Re: [PATCH] net: qrtr: resend HELLO on MHI resume

[Vlastimil Babka]

On 9/14/26 11:04, Thorsten Leemhuis wrote:
> On 9/9/26 07:58, Daniel J Blueman wrote:
>> Since the MHI HELLO exchange was relocated, it is sent only at device
>> registration. During a suspend-resume cycle, the firmware in WiFi
>> cards such as WCN7850 indefinitely waits for another HELLO,
>> triggering:
>> 
>>   ath12k_wifi7_pci 0004:01:00.0: timeout while waiting for restart complete
>>   ath12k_wifi7_pci 0004:01:00.0: failed to resume core: -110
>> 
>> Fix this by triggering the handshake from resume_early in the MHI
>> transport.
>> 
>> Validated on Qualcomm X1E-801800 on Lenovo Slim 7x across 10
>> suspend-resume cycles.
> 
> For the record: Takashi ran into this regression as well and provided a
> different fix, but withdrew it after I pointed out this fix, which
> worked for Takashi. For details see:
> https://lore.kernel.org/all/87mrtkpd2q.wl-tiwai@xxxxxxx/

Thanks to Thorsten pointing me there I skipped the bisect and applied this
patch instead and it works.

My laptop is T14s AMD Gen3 with ath11k_pci. Since rc2 the wifi would stop
working on suspend/resume, making the resume freeze for a while (I initially
thought it was frozen completely and was shutting off the laptop).

Interestingly the card doesn't recover after reboot, but only after a full
power off/on cycle. But if the HELLO handshake is sent after a boot,
shouldn't it recover? Maybe the hardware gets too confused to recover.
Dunno. Hm maybe I can try if 7.2 kernel (and/or 7.3 with this patch)
recovers it without poweroff/on after a 7.3 without this patch
suspend/resume wedges it.

But anyway this prevents the suspend/resume issue for me from happening in
the first place on 7.3-rc3, so:

Tested-by: Vlastimil Babka (SUSE) <vbabka@xxxxxxxxxx>

> 
> Ciao, Thorsten
>> Fixes: 544d85de4dc2 ("net: qrtr: Send HELLO message on endpoint register")
>> Signed-off-by: Daniel J Blueman <daniel@xxxxxxxxx>
>> ---
>>  net/qrtr/af_qrtr.c | 13 +++++++++++++
>>  net/qrtr/mhi.c     | 10 +++++++++-
>>  net/qrtr/qrtr.h    |  2 ++
>>  3 files changed, 24 insertions(+), 1 deletion(-)
>> 
>> diff --git a/net/qrtr/af_qrtr.c b/net/qrtr/af_qrtr.c
>> index 78347c937af7..2ffcfc2fdb4a 100644
>> --- a/net/qrtr/af_qrtr.c
>> +++ b/net/qrtr/af_qrtr.c
>> @@ -623,6 +623,19 @@ static void qrtr_hello_work(struct work_struct *work)
>>  	qrtr_port_put(ctrl);
>>  }
>>  
>> +/* Trigger the HELLO handshake after the remote has been reset, eg on resume */
>> +void qrtr_endpoint_hello(struct qrtr_endpoint *ep)
>> +{
>> +	struct qrtr_node *node = ep->node;
>> +
>> +	mutex_lock(&node->ep_lock);
>> +	node->hello_sent = false;
>> +	mutex_unlock(&node->ep_lock);
>> +
>> +	schedule_delayed_work(&node->say_hello, 0);
>> +}
>> +EXPORT_SYMBOL_GPL(qrtr_endpoint_hello);
>> +
>>  /**
>>   * qrtr_endpoint_register() - register a new endpoint
>>   * @ep: endpoint to register
>> diff --git a/net/qrtr/mhi.c b/net/qrtr/mhi.c
>> index 3990da1a65dc..50326ffa3401 100644
>> --- a/net/qrtr/mhi.c
>> +++ b/net/qrtr/mhi.c
>> @@ -183,6 +183,7 @@ static int __maybe_unused qcom_mhi_qrtr_pm_suspend_late(struct device *dev)
>>  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);
>> +	struct qrtr_mhi_dev *qdev = dev_get_drvdata(dev);
>>  	enum mhi_state state;
>>  	int rc;
>>  
>> @@ -201,7 +201,13 @@ static int __maybe_unused qcom_mhi_qrtr_pm_resume_early(struct device *dev)
>>  		return rc;
>>  	}
>>  
>> -	return qcom_mhi_qrtr_queue_dl_buffers(mhi_dev);
>> +	rc = qcom_mhi_qrtr_queue_dl_buffers(mhi_dev);
>> +	if (rc)
>> +		return rc;
>> +
>> +	qrtr_endpoint_hello(&qdev->ep);
>> +
>> +	return 0;
>>  }
>>  
>>  static const struct dev_pm_ops qcom_mhi_qrtr_pm_ops = {
>> diff --git a/net/qrtr/qrtr.h b/net/qrtr/qrtr.h
>> index 3f2d28696062..de2de69a6199 100644
>> --- a/net/qrtr/qrtr.h
>> +++ b/net/qrtr/qrtr.h
>> @@ -27,6 +27,8 @@ int qrtr_endpoint_register(struct qrtr_endpoint *ep, unsigned int nid);
>>  
>>  void qrtr_endpoint_unregister(struct qrtr_endpoint *ep);
>>  
>> +void qrtr_endpoint_hello(struct qrtr_endpoint *ep);
>> +
>>  int qrtr_endpoint_post(struct qrtr_endpoint *ep, const void *data, size_t len);
>>  
>>  int qrtr_ns_init(void);