linux-kernel - Re: [PATCH v2] soundwire: qcom: remove redundant wait for completion

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Message-ID: <764e7a03-048b-750e-49ef-106863775738@quicinc.com>
Date:   Sat, 26 Feb 2022 18:17:58 +0530
From:   Srinivasa Rao Mandadapu <quic_srivasam@...cinc.com>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        "Srinivas Kandagatla" <srinivas.kandagatla@...aro.org>,
        <agross@...nel.org>, <bjorn.andersson@...aro.org>,
        <lgirdwood@...il.com>, <broonie@...nel.org>, <robh+dt@...nel.org>,
        <quic_plai@...cinc.com>, <bgoswami@...eaurora.org>,
        <perex@...ex.cz>, <tiwai@...e.com>, <rohitkr@...eaurora.org>,
        <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>,
        <yung-chuan.liao@...ux.intel.com>, <sanyog.r.kale@...el.com>
CC:     Venkata Prasad Potturu <quic_potturu@...cinc.com>
Subject: Re: [PATCH v2] soundwire: qcom: remove redundant wait for completion


On 2/25/2022 9:13 PM, Pierre-Louis Bossart wrote:
Thanks for your time Bossart!!!
>
> On 2/25/22 08:45, Srinivas Kandagatla wrote:
>>
>> On 25/02/2022 14:44, Srinivasa Rao Mandadapu wrote:
>>> Remove wait_for_completion_timeout from soundwire probe as it seems
>>> unnecessary and device enumeration is anyway not happening here,
>>> hence this api is blocking till it completes max wait time.
>>> Also, as device enumeration event is dependent on wcd938x probe to be
>>> completed, its of no use waiting here.
>>> Waiting here increasing the boot time almost 4 seconds and impacting
>>> other modules like touch screen.
>>>
>>> Fixes: 06dd96738d618 ("soundwire: qcom: wait for enumeration to be
>>> complete in probe")
>>>
>>> Signed-off-by: Srinivasa Rao Mandadapu <quic_srivasam@...cinc.com>
>>> Co-developed-by: Venkata Prasad Potturu <quic_potturu@...cinc.com>
>>> Signed-off-by: Venkata Prasad Potturu <quic_potturu@...cinc.com>
>> LGTM,
>>
>> Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> I don't get the idea, sorry.
>
> If you look at the code, these are the cases where this 'struct
> completion' is used
>
> 	struct completion enumeration;
> 	complete(&ctrl->enumeration);
> 	/* Enable Auto enumeration */
> 	init_completion(&ctrl->enumeration);
> 	wait_for_completion_timeout(&ctrl->enumeration,
>
>
> so if you remove the wait_for_completeion, then you might just as well
> remove the whole thing and revert 06dd96738d618
>
> what am I missing?
Okay. Sent new patch with reverting commit 06dd96738d618
>
>
>>> ---
>>>    drivers/soundwire/qcom.c | 2 --
>>>    1 file changed, 2 deletions(-)
>>>
>>> diff --git a/drivers/soundwire/qcom.c b/drivers/soundwire/qcom.c
>>> index 5481341..9a32a24 100644
>>> --- a/drivers/soundwire/qcom.c
>>> +++ b/drivers/soundwire/qcom.c
>>> @@ -1309,8 +1309,6 @@ static int qcom_swrm_probe(struct
>>> platform_device *pdev)
>>>        }
>>>          qcom_swrm_init(ctrl);
>>> -    wait_for_completion_timeout(&ctrl->enumeration,
>>> -                    msecs_to_jiffies(TIMEOUT_MS));
>>>        ret = qcom_swrm_register_dais(ctrl);
>>>        if (ret)
>>>            goto err_master_add;