From: Simon Horman <horms+renesas@verge.net.au>
To: Geert Uytterhoeven <geert+renesas@glider.be>,
linux-renesas-soc@vger.kernel.org
Cc: Andrew Lunn <andrew@lunn.ch>,
Simon Horman <horms+renesas@verge.net.au>,
Magnus Damm <magnus.damm@gmail.com>,
linux-arm-kernel@lists.infradead.org,
Wolfram Sang <wsa@the-dreams.de>
Subject: [PATCH/RFC repost] arm64: dts: renesas: ebisu, draak: Limit EtherAVB to 100Mbps
Date: Wed, 17 Jul 2019 14:57:39 +0200 [thread overview]
Message-ID: <20190717125739.21450-1-horms+renesas@verge.net.au> (raw)
* According to the R-Car Gen3 Hardware Manual Errata for Rev 1.00 of
August 24, 2018, the TX clock internal delay mode isn't supported
on R-Car E3 (r8a77990) and D3 (r8a77995).
* TX clock internal delay mode is required for reliable 1Gbps communication
using the KSZ9031RNX phy present on the Ebisu and Draak boards.
Thus, the E3 based Ebisu and D3 based Draak boards reliably use 1Gbps and
the speed should be limited to 100Mbps.
Based on work by Kazuya Mizuguchi.
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
---
This is a repost of this change.
In earlier review Andrew Lunn suggested that we may be able to take a
different approach to this problem by using delays provided by the
KSZ9031RNX PHY. In particular MMD address 2h, Register 8h -
RGMII Clock Pad Skew.
I have consulted with Renesas regarding this suggestion, however,
unfortunately it appears that the delays provided by this solution
would be insufficient to allow for reliable 1Gbps communication.
At this point I believe the safest option is to apply this patch.
---
arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts | 1 +
arch/arm64/boot/dts/renesas/r8a77995-draak.dts | 1 +
2 files changed, 2 insertions(+)
diff --git a/arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts b/arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts
index 83fc13ac3fa1..3d3d6d438a05 100644
--- a/arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts
+++ b/arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts
@@ -271,6 +271,7 @@
interrupt-parent = <&gpio2>;
interrupts = <21 IRQ_TYPE_LEVEL_LOW>;
reset-gpios = <&gpio1 20 GPIO_ACTIVE_LOW>;
+ max-speed = <100>;
};
};
diff --git a/arch/arm64/boot/dts/renesas/r8a77995-draak.dts b/arch/arm64/boot/dts/renesas/r8a77995-draak.dts
index 0711170b26b1..eb153323ed13 100644
--- a/arch/arm64/boot/dts/renesas/r8a77995-draak.dts
+++ b/arch/arm64/boot/dts/renesas/r8a77995-draak.dts
@@ -175,6 +175,7 @@
reg = <0>;
interrupt-parent = <&gpio5>;
interrupts = <19 IRQ_TYPE_LEVEL_LOW>;
+ max-speed = <100>;
};
};
--
2.11.0
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next reply other threads:[~2019-07-17 12:57 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-17 12:57 Simon Horman [this message]
2019-07-17 13:24 ` [PATCH/RFC repost] arm64: dts: renesas: ebisu, draak: Limit EtherAVB to 100Mbps Kieran Bingham
2019-07-24 10:52 ` Simon Horman
2019-07-17 13:26 ` Wolfram Sang
2019-07-24 10:52 ` Simon Horman
2019-07-24 21:04 ` Wolfram Sang
2019-07-25 5:57 ` Simon Horman
2019-07-25 7:35 ` Wolfram Sang
2019-07-25 9:51 ` Simon Horman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190717125739.21450-1-horms+renesas@verge.net.au \
--to=horms+renesas@verge.net.au \
--cc=andrew@lunn.ch \
--cc=geert+renesas@glider.be \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-renesas-soc@vger.kernel.org \
--cc=magnus.damm@gmail.com \
--cc=wsa@the-dreams.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).