linux-kernel - Re: [V2,2/2] drivers: i2c: qup: Fix error handling

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Message-ID: <b2353f0e-3516-6bce-688a-2eeee2244ec8@codeaurora.org>
Date:	Fri, 6 May 2016 11:53:07 -0600
From:	Naveen Kaje <nkaje@...eaurora.org>
To:	Sricharan R <sricharan@...eaurora.org>, devicetree@...r.kernel.org,
	architt@...eaurora.org, linux-arm-msm@...r.kernel.org,
	ntelkar@...eaurora.org, galak@...eaurora.org,
	linux-kernel@...r.kernel.org, andy.gross@...aro.org,
	linux-i2c@...r.kernel.org, iivanov@...sol.com,
	agross@...eaurora.org, dmaengine@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [V2,2/2] drivers: i2c: qup: Fix error handling


On 5/6/2016 5:31 AM, Sricharan R wrote:
> Among the bus errors reported from the QUP_MASTER_STATUS register
> only NACK is considered and transfer gets suspended, while
> other errors are ignored. Correct this and suspend the transfer
> for other errors as well. This avoids unnessecary 'timeouts' which
> happens when waiting for events that would never happen when there
> is already an error condition on the bus.
>
> Signed-off-by: Sricharan R <sricharan@...eaurora.org>
> Reviewed-by: Andy Gross <andy.gross@...aro.org>
Hi Sricharan,
Looks good to me. Tested on QDF2432 platform.

Reviewed-by: Naveen Kaje <nkaje@...eaurora.org>
Tested-by: Naveen Kaje <nkaje@...eaurora.org>

> ---
>   drivers/i2c/busses/i2c-qup.c | 42 +++++++++++++++++++++++++++++-------------
>   1 file changed, 29 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c
> index 8620e99..af52a47 100644
> --- a/drivers/i2c/busses/i2c-qup.c
> +++ b/drivers/i2c/busses/i2c-qup.c
> @@ -310,6 +310,7 @@ static int qup_i2c_wait_ready(struct qup_i2c_dev *qup, int op, bool val,
>   	u32 opflags;
>   	u32 status;
>   	u32 shift = __ffs(op);
> +	int ret = 0;
>   
>   	len *= qup->one_byte_t;
>   	/* timeout after a wait of twice the max time */
> @@ -321,18 +322,31 @@ static int qup_i2c_wait_ready(struct qup_i2c_dev *qup, int op, bool val,
>   
>   		if (((opflags & op) >> shift) == val) {
>   			if ((op == QUP_OUT_NOT_EMPTY) && qup->is_last) {
> -				if (!(status & I2C_STATUS_BUS_ACTIVE))
> -					return 0;
> +				if (!(status & I2C_STATUS_BUS_ACTIVE)) {
> +					ret = 0;
> +					goto done;
> +				}
>   			} else {
> -				return 0;
> +				ret = 0;
> +				goto done;
>   			}
>   		}
>   
> -		if (time_after(jiffies, timeout))
> -			return -ETIMEDOUT;
> -
> +		if (time_after(jiffies, timeout)) {
> +			ret = -ETIMEDOUT;
> +			goto done;
> +		}
>   		usleep_range(len, len * 2);
>   	}
> +
> +done:
> +	if (qup->bus_err || qup->qup_err) {
> +		if (qup->bus_err & QUP_I2C_NACK_FLAG)
> +			dev_err(qup->dev, "NACK from %x\n", qup->msg->addr);
> +		ret = -EIO;
> +	}
> +
> +	return ret;
>   }
>   
>   static void qup_i2c_set_write_mode_v2(struct qup_i2c_dev *qup,
> @@ -796,7 +810,6 @@ static int qup_i2c_bam_do_xfer(struct qup_i2c_dev *qup, struct i2c_msg *msg,
>   		if (qup->bus_err & QUP_I2C_NACK_FLAG) {
>   			msg--;
>   			dev_err(qup->dev, "NACK from %x\n", msg->addr);
> -			ret = -EIO;
>   
>   			if (qup_i2c_change_state(qup, QUP_RUN_STATE)) {
>   				dev_err(qup->dev, "change to run state timed out");
> @@ -818,6 +831,7 @@ static int qup_i2c_bam_do_xfer(struct qup_i2c_dev *qup, struct i2c_msg *msg,
>   
>   			qup_i2c_rel_dma(qup);
>   		}
> +		ret = -EIO;
>   	}
>   
>   	dma_unmap_sg(qup->dev, qup->btx.sg, tx_nents, DMA_TO_DEVICE);
> @@ -841,9 +855,6 @@ static int qup_i2c_bam_xfer(struct i2c_adapter *adap, struct i2c_msg *msg,
>   	if (ret)
>   		goto out;
>   
> -	qup->bus_err = 0;
> -	qup->qup_err = 0;
> -
>   	writel(0, qup->base + QUP_MX_INPUT_CNT);
>   	writel(0, qup->base + QUP_MX_OUTPUT_CNT);
>   
> @@ -882,10 +893,9 @@ static int qup_i2c_wait_for_complete(struct qup_i2c_dev *qup,
>   	}
>   
>   	if (qup->bus_err || qup->qup_err) {
> -		if (qup->bus_err & QUP_I2C_NACK_FLAG) {
> +		if (qup->bus_err & QUP_I2C_NACK_FLAG)
>   			dev_err(qup->dev, "NACK from %x\n", msg->addr);
> -			ret = -EIO;
> -		}
> +		ret = -EIO;
>   	}
>   
>   	return ret;
> @@ -1178,6 +1188,9 @@ static int qup_i2c_xfer(struct i2c_adapter *adap,
>   	if (ret < 0)
>   		goto out;
>   
> +	qup->bus_err = 0;
> +	qup->qup_err = 0;
> +
>   	writel(1, qup->base + QUP_SW_RESET);
>   	ret = qup_i2c_poll_state(qup, QUP_RESET_STATE);
>   	if (ret)
> @@ -1227,6 +1240,9 @@ static int qup_i2c_xfer_v2(struct i2c_adapter *adap,
>   	struct qup_i2c_dev *qup = i2c_get_adapdata(adap);
>   	int ret, len, idx = 0, use_dma = 0;
>   
> +	qup->bus_err = 0;
> +	qup->qup_err = 0;
> +
>   	ret = pm_runtime_get_sync(qup->dev);
>   	if (ret < 0)
>   		goto out;