Re: [PATCH v2] net: mvneta: free/request IRQ across suspend/resume

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

Hi,

On 6/17/26 11:20, Yun Zhou wrote:
> On PREEMPT_RT, the mvneta IRQ handler is force-threaded. Under high
> network traffic, the IRQ can enter suspend with desc->depth == 1
> (masked by the oneshot mechanism between handler invocations).
> 
> During suspend, the kernel increments depth to 2 and masks the
> interrupt at the MPIC level (clearing the SRC_CTL CPU routing bit,
> due to IRQCHIP_MASK_ON_SUSPEND). On resume, depth is decremented
> back to 1, but since it does not reach 0, the unmask is never
> called. The MPIC CPU routing remains cleared, permanently disabling
> interrupt delivery.
> 
> Fix by freeing the IRQ in suspend and re-requesting it in resume.
> This ensures a clean IRQ state (depth=0, proper hardware routing)
> on every resume cycle, regardless of the pre-suspend depth. This
> follows the approach used by other drivers (e.g. igb).

This description makes it sound like it's not really a mvneta problem,
but rather a broader effect from  preempt-rt / irq management / suspend
interactions.

Is this the expected way to deal with that ?

Maxime