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

["Vlastimil Babka (SUSE)" <vbabka@kernel.org>]

On 9/15/26 12:11, Vlastimil Babka wrote:
> 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@suse.de/
> 
> 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.

Neither 7.2 nor 7.3 + patch was able to recover the card on reboot, so while
that's not great, at least 7.3+patch isn't worse in this aspect.