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Message-ID: <ef427b87-1cf2-4ae2-8f14-2e2b34df3d84@quicinc.com>
Date: Mon, 4 Mar 2024 10:01:56 +0800
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Subject: Re: [PATCH v4 1/3] bus: mhi: host: add mhi_power_down_keep_dev()
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To: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
CC: Kalle Valo <kvalo@kernel.org>,
        "Kalle Valo (QUIC)"
	<quic_kvalo@quicinc.com>,
        <ath11k@lists.infradead.org>, <linux-wireless@vger.kernel.org>,
        <linux-arm-msm@vger.kernel.org>, <mhi@lists.linux.dev>,
        <davem@davemloft.net>, <edumazet@google.com>, <kuba@kernel.org>,
        <pabeni@redhat.com>, <netdev@vger.kernel.org>
References: <20240228022243.17762-1-quic_bqiang@quicinc.com>
 <20240228022243.17762-2-quic_bqiang@quicinc.com>
 <20240229101202.GB2999@thinkpad>
 <531daaa9-cf14-4812-8908-c617bd25bc08@quicinc.com>
 <87le7383nd.fsf@kernel.org>
 <b5b3f46d-ad98-44e5-84e0-7b00fe29ec5a@quicinc.com>
 <20240301122559.GB2401@thinkpad>
From: Baochen Qiang <quic_bqiang@quicinc.com>
In-Reply-To: <20240301122559.GB2401@thinkpad>
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On 3/1/2024 8:25 PM, Manivannan Sadhasivam wrote:
> On Fri, Mar 01, 2024 at 10:04:06AM +0800, Baochen Qiang wrote:
>>
>>
>> On 3/1/2024 3:35 AM, Kalle Valo wrote:
>>> Baochen Qiang <quic_bqiang@quicinc.com> writes:
>>>
>>>> On 2/29/2024 6:12 PM, Manivannan Sadhasivam wrote:
>>>>> On Wed, Feb 28, 2024 at 10:22:41AM +0800, Baochen Qiang wrote:
>>>>>> ath11k fails to resume:
>>>>>>
>>>>>> ath11k_pci 0000:06:00.0: timeout while waiting for restart complete
>>>>>>
>>>>>> This happens because when calling mhi_sync_power_up() the MHI subsystem
>>>>>> eventually calls device_add() from mhi_create_devices() but the device
>>>>>> creation is deferred:
>>>>>>
>>>>>> mhi mhi0_IPCR: Driver qcom_mhi_qrtr force probe deferral
>>>>>>
>>>>>> The reason for deferring device creation is explained in dpm_prepare():
>>>>>>
>>>>>>            /*
>>>>>>             * It is unsafe if probing of devices will happen during suspend or
>>>>>>             * hibernation and system behavior will be unpredictable in this case.
>>>>>>             * So, let's prohibit device's probing here and defer their probes
>>>>>>             * instead. The normal behavior will be restored in dpm_complete().
>>>>>>             */
>>>>>>
>>>>>> Because the device probe is deferred, the qcom_mhi_qrtr_probe() is not
>>>>>> called and thus MHI channels are not prepared:
>>>>>>
>>>>>> So what this means that QRTR is not delivering messages and the QMI connection
>>>>>> is not working between ath11k and the firmware, resulting a failure in firmware
>>>>>> initialization.
>>>>>>
>>>>>> To fix this add new function mhi_power_down_keep_dev() which doesn't destroy
>>>>>> the devices for channels during power down. This way we avoid probe defer issue
>>>>>> and finally can get ath11k hibernation working with the following patches.
>>>>>>
>>>>>> Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.30
>>>>>>
>>>>>> Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
>>>>>
>>>>> Did Kalle co-author this patch? If so, his Co-developed-by tag should
>>>>> be added.
>>>>
>>>> Hmm, I'm not sure...  I would like Kalle's thoughts on this.
>>>
>>> IIRC I did only some simple cleanup before submitting the patch so I
>>> don't think Co-developed-by is justified. I'm also fine with removing my
>>> Signed-off-by.
>> Thanks Kalle.
>>
>> Hi Mani, so according to Kalle's comments, I'd like to keep the patch as is.
>>
> 
> No. Either remove his signed off by (as indicated by Kalle) or add a
> co-developed-by tag. Keeping just a signed-off-by tag is wrong.
> 
OK, will send new version with Kalle's s-o-b tag removed.

> - Mani
>