linux-kernel - Re: [PATCH v2 3/6] i2c: pasemi: Improve timeout handling

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Message-ID: <Z_6TV-tPU2wRdfFf@blossom>
Date: Tue, 15 Apr 2025 13:11:51 -0400
From: Alyssa Rosenzweig <alyssa@...enzweig.io>
To: sven@...npeter.dev
Cc: Janne Grunau <j@...nau.net>, Madhavan Srinivasan <maddy@...ux.ibm.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Naveen N Rao <naveen@...nel.org>,
	Andi Shyti <andi.shyti@...nel.org>, Neal Gompa <neal@...pa.dev>,
	Hector Martin <marcan@...can.st>, linuxppc-dev@...ts.ozlabs.org,
	asahi@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/6] i2c: pasemi: Improve timeout handling

Reviewed-by: Alyssa Rosenzweig <alyssa@...enzweig.io>

Le Tue , Apr 15, 2025 at 03:36:57PM +0000, Sven Peter via B4 Relay a écrit :
> From: Sven Peter <sven@...npeter.dev>
> 
> Add proper timeout handling for the interrupt path.
> Previously, this was only correctly done for the polling path.
> Note that we drop reg_write(smbus, REG_SMSTA, status) here which
> will be done anyway whenever the next transaction starts via
> pasemi_smb_clear.
> 
> Signed-off-by: Sven Peter <sven@...npeter.dev>
> ---
>  drivers/i2c/busses/i2c-pasemi-core.c | 24 +++++++++++++++++-------
>  1 file changed, 17 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-pasemi-core.c b/drivers/i2c/busses/i2c-pasemi-core.c
> index df1b0087dcacb0a3b94196368137d5e20b0e6d7e..9b611dbdfef23e78a4ea75ac0311938d52b6ba96 100644
> --- a/drivers/i2c/busses/i2c-pasemi-core.c
> +++ b/drivers/i2c/busses/i2c-pasemi-core.c
> @@ -91,32 +91,42 @@ static void pasemi_smb_clear(struct pasemi_smbus *smbus)
>  static int pasemi_smb_waitready(struct pasemi_smbus *smbus)
>  {
>  	int timeout = 100;
> +	int ret;
>  	unsigned int status;
>  
>  	if (smbus->use_irq) {
>  		reinit_completion(&smbus->irq_completion);
>  		reg_write(smbus, REG_IMASK, SMSTA_XEN | SMSTA_MTN);
> -		wait_for_completion_timeout(&smbus->irq_completion, msecs_to_jiffies(100));
> +		ret = wait_for_completion_timeout(&smbus->irq_completion, msecs_to_jiffies(100));
>  		reg_write(smbus, REG_IMASK, 0);
>  		status = reg_read(smbus, REG_SMSTA);
> +
> +		if (ret < 0) {
> +			dev_err(smbus->dev,
> +				"Completion wait failed with %d, status 0x%08x\n",
> +				ret, status);
> +			return ret;
> +		} else if (ret == 0) {
> +			dev_warn(smbus->dev, "Timeout, status 0x%08x\n", status);
> +			return -ETIME;
> +		}
>  	} else {
>  		status = reg_read(smbus, REG_SMSTA);
>  		while (!(status & SMSTA_XEN) && timeout--) {
>  			msleep(1);
>  			status = reg_read(smbus, REG_SMSTA);
>  		}
> +
> +		if (timeout < 0) {
> +			dev_warn(smbus->dev, "Timeout, status 0x%08x\n", status);
> +			return -ETIME;
> +		}
>  	}
>  
>  	/* Got NACK? */
>  	if (status & SMSTA_MTN)
>  		return -ENXIO;
>  
> -	if (timeout < 0) {
> -		dev_warn(smbus->dev, "Timeout, status 0x%08x\n", status);
> -		reg_write(smbus, REG_SMSTA, status);
> -		return -ETIME;
> -	}
> -
>  	/* Clear XEN */
>  	reg_write(smbus, REG_SMSTA, SMSTA_XEN);
>  
> 
> -- 
> 2.34.1
> 
>