Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Message-ID: <03ef297b35b87ed8f3c111cf7e67592b1c8e29a9.camel@sipsolutions.net>
Subject: Re: [PATCH 11/12] iwlwifi: pcie: remove TR/CR tail allocations
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Luca Coelho <luca@coelho.fi>, kvalo@codeaurora.org
Cc:     linux-wireless@vger.kernel.org
Date:   Thu, 17 Jun 2021 09:43:09 +0200
In-Reply-To: <iwlwifi.20210617100544.b5c639f3866f.I4d5de1929be048085767f1234a1e07b517ab6a2d@changeid> (sfid-20210617_091102_610763_E92F4BD5)
References: <20210617070852.496985-1-luca@coelho.fi>
         <iwlwifi.20210617100544.b5c639f3866f.I4d5de1929be048085767f1234a1e07b517ab6a2d@changeid>
         (sfid-20210617_091102_610763_E92F4BD5)
Content-Type: text/plain; charset="UTF-8"
User-Agent: Evolution 3.38.4 (3.38.4-1.fc33) 
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Thu, 2021-06-17 at 10:08 +0300, Luca Coelho wrote:
> From: Johannes Berg <johannes.berg@intel.com>
> 
> The TR/CR tail data are meant to be per-queue-arrays, however,
> we allocate them completely wrong (we have a separate allocation
> per queue).
> 
> Looking at this more closely, it turns out that the hardware
> never uses these - we have a separate free list per RX queue
> and maintain a write pointer for that in a register, and the
> RX itself is indicated in the RB status (rb_stts) DMA region.
> 
> Therefore, remove the TR/CR tail allocations completely.

I guess you should've updated the commit message when squashing in the
fix here - we do need to give it dummy pointers, and the hardware *does*
use them, just for no relevant purpose :)

johannes