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Message-ID: <17b2041d-7c9b-4cb4-bf39-7d0f5d60c04b@quicinc.com>
Date: Wed, 28 Feb 2024 10:08:45 +0800
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Subject: Re: [PATCH v3 2/3] net: qrtr: support suspend/hibernation
Content-Language: en-US
To: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
CC: <ath11k@lists.infradead.org>, <linux-wireless@vger.kernel.org>,
        <linux-arm-msm@vger.kernel.org>, <mhi@lists.linux.dev>
References: <20240227104427.7505-1-quic_bqiang@quicinc.com>
 <20240227104427.7505-3-quic_bqiang@quicinc.com>
 <20240227121602.GM2587@thinkpad>
From: Baochen Qiang <quic_bqiang@quicinc.com>
In-Reply-To: <20240227121602.GM2587@thinkpad>
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On 2/27/2024 8:16 PM, Manivannan Sadhasivam wrote:
> On Tue, Feb 27, 2024 at 06:44:26PM +0800, Baochen Qiang wrote:
>> MHI devices may not be destroyed during suspend/hibernation, so need
>> to unprepare/prepare MHI channels throughout the transition, this is
>> done by adding suspend/resume callbacks.
>>
>> The suspend callback is called in the late suspend stage, this means
>> MHI channels are still alive at suspend stage, and that makes it
>> possible for an MHI controller driver to communicate with others over
>> those channels at suspend stage. While the resume callback is called
>> in the early resume stage, for a similar reason.
>>
>> Also note that we won't do unprepare/prepare when MHI device is in
>> suspend state because it's pointless if MHI is only meant to go through
>> a suspend/resume transition, instead of a complete power cycle.
>>
>> Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.30
>>
>> Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
> 
> Btw, you forgot to CC netdev folks. Here is the list that get_maintainer.pl
> returns:
> 
> "David S. Miller" <davem@davemloft.net> (maintainer:NETWORKING [GENERAL])
> Eric Dumazet <edumazet@google.com> (maintainer:NETWORKING [GENERAL])
> Jakub Kicinski <kuba@kernel.org> (maintainer:NETWORKING [GENERAL])
> Paolo Abeni <pabeni@redhat.com> (maintainer:NETWORKING [GENERAL])
> netdev@vger.kernel.org (open list:NETWORKING [GENERAL])
> 
Sure Mani, will send a v4 with above folks CC'ed.

> - Mani
> 
>> ---
>>   net/qrtr/mhi.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 46 insertions(+)
>>
>> diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c
>> index 9ced13c0627a..69f53625a049 100644
>> --- a/net/qrtr/mhi.c
>> +++ b/net/qrtr/mhi.c
>> @@ -118,6 +118,51 @@ static const struct mhi_device_id qcom_mhi_qrtr_id_table[] = {
>>   };
>>   MODULE_DEVICE_TABLE(mhi, qcom_mhi_qrtr_id_table);
>>   
>> +static int __maybe_unused qcom_mhi_qrtr_pm_suspend_late(struct device *dev)
>> +{
>> +	struct mhi_device *mhi_dev = container_of(dev, struct mhi_device, dev);
>> +	enum mhi_state state;
>> +
>> +	state = mhi_get_mhi_state(mhi_dev->mhi_cntrl);
>> +	/*
>> +	 * If the device is in suspend state, then no need for the
>> +	 * client driver to unprepare the channels.
>> +	 */
>> +	if (state == MHI_STATE_M3)
>> +		return 0;
>> +
>> +	mhi_unprepare_from_transfer(mhi_dev);
>> +
>> +	return 0;
>> +}
>> +
>> +static int __maybe_unused qcom_mhi_qrtr_pm_resume_early(struct device *dev)
>> +{
>> +	struct mhi_device *mhi_dev = container_of(dev, struct mhi_device, dev);
>> +	enum mhi_state state;
>> +	int rc;
>> +
>> +	state = mhi_get_mhi_state(mhi_dev->mhi_cntrl);
>> +	/*
>> +	 * If the device is in suspend state, we won't unprepare channels
>> +	 * in suspend callback, therefore no need to prepare channels when
>> +	 * resume.
>> +	 */
>> +	if (state == MHI_STATE_M3)
>> +		return 0;
>> +
>> +	rc = mhi_prepare_for_transfer_autoqueue(mhi_dev);
>> +	if (rc)
>> +		dev_err(dev, "failed to prepare for autoqueue transfer %d\n", rc);
>> +
>> +	return rc;
>> +}
>> +
>> +static const struct dev_pm_ops qcom_mhi_qrtr_pm_ops = {
>> +	SET_LATE_SYSTEM_SLEEP_PM_OPS(qcom_mhi_qrtr_pm_suspend_late,
>> +				     qcom_mhi_qrtr_pm_resume_early)
>> +};
>> +
>>   static struct mhi_driver qcom_mhi_qrtr_driver = {
>>   	.probe = qcom_mhi_qrtr_probe,
>>   	.remove = qcom_mhi_qrtr_remove,
>> @@ -126,6 +171,7 @@ static struct mhi_driver qcom_mhi_qrtr_driver = {
>>   	.id_table = qcom_mhi_qrtr_id_table,
>>   	.driver = {
>>   		.name = "qcom_mhi_qrtr",
>> +		.pm = &qcom_mhi_qrtr_pm_ops,
>>   	},
>>   };
>>   
>> -- 
>> 2.25.1
>>
>