From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A91D9C433F5 for ; Fri, 17 Sep 2021 12:41:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8C4E860F6D for ; Fri, 17 Sep 2021 12:41:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233669AbhIQMnN (ORCPT ); Fri, 17 Sep 2021 08:43:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39698 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232100AbhIQMnN (ORCPT ); Fri, 17 Sep 2021 08:43:13 -0400 Received: from mout-p-102.mailbox.org (mout-p-102.mailbox.org [IPv6:2001:67c:2050::465:102]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 18845C061574; Fri, 17 Sep 2021 05:41:51 -0700 (PDT) Received: from smtp2.mailbox.org (smtp2.mailbox.org [80.241.60.241]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-384) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-102.mailbox.org (Postfix) with ESMTPS id 4H9tqx4HwtzQkBK; Fri, 17 Sep 2021 14:41:49 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Subject: Re: [PATCH] Bluetooth: btusb: Lower passive lescan interval on Marvell 88W8897 To: Marcel Holtmann Cc: Amitkumar Karwar , Ganapathi Bhat , Xinming Hu , Kalle Valo , "David S. Miller" , Jakub Kicinski , Johan Hedberg , Luiz Augusto von Dentz , Tsuchiya Yuto , linux-wireless@vger.kernel.org, linux-bluetooth , open list , Maximilian Luz , Andy Shevchenko , =?UTF-8?Q?Pali_Roh=c3=a1r?= References: <20210917122718.86776-1-verdre@v0yd.nl> From: =?UTF-8?Q?Jonas_Dre=c3=9fler?= Message-ID: <3e5b7e27-e643-ae9b-db40-d885ca441385@v0yd.nl> Date: Fri, 17 Sep 2021 14:41:42 +0200 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 5493A1848 Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On 9/17/21 2:35 PM, Marcel Holtmann wrote: > Hi Jonas, > >> The Marvell 88W8897 combined wifi and bluetooth card (pcie+usb version) >> is used in a lot of Microsoft Surface devices, and all those devices >> suffer from very low 2.4GHz wifi connection speeds while bluetooth is >> enabled. The reason for that is that the default passive scanning >> interval for Bluetooth Low Energy devices is quite high on Linux >> (interval of 60 msec and scan window of 30 msec, see le_scan_interval >> and le_scan_window in hci_core.c), and the Marvell chip is known for its >> bad bt+wifi coexisting performance. >> >> So decrease that passive scan interval and make the scan window shorter >> on this particular device to allow for spending more time transmitting >> wifi signals: The new scan interval is 250 msec (0x190 * 0.625 msec) and >> the new scan window is 6.25 msec (0xa * 0.625 msec). >> >> This change has a very large impact on the 2.4GHz wifi speeds and gets >> it up to performance comparable with the Windows driver, which seems to >> apply a similar quirk. >> >> The scan interval and scan window length were tested and found to work >> very well with a bunch of Bluetooth Low Energy devices, including the >> Surface Pen, a Bluetooth Speaker and two modern Bluetooth headphones. >> All devices were discovered immediately after turning them on. Even >> lower values were also tested, but these introduced longer delays until >> devices get discovered. >> >> Signed-off-by: Jonas Dreßler >> --- >> drivers/bluetooth/btusb.c | 15 +++++++++++++++ >> 1 file changed, 15 insertions(+) >> >> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c >> index 60d2fce59a71..05b11179c839 100644 >> --- a/drivers/bluetooth/btusb.c >> +++ b/drivers/bluetooth/btusb.c >> @@ -59,6 +59,7 @@ static struct usb_driver btusb_driver; >> #define BTUSB_WIDEBAND_SPEECH 0x400000 >> #define BTUSB_VALID_LE_STATES 0x800000 >> #define BTUSB_QCA_WCN6855 0x1000000 >> +#define BTUSB_LOWER_LESCAN_INTERVAL 0x2000000 >> #define BTUSB_INTEL_BROKEN_INITIAL_NCMD 0x4000000 >> >> static const struct usb_device_id btusb_table[] = { >> @@ -356,6 +357,7 @@ static const struct usb_device_id blacklist_table[] = { >> { USB_DEVICE(0x1286, 0x2044), .driver_info = BTUSB_MARVELL }, >> { USB_DEVICE(0x1286, 0x2046), .driver_info = BTUSB_MARVELL }, >> { USB_DEVICE(0x1286, 0x204e), .driver_info = BTUSB_MARVELL }, >> + { USB_DEVICE(0x1286, 0x204c), .driver_info = BTUSB_LOWER_LESCAN_INTERVAL }, >> >> /* Intel Bluetooth devices */ >> { USB_DEVICE(0x8087, 0x0025), .driver_info = BTUSB_INTEL_COMBINED }, >> @@ -3813,6 +3815,19 @@ static int btusb_probe(struct usb_interface *intf, >> if (id->driver_info & BTUSB_MARVELL) >> hdev->set_bdaddr = btusb_set_bdaddr_marvell; >> >> + /* The Marvell 88W8897 combined wifi and bluetooth card is known for >> + * very bad bt+wifi coexisting performance. >> + * >> + * Decrease the passive BT Low Energy scan interval a bit >> + * (0x0190 * 0.625 msec = 250 msec) and make the scan window shorter >> + * (0x000a * 0,625 msec = 6.25 msec). This allows for significantly >> + * higher wifi throughput while passively scanning for BT LE devices. >> + */ >> + if (id->driver_info & BTUSB_LOWER_LESCAN_INTERVAL) { >> + hdev->le_scan_interval = 0x0190; >> + hdev->le_scan_window = 0x000a; >> + } >> + > > you can not do it this way. Modifying hci_dev internals from within the driver is not acceptable. > > Regards > > Marcel > Hi Marcel, hmm okay, it seems to me that the intention of your commit bef64738e3fb87eabc6fbeededad0c44ea173384 was to allow configuring it on a per controller basis, also btusb changes a bunch of other hci_dev properties? Given that we also have to match by usb-id, I don't think there's another place to do that other than the usb driver, or is there? Jonas