linux-kernel - Re: [PATCH 4.14 04/40] Bluetooth: btqca: Add a short delay before downloading the NVM

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Date:   Mon, 9 Sep 2019 09:13:59 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Marcel Holtmann <marcel@...tmann.org>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 4.14 04/40] Bluetooth: btqca: Add a short delay before
 downloading the NVM

On Sun, Sep 08, 2019 at 01:41:37PM +0100, Greg Kroah-Hartman wrote:
> [ Upstream commit 8059ba0bd0e4694e51c2ee6438a77b325f06c0d5 ]
> 
> On WCN3990 downloading the NVM sometimes fails with a "TLV response
> size mismatch" error:
> 
> [  174.949955] Bluetooth: btqca.c:qca_download_firmware() hci0: QCA Downloading qca/crnv21.bin
> [  174.958718] Bluetooth: btqca.c:qca_tlv_send_segment() hci0: QCA TLV response size mismatch

WC3990 support was only added in 4.19, so this shouldn't be needed in
older kernels, but it shouldn't do any harm either ;-)

> It seems the controller needs a short time after downloading the
> firmware before it is ready for the NVM. A delay as short as 1 ms
> seems sufficient, make it 10 ms just in case. No event is received
> during the delay, hence we don't just silently drop an extra event.
> 
> Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> Signed-off-by: Marcel Holtmann <marcel@...tmann.org>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>  drivers/bluetooth/btqca.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/bluetooth/btqca.c b/drivers/bluetooth/btqca.c
> index 0bbdfcef2aa84..a48a61f22f823 100644
> --- a/drivers/bluetooth/btqca.c
> +++ b/drivers/bluetooth/btqca.c
> @@ -363,6 +363,9 @@ int qca_uart_setup_rome(struct hci_dev *hdev, uint8_t baudrate)
>  		return err;
>  	}
>  
> +	/* Give the controller some time to get ready to receive the NVM */
> +	msleep(10);
> +
>  	/* Download NVM configuration */
>  	config.type = TLV_TYPE_NVM;
>  	snprintf(config.fwname, sizeof(config.fwname), "qca/nvm_%08x.bin",