linux-kernel - INTMS/INTMC not being used in NVME interrupt handling

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Date:   Wed, 16 May 2018 12:35:15 +0000
From:   Bharat Kumar Gogada <bharatku@...inx.com>
To:     "linux-nvme@...ts.infradead.org" <linux-nvme@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "keith.busch@...el.com" <keith.busch@...el.com>,
        "axboe@...com" <axboe@...com>, "hch@....de" <hch@....de>,
        "sagi@...mberg.me" <sagi@...mberg.me>
Subject: INTMS/INTMC not being used in NVME interrupt handling

Hi,

As per NVME specification: 
7.5.1.1 Host Software Interrupt Handling
It is recommended that host software utilize the Interrupt Mask Set and Interrupt Mask Clear (INTMS/INTMC) 
registers to efficiently handle interrupts when configured to use pin based or MSI messages.

In kernel 4.14, drivers/nvme/host/pci.c function nvme_isr 
doesn't  use these registers. 

Any reason why these registers are not used in nvme interrupt handler ?

Why NVMe driver is not using any bottom half and processing all completion queues
in interrupt handler ?

Regards,
Bharat