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From:   Fabio Estevam <festevam@gmail.com>
Date:   Wed, 18 Aug 2021 18:09:01 -0300
Message-ID: <CAOMZO5DQTArbXjAdxh4cmtwPfRS9UCiAiQeRQHhjqLpEOUxsyA@mail.gmail.com>
Subject: Re: [PATCH] ath10k: Do not call dma_alloc_coherent() for SDIO and USB
To:     Peter Oh <peter.oh@eero.com>
Cc:     Arend van Spriel <aspriel@gmail.com>,
        Fabio Estevam <festevam@denx.de>,
        Kalle Valo <kvalo@codeaurora.org>, ath10k@lists.infradead.org,
        linux-wireless <linux-wireless@vger.kernel.org>,
        Christoph Hellwig <hch@lst.de>, erik.stromdahl@gmail.com
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Hi Peter,

On Wed, Aug 18, 2021 at 2:35 PM Peter Oh <peter.oh@eero.com> wrote:
>
>
> >> Fix the problem by not calling dma_alloc_coherent() when the device
> >> is not DMA capable, such as SDIO and USB.
> >>
> ath10k calls dma_alloc_coherent multiple places including
> ath10k_htt_rx_alloc.
>
> Do SDIO and USB not use such data path function at all?

Now that I look closer:  no, SDIO and USB do not reach the
dma_alloc_coherent() inside
ath10k_htt_rx_alloc.

drivers/net/wireless/ath/ath10k/usb.c and
drivers/net/wireless/ath/ath10k/sdio.c both set:
bus_params.dev_type = ATH10K_DEV_TYPE_HL;

ath10k_htt_rx_alloc() has:

if (ar->bus_param.dev_type == ATH10K_DEV_TYPE_HL)
     return 0;

So it returns early in the USB and SDIO cases and does not call
dma_alloc_coherent().

Thanks