Re: [PATCH 2/3] ufs: core: Introduce ufshcd_mcq_poll_cqe_lock_n()

[Bart Van Assche <bvanassche@acm.org>]

On 3/31/26 2:43 AM, Peter Wang (王信友) wrote:
> On Mon, 2026-03-30 at 11:33 -0700, Bart Van Assche wrote:
>> Introduce a new function for processing completions and that accepts
>> an
>> upper limit for the number of completions to poll. Tell
>> ufshcd_mcq_poll_cqe_lock() to poll at most hwq->max_entries. This is
>> sufficient to poll all pending completions since there are never more
>> than hwq->max_entries - 1 completions on a completion queue. This
>> patch
>> prepares for reducing the interrupt latency.
> 
> Could it be more than (hwq->max_entries - 1) if the host keeps
> sending requests to the same hardware queue from different CPU cores?

No, because the completion queue head is read before processing
completion queue entries starts. No matter how many completions are
pushed onto the completion queue while ufshcd_mcq_poll_cqe_lock() is
in progress, it won't process more than (hwq->max_entries - 1) because
that's the maximum difference between the tail and the head pointers.

Thanks,

Bart.