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From: Wolfram Sang <wsa@the-dreams.de>
To: Simon Horman <horms+renesas@verge.net.au>
Cc: linux-renesas-soc@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Magnus Damm <magnus.damm@gmail.com>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
	Wolfram Sang <wsa+renesas@sang-engineering.com>,
	Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Subject: Re: [PATCH/RFC] arm64: dts: renesas: ebisu, draak: Limit EtherAVB to 100Mbps
Date: Mon, 8 Apr 2019 10:41:43 +0200	[thread overview]
Message-ID: <20190408084143.GA1615@kunai> (raw)
In-Reply-To: <20190408083148.23134-1-horms+renesas@verge.net.au>

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Hi Simon,

On Mon, Apr 08, 2019 at 10:31:48AM +0200, Simon Horman wrote:
> * 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.

"cannot" missing?

> Based on work by Kazuya Mizuguchi.
> 
> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
> ---
>  arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts | 1 +
>  arch/arm64/boot/dts/renesas/r8a77995-draak.dts | 1 +
>  2 files changed, 2 insertions(+)
> 
>  Based on renesas-devel-20190404-v5.1-rc3
> 
> diff --git a/arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts b/arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts
> index c72772589953..05214b8dd2c5 100644
> --- a/arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts
> +++ b/arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts
> @@ -272,6 +272,7 @@
>  		interrupt-parent = <&gpio2>;
>  		interrupts = <21 IRQ_TYPE_LEVEL_LOW>;
>  		reset-gpios = <&gpio1 20 GPIO_ACTIVE_LOW>;
> +		max-speed = <100>;

What about adding a comment explaining this speed limit?

Thanks,

   Wolfram


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WARNING: multiple messages have this Message-ID (diff)
From: Wolfram Sang <wsa@the-dreams.de>
To: Simon Horman <horms+renesas@verge.net.au>
Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
	Magnus Damm <magnus.damm@gmail.com>,
	linux-renesas-soc@vger.kernel.org,
	Wolfram Sang <wsa+renesas@sang-engineering.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH/RFC] arm64: dts: renesas: ebisu, draak: Limit EtherAVB to 100Mbps
Date: Mon, 8 Apr 2019 10:41:43 +0200	[thread overview]
Message-ID: <20190408084143.GA1615@kunai> (raw)
In-Reply-To: <20190408083148.23134-1-horms+renesas@verge.net.au>


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Hi Simon,

On Mon, Apr 08, 2019 at 10:31:48AM +0200, Simon Horman wrote:
> * 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.

"cannot" missing?

> Based on work by Kazuya Mizuguchi.
> 
> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
> ---
>  arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts | 1 +
>  arch/arm64/boot/dts/renesas/r8a77995-draak.dts | 1 +
>  2 files changed, 2 insertions(+)
> 
>  Based on renesas-devel-20190404-v5.1-rc3
> 
> diff --git a/arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts b/arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts
> index c72772589953..05214b8dd2c5 100644
> --- a/arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts
> +++ b/arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts
> @@ -272,6 +272,7 @@
>  		interrupt-parent = <&gpio2>;
>  		interrupts = <21 IRQ_TYPE_LEVEL_LOW>;
>  		reset-gpios = <&gpio1 20 GPIO_ACTIVE_LOW>;
> +		max-speed = <100>;

What about adding a comment explaining this speed limit?

Thanks,

   Wolfram


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  reply	other threads:[~2019-04-08  8:41 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-08  8:31 [PATCH/RFC] arm64: dts: renesas: ebisu, draak: Limit EtherAVB to 100Mbps Simon Horman
2019-04-08  8:31 ` Simon Horman
2019-04-08  8:41 ` Wolfram Sang [this message]
2019-04-08  8:41   ` Wolfram Sang
2019-04-08  9:45   ` Simon Horman
2019-04-08  9:45     ` Simon Horman
2019-04-08 10:56     ` Wolfram Sang
2019-04-08 10:56       ` Wolfram Sang
2019-04-08 21:26 ` Andrew Lunn
2019-04-08 21:26   ` Andrew Lunn
2019-04-10  9:27   ` Simon Horman
2019-04-10  9:27     ` Simon Horman

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