linux-kernel - Re: [PATCH v4 1/2] soundwire: qcom: Add flag for software clock gating check

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Date:   Thu, 9 Jun 2022 10:22:35 -0500
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Srinivasa Rao Mandadapu <quic_srivasam@...cinc.com>,
        agross@...nel.org, bjorn.andersson@...aro.org, lgirdwood@...il.com,
        broonie@...nel.org, robh+dt@...nel.org, quic_plai@...cinc.com,
        bgoswami@...cinc.com, perex@...ex.cz, tiwai@...e.com,
        srinivas.kandagatla@...aro.org, quic_rohkumar@...cinc.com,
        linux-arm-msm@...r.kernel.org, alsa-devel@...a-project.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        swboyd@...omium.org, judyhsiao@...omium.org, vkoul@...nel.org
Subject: Re: [PATCH v4 1/2] soundwire: qcom: Add flag for software clock
 gating check



On 6/9/22 09:30, Srinivasa Rao Mandadapu wrote:
> Validate software clock gating required or not and do software
> clock gating on hclk if soundwire is operational and keep it
> running by adding flag in private data structure.
> This is to avoid conflict between older architectures,
> where software clock gating is not required and on latest
> architectues, where software clock gating is mandatory.

architectures.

> 
> Signed-off-by: Srinivasa Rao Mandadapu <quic_srivasam@...cinc.com>
> Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> ---
>  drivers/soundwire/qcom.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/soundwire/qcom.c b/drivers/soundwire/qcom.c
> index a3fccf0..8e163da 100644
> --- a/drivers/soundwire/qcom.c
> +++ b/drivers/soundwire/qcom.c
> @@ -181,6 +181,7 @@ struct qcom_swrm_ctrl {
>  struct qcom_swrm_data {
>  	u32 default_cols;
>  	u32 default_rows;
> +	bool sw_clk_gate_required;
>  };
>  
>  static const struct qcom_swrm_data swrm_v1_3_data = {
> @@ -1311,6 +1312,15 @@ static int qcom_swrm_probe(struct platform_device *pdev)
>  			return PTR_ERR(ctrl->mmio);
>  	}
>  
> +	if (data->sw_clk_gate_required) {
> +		ctrl->audio_cgcr = devm_reset_control_get_exclusive(dev, "swr_audio_cgcr");
> +		if (IS_ERR(ctrl->audio_cgcr)) {

You need to handle the NULL case, devm_reset_control_get_exclusive() can
return ERR_OR_NULL

https://elixir.bootlin.com/linux/latest/source/drivers/reset/core.c#L1045

> +			dev_err(dev, "Failed to get cgcr reset ctrl required for SW gating\n");
> +			ret = PTR_ERR(ctrl->audio_cgcr);
> +			goto err_init;
> +		}
> +	}
> +
>  	ctrl->irq = of_irq_get(dev->of_node, 0);
>  	if (ctrl->irq < 0) {
>  		ret = ctrl->irq;
> @@ -1336,10 +1346,6 @@ static int qcom_swrm_probe(struct platform_device *pdev)
>  	ctrl->bus.compute_params = &qcom_swrm_compute_params;
>  	ctrl->bus.clk_stop_timeout = 300;
>  
> -	ctrl->audio_cgcr = devm_reset_control_get_exclusive(dev, "swr_audio_cgcr");
> -	if (IS_ERR(ctrl->audio_cgcr))
> -		dev_err(dev, "Failed to get audio_cgcr reset required for soundwire-v1.6.0\n");
> -
>  	ret = qcom_swrm_get_port_config(ctrl);
>  	if (ret)
>  		goto err_clk;