linux-kernel - RE: [PATCH v6 1/2] dt-bindings: i2c: aspeed: support for AST2600-i2cv2

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Message-ID: <TYZPR06MB52746773023B98DF000224BDF2B59@TYZPR06MB5274.apcprd06.prod.outlook.com>
Date:   Thu, 9 Mar 2023 09:15:10 +0000
From:   Ryan Chen <ryan_chen@...eedtech.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Wolfram Sang <wsa@...nel.org>
CC:     Joel Stanley <joel@....id.au>,
        Brendan Higgins <brendan.higgins@...ux.dev>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Andrew Jeffery <andrew@...id.au>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        "linux-aspeed@...ts.ozlabs.org" <linux-aspeed@...ts.ozlabs.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "openbmc@...ts.ozlabs.org" <openbmc@...ts.ozlabs.org>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>
Subject: RE: [PATCH v6 1/2] dt-bindings: i2c: aspeed: support for
 AST2600-i2cv2

Hello Krzysztof,

> -----Original Message-----
> From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> Sent: Thursday, March 9, 2023 4:52 PM
> To: Ryan Chen <ryan_chen@...eedtech.com>; Wolfram Sang
> <wsa@...nel.org>
> Cc: Joel Stanley <joel@....id.au>; Brendan Higgins
> <brendan.higgins@...ux.dev>; Krzysztof Kozlowski
> <krzysztof.kozlowski+dt@...aro.org>; Andrew Jeffery <andrew@...id.au>;
> devicetree@...r.kernel.org; Philipp Zabel <p.zabel@...gutronix.de>; Rob
> Herring <robh+dt@...nel.org>; Benjamin Herrenschmidt
> <benh@...nel.crashing.org>; linux-aspeed@...ts.ozlabs.org;
> linux-arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org;
> openbmc@...ts.ozlabs.org; linux-i2c@...r.kernel.org
> Subject: Re: [PATCH v6 1/2] dt-bindings: i2c: aspeed: support for AST2600-i2cv2
> 
> On 07/03/2023 11:09, Ryan Chen wrote:
> >>>> 2. Why we do not have it for all controllers with SMBus v3? Why
> >>>> this one is special?
> >>>
> >>> Not all bus is connected with smbus. Most are i2c device connected in
> board.
> >>> That will be specific statement for each bus.
> >>
> >> That's not the answer to my question. Why other controllers which can
> >> be connected to I2C or SMBus devices do not need this property?
> >
> > For example following is the board specific connection.
> >
> > Board A                                         Board B
> > -------------------------                       ------------------------
> > |i2c bus#1(master/slave)  <===fingerprint ===> i2c bus#x (master/slave)|
> > |i2c bus#2(master)-> tmp i2c device |          |
> |
> > |i2c bus#3(master)-> adc i2c device |          |
> |
> > -------------------------                       ------------------------
> >
> > Bus#1 is mctp transfer for each BoardA/B. (Not smbus connected)
> > Bus#2 is i2c device connected.
> > Bus#3 is i2c device connected.
> 
> You are repeating the same stuff for my question. Where do you see on this
> diagram here other I2C controller? How does it answer my question?
> You keep repeating same and same, so it won't work.
> 
Sorry, my mis-understand.  
I don't see many controllers support for timeout feature.
I do study with other controllers that is implement it by sw impelement.
https://github.com/torvalds/linux/blob/master/drivers/i2c/busses/i2c-mlxbf.c#L302-L307
https://github.com/torvalds/linux/blob/master/drivers/i2c/busses/i2c-img-scb.c#L52-L55
https://github.com/torvalds/linux/blob/master/drivers/i2c/busses/i2c-omap.c#L588-L596

So I asking for aspeed,timeout property, If it not acceptable, I will default enable timeout in driver.
Thanks your guidance.



Best regards,
Ryan Chen