linux-kernel - Re: [PATCH v2] ASoC: qcom: soundwire: Add support for controlling audio CGCR from HLOS

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Message-ID: <1ec64a99-cfcf-c903-935b-d1bb0617c284@linaro.org>
Date:   Wed, 1 Jun 2022 14:06:43 +0100
From:   Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:     Srinivasa Rao Mandadapu <quic_srivasam@...cinc.com>,
        Matthias Kaehlcke <mka@...omium.org>
Cc:     Stephen Boyd <swboyd@...omium.org>, agross@...nel.org,
        alsa-devel@...a-project.org, bgoswami@...cinc.com,
        bjorn.andersson@...aro.org, broonie@...nel.org,
        devicetree@...r.kernel.org, judyhsiao@...omium.org,
        lgirdwood@...il.com, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, perex@...ex.cz,
        quic_plai@...cinc.com, quic_rohkumar@...cinc.com,
        robh+dt@...nel.org, tiwai@...e.com, vkoul@...nel.org
Subject: Re: [PATCH v2] ASoC: qcom: soundwire: Add support for controlling
 audio CGCR from HLOS



On 01/06/2022 13:57, Srinivasa Rao Mandadapu wrote:
> 
> On 6/1/2022 4:02 AM, Matthias Kaehlcke wrote:
> Thanks for Your Time Matthias!!!
>> On Tue, May 24, 2022 at 04:19:47PM +0530, Srinivasa Rao Mandadapu wrote:
>>> On 5/21/2022 8:43 AM, Stephen Boyd wrote:
>>> Thanks for your time Stephen!!!
>>>> Quoting Srinivasa Rao Mandadapu (2022-05-18 05:42:35)
>>>>> diff --git a/drivers/soundwire/qcom.c b/drivers/soundwire/qcom.c
>>>>> index da1ad7e..445e481 100644
>>>>> --- a/drivers/soundwire/qcom.c
>>>>> +++ b/drivers/soundwire/qcom.c
>>>>> @@ -1333,6 +1337,10 @@ 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");
>>>> Why is there no return on error here? Is the reset optional?
>>> Yes it's optional. For older platforms this is not required.
>> If it's optional then either there should be no error message, or the
>> error message should only be logged when the version is >= 1.6.0. There
>> are few things worse than a kernel log riddled with misleading error
>> messages.
> 
> In that case, it can be done like below. Kindly let me know your opinion 
> on this.
> 
> if (ctrl->version >= 0x01060000) {

This is not true 1.7+ variants do not require anything as such.

Why not add a flag in struct qcom_swrm_data and pass it as part of 
of_match data specific to this version?

--srini
>      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 = PTR_ERR(ctrl->audio_cgcr);
>              goto err_clk;
>          }
>      }
>