linux-kernel - Re: [PATCH v3] i2c: bcm-iproc: Add i2c recovery support

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Message-ID: <YaUjd747t94Ge/VA@kunai>
Date:   Mon, 29 Nov 2021 20:01:11 +0100
From:   Wolfram Sang <wsa@...nel.org>
To:     Chris Packham <chris.packham@...iedtelesis.co.nz>
Cc:     rjui@...adcom.com, sbranden@...adcom.com,
        bcm-kernel-feedback-list@...adcom.com, linux-i2c@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Richard Laing <richard.laing@...iedtelesis.co.nz>
Subject: Re: [PATCH v3] i2c: bcm-iproc: Add i2c recovery support

Hi Chris,

sorry for the long delay.

All looks good except for this:

> @@ -806,6 +954,7 @@ static int bcm_iproc_i2c_xfer_wait(struct bcm_iproc_i2c_dev *iproc_i2c,
>  		/* flush both TX/RX FIFOs */
>  		val = BIT(M_FIFO_RX_FLUSH_SHIFT) | BIT(M_FIFO_TX_FLUSH_SHIFT);
>  		iproc_i2c_wr_reg(iproc_i2c, M_FIFO_CTRL_OFFSET, val);
> +		iproc_i2c_lockup_recover(iproc_i2c);
>  		return -ETIMEDOUT;
>  	}
>  
> @@ -814,6 +963,7 @@ static int bcm_iproc_i2c_xfer_wait(struct bcm_iproc_i2c_dev *iproc_i2c,
>  		/* flush both TX/RX FIFOs */
>  		val = BIT(M_FIFO_RX_FLUSH_SHIFT) | BIT(M_FIFO_TX_FLUSH_SHIFT);
>  		iproc_i2c_wr_reg(iproc_i2c, M_FIFO_CTRL_OFFSET, val);
> +		iproc_i2c_lockup_recover(iproc_i2c);
>  		return ret;
>  	}

I2C specs suggest recovery at the beginning of a transfer when SDA is
detected low. Not at the end of a transfer.

Happy hacking,

   Wolfram


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