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Message-ID: <7c38c139-9a5d-f098-3252-cbf5fe51e776@motor-comm.com>
Date: Mon, 16 Jan 2023 10:49:43 +0800
From: "Frank.Sae" <Frank.Sae@...or-comm.com>
To: Andrew Lunn <andrew@...n.ch>
Cc: Peter Geis <pgwipeout@...il.com>,
Heiner Kallweit <hkallweit1@...il.com>,
Russell King <linux@...linux.org.uk>,
"David S . Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
xiaogang.fan@...or-comm.com, fei.zhang@...or-comm.com,
hua.sun@...or-comm.com, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH net-next v1 1/3] dt-bindings: net: Add Motorcomm yt8xxx
ethernet phy Driver bindings
Hi Andrew,
On 2023/1/11 21:07, Andrew Lunn wrote:
>> RX delay = rx-delay-basic (0ns or 1.9ns) + x-delay-additional-ps
>> (N*150ps, N = 0 ~ 15)
>> If rx-delay-basic is removed and controlled by phy-mode.
>> when phy-mode is rgmii-id or rgmii-rxid, RX delay is 1.9ns + N*150ps.
>> But sometimes 1.9ns is still too big, we just need 0ns + N*150ps.
>>
>> For this case, can we do like following ?
>> rx-internal-delay-ps:
>> enum: [ 0, 150, 300, 450, 600, 750, 900, 1050, 1200, 1350, 1500,
>> 1650, 1800, 1900, 1950, 2050, 2100, 2200, 2250, 2350, 2500, 2650, 2800,
>> 2950, 3100, 3250, 3400, 3550, 3700, 3850, 4000, 4150 ]
>> default: 0
>> rx-internal-delay-ps is 0ns + N*150ps and 1.9ns + N*150ps.
>> And check whether need rx-delay-basic (1.9ns) by the val of
>> rx-internal-delay-ps?
>
> Nothing says delays are only positive. So you could have rgmii-id or
> rgmii-rxid and a rx-internal-delay-ps of -150, if you need less than
> 1.9ns.
>
> As i said, rx-internal-delay-ps is used to fine tune the delay.
The standard type of rx-internal-delay-ps is uint32-array, so it can't
be -150.
https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/property-units.yaml
"-ps$":
$ref: types.yaml#/definitions/uint32-array
description: picosecond
Can we used rx-internal-delay-ps with int32 type?
like this:
rx-internal-delay-ps:
$ref: /schemas/types.yaml#/definitions/int32
enum: [ -1900, -1750, -1600, -1450, -1300, -1150, -1000, -850, -700,
-550, -400, -250, -100, 0, 50, 150, 200, 300, 350, 450, 600, 750, 900,
1050, 1200, 1350, 1500, 1650, 1800, 1950, 2100, 2250 ]
default: 0
>
>> We can't reduce this down to tx-clk-inverted.
>> There are two mac and two yt8531 on their board. Each of yt8531 need
>> different config in DTS. They need adjust tx clk delay in
>> link_change_notify callback function according to current speed.
>>
>> They configured tx-clk-xxxx-inverted like this :
>>
>> speed GMAC0 GMAC1
>> 1000M 1 0 tx-clk-1000-inverted
>> 100M 1 1 tx-clk-100-inverted
>> 10M 0/1 0/1 tx-clk-10-inverted
>
> What MAC is this? It seems very oddly designed, getting close to
> broken. I've not seen any other MAC/PHY combination need anything like
> this.
>
>> Can we put tx-clk-adj-enabled, tx-clk-10-inverted, tx-clk-100-inverted
>> and tx-clk-1000-inverted in tx-clk-10-inverted like bit in byte?
>
> No, they are individual boolean properties, so should be kept as they
> are. But i really think somebody should be looking deep into the MAC
> design to understand why it is like this, and if the MAC can sort out
> this mess itself.
>
> Andrew
Tanks. We will remove tx-clk-xxxx-inverted and tx-clk-adj-enabled.
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