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

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Date:   Thu, 10 Oct 2019 08:54:09 +0200
From:   Ludovic Desroches <ludovic.desroches@...rochip.com>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>
CC:     Kamel Bouhara <kamel.bouhara@...tlin.com>,
        Wolfram Sang <wsa@...-dreams.de>, <linux-i2c@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Nicolas Ferre <nicolas.ferre@...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 09, 2019 at 04:01:47PM +0200, Alexandre Belloni wrote:
> 
> On 09/10/2019 15:55:00+0200, Ludovic Desroches wrote:
> > On Wed, Oct 02, 2019 at 04:46:56PM +0200, Kamel Bouhara wrote:
> > > External E-Mail
> > > 
> > > 
> > > 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.
> > > 
> > 
> > Hi Kamel,
> > 
> > Thanks for adding this new feature. As I see patches only for sama5d3 and
> > sama5d4, I assume it has not been tested with a sama5d2, isn't it?
> > 
> 
> I there a point having it on sama5d2 as the controller already supports
> this feature?
> 

Right, I was focused on pinctrl and forget we have this feature
supported by the IP.

> > I doubt it works with a sama5d2 because of the pinctrl. I also wonder if it can
> > work if we add .strict = true to pinmux_ops which is something plan for the
> > future...
> > 
> 
> I don't see why it wouldn't work with strict as this is switching muxing
> properly instead of using the pins for two functions at the same time.
> 

Not sure devm_gpiod_get won't fail with strict.

Ludovic