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From:   Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>
To:     Wen Gong <wgong@qti.qualcomm.com>, Wen Gong <wgong@codeaurora.org>,
        "ath10k\@lists.infradead.org" <ath10k@lists.infradead.org>
Cc:     "linux-wireless\@vger.kernel.org" <linux-wireless@vger.kernel.org>
Subject: RE: [PATCH 4/7] ath10k: disable TX complete indication of htt for sdio
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Date:   Wed, 21 Aug 2019 12:10:27 +0200
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Wen Gong <wgong@qti.qualcomm.com> writes:

>> -----Original Message-----
>> From: ath10k <ath10k-bounces@lists.infradead.org> On Behalf Of Toke
>> Høiland-Jørgensen
>> Sent: Tuesday, August 20, 2019 8:24 PM
>> To: Wen Gong <wgong@codeaurora.org>; ath10k@lists.infradead.org
>> Cc: linux-wireless@vger.kernel.org
>> Subject: [EXT] Re: [PATCH 4/7] ath10k: disable TX complete indication of htt
>> for sdio
>> 
>> Wen Gong <wgong@codeaurora.org> writes:
>> 
>> > Tx complete message from firmware cost bus bandwidth of sdio, and bus
>> > bandwidth is the bollteneck of throughput, it will effect the bandwidth
>> > occupancy of data packet of TX and RX.
>> >
>> > This patch disable TX complete indication from firmware for htt data
>> > packet, it results in significant performance improvement on TX path.
>> 
>> Wait, how does that work? Am I understanding it correctly that this
>> replaces a per-packet TX completion with a periodic one sent out of
>> band?
> When this patch applied, firmware will not indicate tx complete for tx
> Data, it only indicate HTT_T2H_MSG_TYPE_TX_CREDIT_UPDATE_IND,
> This htt msg will tell how many data tx complete without status(status maybe success/fail).

Ah, so this is basically a counter of how much data is currently queued
in the firmware?

>> And could you explain what the credits thing is for, please? :)
> For high latency bus chip, all the tx data's content(include ip/udp/tcp header
> and payload) will be transfer to firmware's memory via bus.
> And firmware has limited memory for tx data, the tx data's content must
> Saved in firmware memory before it tx complete, if ath10k transfer tx
> data more than the limit, firmware will occur error. The credit is used
> to avoid ath10k exceed the limit.

What's a typical limit in the firmware?

-Toke