linux-kernel - Re: [PATCH 3/4] i2c: stm32f7: stop dma transfer in case of NACK

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Date:   Thu, 23 Sep 2021 10:37:45 +0200
From:   Pierre Yves MORDRET <pierre-yves.mordret@...s.st.com>
To:     Alain Volmat <alain.volmat@...s.st.com>, <wsa@...nel.org>
CC:     <alexandre.torgue@...s.st.com>, <linux-i2c@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <fabrice.gasnier@...s.st.com>,
        <amelie.delaunay@...s.st.com>
Subject: Re: [PATCH 3/4] i2c: stm32f7: stop dma transfer in case of NACK

Hi Alain

Look good to me

Reviewed-by: Pierre-Yves MORDRET <pierre-yves.mordret@...s.st.com>

Regards

On 9/20/21 5:21 PM, Alain Volmat wrote:
> In case of receiving a NACK, the dma transfer should be stopped
> to avoid feeding data into the FIFO.
> Also ensure to properly return the proper error code and avoid
> waiting for the end of the dma completion in case of
> error happening during the transmission.
> 
> Fixes: 7ecc8cfde553 ("i2c: i2c-stm32f7: Add DMA support")
> 
> Signed-off-by: Alain Volmat <alain.volmat@...s.st.com>
> ---
>  drivers/i2c/busses/i2c-stm32f7.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
> index ad3459a3bc5e..50d5ae81d227 100644
> --- a/drivers/i2c/busses/i2c-stm32f7.c
> +++ b/drivers/i2c/busses/i2c-stm32f7.c
> @@ -1493,6 +1493,7 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
>  {
>  	struct stm32f7_i2c_dev *i2c_dev = data;
>  	struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
> +	struct stm32_i2c_dma *dma = i2c_dev->dma;
>  	void __iomem *base = i2c_dev->base;
>  	u32 status, mask;
>  	int ret = IRQ_HANDLED;
> @@ -1518,6 +1519,10 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
>  		dev_dbg(i2c_dev->dev, "<%s>: Receive NACK (addr %x)\n",
>  			__func__, f7_msg->addr);
>  		writel_relaxed(STM32F7_I2C_ICR_NACKCF, base + STM32F7_I2C_ICR);
> +		if (i2c_dev->use_dma) {
> +			stm32f7_i2c_disable_dma_req(i2c_dev);
> +			dmaengine_terminate_all(dma->chan_using);
> +		}
>  		f7_msg->result = -ENXIO;
>  	}
>  
> @@ -1533,7 +1538,7 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
>  		/* Clear STOP flag */
>  		writel_relaxed(STM32F7_I2C_ICR_STOPCF, base + STM32F7_I2C_ICR);
>  
> -		if (i2c_dev->use_dma) {
> +		if (i2c_dev->use_dma && !f7_msg->result) {
>  			ret = IRQ_WAKE_THREAD;
>  		} else {
>  			i2c_dev->master_mode = false;
> @@ -1546,7 +1551,7 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
>  		if (f7_msg->stop) {
>  			mask = STM32F7_I2C_CR2_STOP;
>  			stm32f7_i2c_set_bits(base + STM32F7_I2C_CR2, mask);
> -		} else if (i2c_dev->use_dma) {
> +		} else if (i2c_dev->use_dma && !f7_msg->result) {
>  			ret = IRQ_WAKE_THREAD;
>  		} else if (f7_msg->smbus) {
>  			stm32f7_i2c_smbus_rep_start(i2c_dev);
> 

-- 
--
~ Py MORDRET
--