linux-kernel - RE: [PATCH 01/11] i2c: imx-lpi2c: directly retrun ISR when detect a NACK

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Message-ID: <AM6PR04MB49664AED0BD2246B79C7120980689@AM6PR04MB4966.eurprd04.prod.outlook.com>
Date:   Fri, 19 Mar 2021 04:25:44 +0000
From:   Aisheng Dong <aisheng.dong@....com>
To:     Clark Wang <xiaoning.wang@....com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>
CC:     "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        dl-linux-imx <linux-imx@....com>,
        "sumit.semwal@...aro.org" <sumit.semwal@...aro.org>,
        "christian.koenig@....com" <christian.koenig@....com>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 01/11] i2c: imx-lpi2c: directly retrun ISR when detect a
 NACK

> From: Clark Wang <xiaoning.wang@....com>
> Sent: Wednesday, March 17, 2021 2:54 PM
> 
> A NACK flag in ISR means i2c bus error. In such codition, there is no need to do
> read/write operation. It's better to return ISR directly and then stop i2c
> transfer.
> 
> Signed-off-by: Gao Pan <pandy.gao@....com>
> Signed-off-by: Clark Wang <xiaoning.wang@....com>

Reviewed-by: Dong Aisheng <aisheng.dong@....com>

Regards
Aisheng

> ---
>  drivers/i2c/busses/i2c-imx-lpi2c.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c
> b/drivers/i2c/busses/i2c-imx-lpi2c.c
> index 9db6ccded5e9..bbf44ac95021 100644
> --- a/drivers/i2c/busses/i2c-imx-lpi2c.c
> +++ b/drivers/i2c/busses/i2c-imx-lpi2c.c
> @@ -507,15 +507,17 @@ static irqreturn_t lpi2c_imx_isr(int irq, void *dev_id)
>  	lpi2c_imx_intctrl(lpi2c_imx, 0);
>  	temp = readl(lpi2c_imx->base + LPI2C_MSR);
> 
> +	if (temp & MSR_NDF) {
> +		complete(&lpi2c_imx->complete);
> +		goto ret;
> +	}
> +
>  	if (temp & MSR_RDF)
>  		lpi2c_imx_read_rxfifo(lpi2c_imx);
> -
> -	if (temp & MSR_TDF)
> +	else if (temp & MSR_TDF)
>  		lpi2c_imx_write_txfifo(lpi2c_imx);
> 
> -	if (temp & MSR_NDF)
> -		complete(&lpi2c_imx->complete);
> -
> +ret:
>  	return IRQ_HANDLED;
>  }
> 
> --
> 2.25.1