Re: [PATCH] drivers: i2c: Fix qup fifo handling

From: "Pramod Gurav" <gpramod@codeaurora.org>
Cc: gpramod@codeaurora.org, architt@codeaurora.org,
	linux-arm-msm@vger.kernel.org, ntelkar@codeaurora.org,
	linux-kernel@vger.kernel.org, andy.gross@linaro.org,
	linux-i2c@vger.kernel.org, agross@codeaurora.org,
	linux-arm-kernel@lists.infradead.org, wsa@the-dreams.de,
	sricharan@codeaurora.org
Subject: Re: [PATCH] drivers: i2c: Fix qup fifo handling
Date: Tue, 1 Mar 2016 11:21:26 +0530	[thread overview]
Message-ID: <88126e39f7b4d4e13df5b12b28f580c6.squirrel@us.codeaurora.org> (raw)
In-Reply-To: <1456502334-8687-1-git-send-email-sricharan@codeaurora.org>


On Fri, February 26, 2016 9:28 pm, Sricharan R wrote:
> After the addition of V2 support, there was a regression observed
> when testing it on MSM8996. The reason is driver puts the controller
> in to RUN state and writes the data to be 'tx' ed in fifo. But controller
> has to be put in to 'PAUSE' state and data has to written to fifo. Then
> should be put in to 'RUN' state separately.
>
> Signed-off-by: Sricharan R <sricharan@codeaurora.org>

Tested-by: Pramod Gurav <gpramod@codeaurora.org>

Regards,
Pramod
> ---
>  drivers/i2c/busses/i2c-qup.c | 46
> +++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 39 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c
> index 30f3a2b..23eaabb 100644
> --- a/drivers/i2c/busses/i2c-qup.c
> +++ b/drivers/i2c/busses/i2c-qup.c
> @@ -372,6 +372,38 @@ static void qup_i2c_set_write_mode(struct qup_i2c_dev
> *qup, struct i2c_msg *msg)
>  	}
>  }
>
> +static int check_for_fifo_space(struct qup_i2c_dev *qup)
> +{
> +	int ret;
> +
> +	ret = qup_i2c_change_state(qup, QUP_PAUSE_STATE);
> +	if (ret)
> +		goto out;
> +
> +	ret = qup_i2c_wait_ready(qup, QUP_OUT_FULL,
> +				 RESET_BIT, 4 * ONE_BYTE);
> +	if (ret) {
> +		/* Fifo is full. Drain out the fifo */
> +		ret = qup_i2c_change_state(qup, QUP_RUN_STATE);
> +		if (ret)
> +			goto out;
> +
> +		ret = qup_i2c_wait_ready(qup, QUP_OUT_NOT_EMPTY,
> +					 RESET_BIT, 256 * ONE_BYTE);
> +		if (ret) {
> +			dev_err(qup->dev, "timeout for fifo out full");
> +			goto out;
> +		}
> +
> +		ret = qup_i2c_change_state(qup, QUP_PAUSE_STATE);
> +		if (ret)
> +			goto out;
> +	}
> +
> +out:
> +	return ret;
> +}
> +
>  static int qup_i2c_issue_write(struct qup_i2c_dev *qup, struct i2c_msg
> *msg)
>  {
>  	u32 addr = msg->addr << 1;
> @@ -390,8 +422,7 @@ static int qup_i2c_issue_write(struct qup_i2c_dev
> *qup, struct i2c_msg *msg)
>
>  	while (qup->pos < msg->len) {
>  		/* Check that there's space in the FIFO for our pair */
> -		ret = qup_i2c_wait_ready(qup, QUP_OUT_FULL, RESET_BIT,
> -					 4 * ONE_BYTE);
> +		ret = check_for_fifo_space(qup);
>  		if (ret)
>  			return ret;
>
> @@ -413,6 +444,8 @@ static int qup_i2c_issue_write(struct qup_i2c_dev
> *qup, struct i2c_msg *msg)
>  		idx++;
>  	}
>
> +	ret = qup_i2c_change_state(qup, QUP_RUN_STATE);
> +
>  	return ret;
>  }
>
> @@ -441,12 +474,9 @@ static int qup_i2c_send_data(struct qup_i2c_dev *qup,
> int tlen, u8 *tbuf,
>  	int ret = 0;
>
>  	while (len > 0) {
> -		ret = qup_i2c_wait_ready(qup, QUP_OUT_FULL,
> -					 RESET_BIT, 4 * ONE_BYTE);
> -		if (ret) {
> -			dev_err(qup->dev, "timeout for fifo out full");
> +		ret = check_for_fifo_space(qup);
> +		if (ret)
>  			return ret;
> -		}
>
>  		t = (len >= 4) ? 4 : len;
>
> @@ -465,6 +495,8 @@ static int qup_i2c_send_data(struct qup_i2c_dev *qup,
> int tlen, u8 *tbuf,
>  		len -= 4;
>  	}
>
> +	ret = qup_i2c_change_state(qup, QUP_RUN_STATE);
> +
>  	return ret;
>  }
>
> --
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
> of Code Aurora Forum, hosted by The Linux Foundation
>
>
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>


Pramod
--
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