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From:   Luca Coelho <luca@coelho.fi>
In-Reply-To: <iwlwifi.20210617110647.5f5764e04c46.I4d5de1929be048085767f1234a1e07b517ab6a2d@changeid>
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To:     Luca Coelho <luca@coelho.fi>
Cc:     kvalo@codeaurora.org, johannes@sipsolutions.net,
        linux-wireless@vger.kernel.org
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Message-Id: <E1lvfOf-001awB-EH@farmhouse.coelho.fi>
Date:   Tue, 22 Jun 2021 15:20:54 +0300
Subject: Re: [PATCH v2 11/12] iwlwifi: pcie: remove TR/CR tail allocations
Precedence: bulk

Luca Coelho <luca@coelho.fi> 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.
> 
> Despite nothing using the tail pointers, the hardware will
> unconditionally access them to write updates, even when we aren't
> using CRs/TRs.
> 
> Give it dummy values that we never use/update so it can do that
> without causing trouble.
> 
> Signed-off-by: Johannes Berg <johannes.berg@intel.com>
> Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

Patch applied to iwlwifi-next.git, thanks.

a5575a54df00 iwlwifi: pcie: remove TR/CR tail allocations