netdev - Re: [PATCH v2 1/3] Bluetooth: btintel: Add firmware lock function

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Message-Id: <7CE1949F-76D2-4D27-82B6-02124E62DF5C@holtmann.org>
Date:   Wed, 17 Jul 2019 15:36:50 +0200
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc:     Johannes Berg <johannes.berg@...el.com>,
        emmanuel.grumbach@...el.com, luciano.coelho@...el.com,
        Johan Hedberg <johan.hedberg@...il.com>, linuxwifi@...el.com,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] Bluetooth: btintel: Add firmware lock function

Hi Kai-Heng,

> When Intel 8260 starts to load Bluetooth firmware and WiFi firmware, by
> calling btintel_download_firmware() and iwl_pcie_load_given_ucode_8000()
> respectively, the Bluetooth btintel_download_firmware() aborts half way:
> [   11.950216] Bluetooth: hci0: Failed to send firmware data (-38)
> 
> Let btusb and iwlwifi load firmwares exclusively can avoid the issue, so
> introduce a lock to use in btusb and iwlwifi.
> 
> This issue still occurs with latest WiFi and Bluetooth firmwares.
> 
> BugLink: https://bugs.launchpad.net/bugs/1832988
> 
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> ---
> v2:
> - Add bug report link.
> - Rebase on latest wireless-next.
> 
> drivers/bluetooth/btintel.c   | 14 ++++++++++++++
> drivers/bluetooth/btintel.h   | 10 ++++++++++
> include/linux/intel-wifi-bt.h |  8 ++++++++
> 3 files changed, 32 insertions(+)
> create mode 100644 include/linux/intel-wifi-bt.h
> 
> diff --git a/drivers/bluetooth/btintel.c b/drivers/bluetooth/btintel.c
> index bb99c8653aab..93ab18d6ddad 100644
> --- a/drivers/bluetooth/btintel.c
> +++ b/drivers/bluetooth/btintel.c
> @@ -20,6 +20,8 @@
> 
> #define BDADDR_INTEL (&(bdaddr_t) {{0x00, 0x8b, 0x9e, 0x19, 0x03, 0x00}})
> 
> +static DEFINE_MUTEX(firmware_lock);
> +
> int btintel_check_bdaddr(struct hci_dev *hdev)
> {
> 	struct hci_rp_read_bd_addr *bda;
> @@ -709,6 +711,18 @@ int btintel_download_firmware(struct hci_dev *hdev, const struct firmware *fw,
> }
> EXPORT_SYMBOL_GPL(btintel_download_firmware);
> 
> +void btintel_firmware_lock(void)
> +{
> +	mutex_lock(&firmware_lock);
> +}
> +EXPORT_SYMBOL_GPL(btintel_firmware_lock);
> +
> +void btintel_firmware_unlock(void)
> +{
> +	mutex_unlock(&firmware_lock);
> +}
> +EXPORT_SYMBOL_GPL(btintel_firmware_unlock);
> +

so I am not in favor of this solution. The hardware guys should start looking into fixing the firmware loading and provide proper firmware that can be loaded at the same time.

I am also not for sure penalizing all Intel Bluetooth/WiFi combos only because one of them has a bug during simultaneous loading of WiFi and Bluetooth firmware.

Frankly it would be better to detect a failed load and try a second time instead of trying to lock each other out. The cross-contamination of WiFi and Bluetooth drivers is just not clean.

Regards

Marcel