linux-kernel - Re: [PATCH] i2c: xiic: print error code when xiic_start

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Message-ID: <h6mggdcri53rq65jzi5ov6n7oqdvaldtpofh6eina6gos2wyyw@crjmnmfpynw4>
Date: Wed, 8 May 2024 14:51:34 +0200
From: Andi Shyti <andi.shyti@...nel.org>
To: marc.ferland@...il.com
Cc: michal.simek@....com, linux-arm-kernel@...ts.infradead.org, 
	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Marc Ferland <marc.ferland@...atest.com>
Subject: Re: [PATCH] i2c: xiic: print error code when xiic_start_xfer fails

Hi Marc,

On Mon, May 06, 2024 at 11:45:20AM -0400, marc.ferland@...il.com wrote:
> From: Marc Ferland <marc.ferland@...atest.com>
> 
> xiic_start_xfer can fail for different reasons:
> 
> - EBUSY: bus is busy or i2c messages still in tx_msg or rx_msg
> - ETIMEDOUT: timed-out trying to clear the RX fifo

Wolfram has recently removed all the error printouts caused by
etimedout.

> - EINVAL: wrong clock settings
> 
> Printing the error code helps identifying the root cause.
> 
> Signed-off-by: Marc Ferland <marc.ferland@...atest.com>
> ---
>  drivers/i2c/busses/i2c-xiic.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/busses/i2c-xiic.c b/drivers/i2c/busses/i2c-xiic.c
> index 71391b590ada..73729f0180a1 100644
> --- a/drivers/i2c/busses/i2c-xiic.c
> +++ b/drivers/i2c/busses/i2c-xiic.c
> @@ -1165,7 +1165,7 @@ static int xiic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
>  
>  	err = xiic_start_xfer(i2c, msgs, num);
>  	if (err < 0) {
> -		dev_err(adap->dev.parent, "Error xiic_start_xfer\n");
> +		dev_err(adap->dev.parent, "Error xiic_start_xfer: %d\n", err);

I don't see the end user being interested in having the error
number printed in the dmesg. In fact, I doubt the end user is
interested in this message at all.

We could print the debug messages (or warnings) where the actual
failure occurs. For example, in the setclk case, a warning is
already being printed, and I don't see why we should also print
an error here.

Does that make sense?

Andi

>  		goto out;
>  	}
>  
> -- 
> 2.34.1
>