above you
probably want
drive-impedance-ohms
as property name.
Also the patch subject is slightly misleading and should probably specify the
rockchip-emmc as well :-)
Heiko
next prev parent reply other threads:[~2017-01-05 11:52 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-05 9:31 [PATCH 1/2] Documentation: phy: introduce new optional property to specify drive impedance Shawn Lin
2017-01-05 9:31 ` [PATCH 2/2] phy: rockchip-emmc: try to get drive impedance from DT Shawn Lin
2017-01-06 0:51 ` Doug Anderson
2017-01-06 1:09 ` Shawn Lin
2017-01-06 18:29 ` Doug Anderson
2017-01-05 11:15 ` Heiko Stübner [this message]
2017-01-06 0:44 ` [PATCH 1/2] Documentation: phy: introduce new optional property to specify drive impedance Shawn Lin
2017-01-09 18:06 ` Rob Herring
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