Re: [PATCH] rpmsg: glink: Split protocol start out of native_probe

[Chunkai Deng <chunkai.deng@oss.qualcomm.com>]

On 6/29/2026 8:47 PM, Konrad Dybcio wrote:

> On 6/19/26 7:01 AM, Chunkai Deng wrote:
>> The SMEM and RPM transports request their receive interrupt with
>> IRQF_NO_AUTOEN and enable it only after qcom_glink_native_probe()
>> returns. Since native_probe() sends the initial version command, the
>> remote may ACK before the local IRQ is enabled, stalling the version
>> handshake on a fast remote.
>>
>> Split the protocol start (qcom_glink_send_version() and
>> qcom_glink_create_chrdev()) into a new qcom_glink_native_start().
>> Transports now enable their IRQ first, then call native_start(), so the
>> version ACK is guaranteed to be serviced.
>>
>> Signed-off-by: Chunkai Deng <chunkai.deng@oss.qualcomm.com>
>> ---
> Would it not be simpler to just move the devm_request_irq a bit down
> and remove the NO_AUTOEN flag then?

Thanks for the suggestion.
I analyzed and verified it locally,but I'd personally still lean towards
keeping the current change as-is. My reasoning:

(1) The IRQ must be live before the version handshake — that's the core
point that can't change. The version command is sent from native_start(),
so we need to request/enable the IRQ first and only then call
native_start(). That ordering is only possible with the version send
kept out of native_probe(), so the split needs to stay.

(2) Dropping IRQF_NO_AUTOEN does make the structure a little simpler,
and functionally it's equivalent, but I'd lean towards keeping the
request-disabled + explicit enable_irq() form. It makes the ordering
constraint visible at the call site: the IRQ is requested up front,
and enable_irq() marks the exact point where the handler becomes safe
to run(glink assigned) and where we want RX servicing to begin. Folding
that into an implicit auto-enable hides that intent, and I think the
explicit form is easier to maintain.

That said, if you'd prefer the simpler form, I'm happy to do the IRQ
cleanup as a separate follow-up patch on top of this fix rather than
mixing the refactor into the race fix.

Best regards,
Chunkai Deng