linux-kernel - Re: [PATCH 01/12] i2c: qup: fixed releasing dma without flush operation completion

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Date:   Tue, 27 Feb 2018 14:46:53 -0700
From:   "Christ, Austin" <austinwc@...eaurora.org>
To:     Abhishek Sahu <absahu@...eaurora.org>,
        Andy Gross <andy.gross@...aro.org>,
        Wolfram Sang <wsa@...-dreams.de>
Cc:     David Brown <david.brown@...aro.org>,
        Sricharan R <sricharan@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/12] i2c: qup: fixed releasing dma without flush
 operation completion

Tested on Centriq 2400

Reviewed-by: Austin Christ <austinwc@...eaurora.org>

On 2/3/2018 12:58 AM, Abhishek Sahu wrote:
> The QUP BSLP BAM generates the following error sometimes if the
> current I2C DMA transfer fails and the flush operation has been
> scheduled
> 
>      “bam-dma-engine 7884000.dma: Cannot free busy channel”
> 
> If any I2C error comes during BAM DMA transfer, then the QUP I2C
> interrupt will be generated and the flush operation will be
> carried out to make i2c consume all scheduled DMA transfer.
> Currently, the same completion structure is being used for BAM
> transfer which has already completed without reinit. It will make
> flush operation wait_for_completion_timeout completed immediately
> and will proceed for freeing the DMA resources where the
> descriptors are still in process.
> 
> Signed-off-by: Abhishek Sahu <absahu@...eaurora.org>
> ---
>   drivers/i2c/busses/i2c-qup.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c
> index 08f8e01..9faa26c41a 100644
> --- a/drivers/i2c/busses/i2c-qup.c
> +++ b/drivers/i2c/busses/i2c-qup.c
> @@ -1,5 +1,5 @@
>   /*
> - * Copyright (c) 2009-2013, The Linux Foundation. All rights reserved.
> + * Copyright (c) 2009-2013, 2016-2018, The Linux Foundation. All rights reserved.
>    * Copyright (c) 2014, Sony Mobile Communications AB.
>    *
>    *
> @@ -844,6 +844,8 @@ static int qup_i2c_bam_do_xfer(struct qup_i2c_dev *qup, struct i2c_msg *msg,
>   	}
>   
>   	if (ret || qup->bus_err || qup->qup_err) {
> +		reinit_completion(&qup->xfer);
> +
>   		if (qup_i2c_change_state(qup, QUP_RUN_STATE)) {
>   			dev_err(qup->dev, "change to run state timed out");
>   			goto desc_err;
> 

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