linux-kernel - Re: [PATCH v2] i2c: ocores: generate stop condition after timeout in polling mode

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Date:   Thu, 13 Apr 2023 16:05:54 +0200
From:   Federico Vaga <federico.vaga@...n.ch>
To:     Matthias Schiffer <matthias.schiffer@...tq-group.com>
Cc:     Peter Korsgaard <peter@...sgaard.com>,
        Andrew Lunn <andrew@...n.ch>, Wolfram Sang <wsa@...nel.org>,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux@...tq-group.com,
        Gregor Herburger <gregor.herburger@...group.com>
Subject: Re: [PATCH v2] i2c: ocores: generate stop condition after timeout in
 polling mode

On Thu, Apr 13, 2023 at 11:37:37AM +0200, Matthias Schiffer wrote:
>From: Gregor Herburger <gregor.herburger@...group.com>
>
>In polling mode, no stop condition is generated after a timeout. This
>causes SCL to remain low and thereby block the bus. If this happens
>during a transfer it can cause slaves to misinterpret the subsequent
>transfer and return wrong values.
>
>To solve this, pass the ETIMEDOUT error up from ocores_process_polling()
>instead of setting STATE_ERROR directly. The caller is adjusted to call
>ocores_process_timeout() on error both in polling and in IRQ mode, which
>will set STATE_ERROR and generate a stop condition.
>
>Fixes: 69c8c0c0efa8 ("i2c: ocores: add polling interface")
>Signed-off-by: Gregor Herburger <gregor.herburger@...group.com>
>Signed-off-by: Matthias Schiffer <matthias.schiffer@...tq-group.com>
>---
>
>v2: style improvements based on feedback from Federico and Andrew. I went
>    with a slightly different solution than Andrew suggested to avoid using
>    the ret variable for two different kinds of returns.
>
> drivers/i2c/busses/i2c-ocores.c | 35 ++++++++++++++++++---------------
> 1 file changed, 19 insertions(+), 16 deletions(-)

Reviewed-by: Federico Vaga <federico.vaga@...n.ch>

-- 
Federico Vaga - CERN BE-CEM-EDL