linux-kernel - Re: [PATCH V2 03/15] coresight: tmc: re-implementing tmc_read

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Date:	Thu, 14 Apr 2016 18:11:33 +0100
From:	Suzuki K Poulose <Suzuki.Poulose@....com>
To:	Mathieu Poirier <mathieu.poirier@...aro.org>,
	linux-arm-kernel@...ts.infradead.org
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 03/15] coresight: tmc: re-implementing
 tmc_read_prepare/unprepare() functions

On 12/04/16 18:54, Mathieu Poirier wrote:
> In their current implementation the tmc_read_prepare/unprepare()
> are a lump of if/else that is difficult to read.  This patch is
> alleviating that by using a switch statement.  The latter also
> allows for a better control on the error path.
>
> Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
> ---
>   drivers/hwtracing/coresight/coresight-tmc.c | 56 ++++++++++++++++++-----------
>   1 file changed, 36 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc.c b/drivers/hwtracing/coresight/coresight-tmc.c
> index 66fa7736d12f..d211aeec49f8 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc.c
> @@ -431,7 +431,7 @@ static const struct coresight_ops tmc_etf_cs_ops = {
>
>   static int tmc_read_prepare(struct tmc_drvdata *drvdata)
>   {
> -	int ret;
> +	int ret = 0;
>   	unsigned long flags;
>   	enum tmc_mode mode;
>
> @@ -439,25 +439,31 @@ static int tmc_read_prepare(struct tmc_drvdata *drvdata)
>   	if (!drvdata->enable)
>   		goto out;
>
> -	if (drvdata->config_type == TMC_CONFIG_TYPE_ETB) {
> +	switch (drvdata->config_type) {
> +	case TMC_CONFIG_TYPE_ETB:
>   		tmc_etb_disable_hw(drvdata);
> -	} else if (drvdata->config_type == TMC_CONFIG_TYPE_ETR) {
> -		tmc_etr_disable_hw(drvdata);
> -	} else {
> +		break;
> +	case TMC_CONFIG_TYPE_ETF:
> +		/* There is no point in reading a TMC in HW FIFO mode */
>   		mode = readl_relaxed(drvdata->base + TMC_MODE);
> -		if (mode == TMC_MODE_CIRCULAR_BUFFER) {
> -			tmc_etb_disable_hw(drvdata);
> -		} else {
> -			ret = -ENODEV;
> +		if (mode != TMC_MODE_CIRCULAR_BUFFER) {
> +			ret = -EINVAL;
>   			goto err;
>   		}

Nit. If you move the TMC_CONFIG_TYPE_ETB here, you could fall through from TYPE_ETF: i.e,
		/* Fall through to ETB mode */
	case TMC_CONFIG_TYPE_ETB:
> +
> +		tmc_etb_disable_hw(drvdata);
> +		break;



> +	case TMC_CONFIG_TYPE_ETR:
> +		tmc_etr_disable_hw(drvdata);
> +		break;
> +	default:
> +		ret = -EINVAL;
> +		goto err;
>   	}
> +


>   	return ret;
> @@ -472,20 +478,30 @@ static void tmc_read_unprepare(struct tmc_drvdata *drvdata)
>   	if (!drvdata->enable)
>   		goto out;
>
> -	if (drvdata->config_type == TMC_CONFIG_TYPE_ETB) {
> +	switch (drvdata->config_type) {
> +	case TMC_CONFIG_TYPE_ETB:
>   		tmc_etb_enable_hw(drvdata);
> -	} else if (drvdata->config_type == TMC_CONFIG_TYPE_ETR) {
> -		tmc_etr_enable_hw(drvdata);
> -	} else {
> +		break;
> +	case TMC_CONFIG_TYPE_ETF:
> +		/* Make sure we don't re-enable a TMC in HW FIFO mode */
>   		mode = readl_relaxed(drvdata->base + TMC_MODE);
> -		if (mode == TMC_MODE_CIRCULAR_BUFFER)
> -			tmc_etb_enable_hw(drvdata);
> +		if (mode != TMC_MODE_CIRCULAR_BUFFER)
> +			goto err;
> +
> +		tmc_etb_enable_hw(drvdata);
> +		break;

Same as above.

> +	case TMC_CONFIG_TYPE_ETR:
> +		tmc_etr_disable_hw(drvdata);
> +		break;
> +	default:
> +		goto err;
>   	}
> +

Otherwise,

Reviewed-by: Suzuki K Poulose <suzuki.poulose@....com>