linux-kernel - Re: [PATCH 2/4] i2c: at91: implement i2c bus recovery

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Message-ID: <20191021202044.GB3607@kunai>
Date:   Mon, 21 Oct 2019 22:20:44 +0200
From:   Wolfram Sang <wsa@...-dreams.de>
To:     Kamel Bouhara <kamel.bouhara@...tlin.com>
Cc:     linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH 2/4] i2c: at91: implement i2c bus recovery

On Wed, Oct 02, 2019 at 04:46:56PM +0200, Kamel Bouhara wrote:
> Implement i2c bus recovery when slaves devices might hold SDA low.
> In this case re-assign SCL/SDA to gpios and issue 9 dummy clock pulses
> until the slave release SDA.
> 
> Signed-off-by: Kamel Bouhara <kamel.bouhara@...tlin.com>

Setting up the bus_recovery looks OK. However, I don't see any call to
i2c_recover_bus(), so the bus_recovery is never used. Did you test this
and see an effect?

Also, I think we should merge this patch "[PATCH v3] i2c: at91: Send bus
clear command if SCL or SDA is down" into this series. The crucial thing
for both is when to apply the recovery (at the beginning of a
transfer!). The rest is "just" that some HW needs a bus_recovery_info
for pinctrl/GPIO handling (from this patch), while other HW needs a
bus_recovery_info with a custom recover_bus callback.

Opinions?

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