linux-kernel - Re: [PATCH v2 1/5] dmaengine: qcom: bam

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Message-ID: <20180214154144.GB93895@bjorns-mbp-2.lan>
Date:   Wed, 14 Feb 2018 07:41:44 -0800
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     srinivas.kandagatla@...aro.org
Cc:     vinod.koul@...el.com, andy.gross@...aro.org,
        dmaengine@...r.kernel.org, robh+dt@...nel.org,
        mark.rutland@....com, david.brown@...aro.org,
        dan.j.williams@...el.com, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-soc@...r.kernel.org, yanhe@...cinc.com,
        ramkri@....qualcomm.com, sdharia@...cinc.com
Subject: Re: [PATCH v2 1/5] dmaengine: qcom: bam_dma: make bam clk optional

On Wed 14 Feb 06:44 PST 2018, Srinivas Kandagatla wrote:
> @@ -1233,13 +1233,14 @@ static int bam_dma_probe(struct platform_device *pdev)
>  						"qcom,controlled-remotely");
>  
>  	bdev->bamclk = devm_clk_get(bdev->dev, "bam_clk");
> -	if (IS_ERR(bdev->bamclk))
> -		return PTR_ERR(bdev->bamclk);
> -
> -	ret = clk_prepare_enable(bdev->bamclk);
> -	if (ret) {
> -		dev_err(bdev->dev, "failed to prepare/enable clock\n");
> -		return ret;
> +	if (IS_ERR(bdev->bamclk)) {

In the case of !bdev->controlled_remotely I think this should still be
an error.

> +		bdev->bamclk = NULL;
> +	} else {
> +		ret = clk_prepare_enable(bdev->bamclk);
> +		if (ret) {
> +			dev_err(bdev->dev, "failed to prepare/enable clock\n");
> +			return ret;
> +		}

The rest of the driver will keep operating the bamclk (which is okay),
so for symmetry purposes I think you should just keep the
clk_prepare_enable() block unmodified.

Regards,
Bjorn