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spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389386AbeHPK2m (ORCPT ); Thu, 16 Aug 2018 06:28:42 -0400 Received: from fllv0016.ext.ti.com ([198.47.19.142]:36984 "EHLO fllv0016.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730053AbeHPK2m (ORCPT ); Thu, 16 Aug 2018 06:28:42 -0400 Received: from dlelxv90.itg.ti.com ([172.17.2.17]) by fllv0016.ext.ti.com (8.15.2/8.15.2) with ESMTP id w7G7Vken048198; Thu, 16 Aug 2018 02:31:46 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1534404706; bh=dpt4A8mVBtbw2c31lFJ4H4ZnB+7mTYqQNVK8X57A5S0=; h=Subject:To:CC:References:From:Date:In-Reply-To; b=YsaS2FHlKeqCggheOGRiEAEEbY5aUFSWvWVlJRMtAnqqHk9vXuRdxOsMvL2bOg4zQ VUKv4k/cqJG+RBffR9gA0Dgm+DA3nFbdvWnpWKDRuxtrKiCecM/OOOVlUSNUexEhea fVnQHOcn5uUWp70wX1PSb7dyt5Yf/XinPVBw/oEg= Received: from DFLE112.ent.ti.com (dfle112.ent.ti.com [10.64.6.33]) by dlelxv90.itg.ti.com (8.14.3/8.13.8) with ESMTP id w7G7Vkqk013496; Thu, 16 Aug 2018 02:31:46 -0500 Received: from DFLE105.ent.ti.com (10.64.6.26) by DFLE112.ent.ti.com (10.64.6.33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1466.3; Thu, 16 Aug 2018 02:31:45 -0500 Received: from dlep32.itg.ti.com (157.170.170.100) by DFLE105.ent.ti.com (10.64.6.26) with Microsoft SMTP Server (version=TLS1_0, cipher=TLS_RSA_WITH_AES_256_CBC_SHA) id 15.1.1466.3 via Frontend Transport; Thu, 16 Aug 2018 02:31:46 -0500 Received: from [192.168.2.6] (ileax41-snat.itg.ti.com [10.172.224.153]) by dlep32.itg.ti.com (8.14.3/8.13.8) with ESMTP id w7G7VgYN002159; Thu, 16 Aug 2018 02:31:43 -0500 Subject: Re: [PATCH] usb: hub: try old enumeration scheme first for high speed devices To: "Zengtao (B)" , "gregkh@linuxfoundation.org" , "stern@rowland.harvard.edu" , "mathias.nyman@linux.intel.com" , "drinkcat@chromium.org" , "felipe.balbi@linux.intel.com" , "drake@endlessm.com" , "mike.looijmans@topic.nl" , "joe@perches.com" CC: "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" References: <1533913304-15737-1-git-send-email-prime.zeng@hisilicon.com> <678F3D1BB717D949B966B68EAEB446ED0C9B129B@dggemm526-mbx.china.huawei.com> From: Roger Quadros Openpgp: preference=signencrypt Autocrypt: addr=rogerq@ti.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <678F3D1BB717D949B966B68EAEB446ED0C9B129B@dggemm526-mbx.china.huawei.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-GB Content-Transfer-Encoding: 8bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14/08/18 10:33, Zengtao (B) wrote: > Hi Roger: > > Thank you for review > >> -----Original Message----- >> From: Roger Quadros [mailto:rogerq@ti.com] >> Sent: Friday, August 10, 2018 6:51 PM >> To: Zengtao (B) ; gregkh@linuxfoundation.org; >> stern@rowland.harvard.edu; mathias.nyman@linux.intel.com; >> drinkcat@chromium.org; felipe.balbi@linux.intel.com; drake@endlessm.com; >> mike.looijmans@topic.nl; joe@perches.com >> Cc: linux-usb@vger.kernel.org; linux-kernel@vger.kernel.org >> Subject: Re: [PATCH] usb: hub: try old enumeration scheme first for high speed >> devices >> >> Hi, >> >> On 10/08/18 18:01, Zeng Tao wrote: >>> The new scheme is required just to support legacy low and full-speed >>> devices. For high speed devices, it will slower the enumeration speed. >>> So in this patch we try the "old" enumeration scheme first for high >>> speed devices. >> >> How slow does it get? Is it significant? >> Do we risk breaking existing HS devices that work? I don't think we can be sure >> till we run this through testing. >> > > We added the new scheme because this is what the windows did , and mainly for > legacy low and full speed devices. > Now for new windows version(8.1 and later), the second port reset has already been > removed for high speed devices for better enumeration speed. > And In this patch if use_both_schemes is true, it will fallback to new scheme if the old > scheme fails. > > So I think it's reasonable to follow the windows behavior again. > >>> >>> Signed-off-by: Zeng Tao >>> --- >>> drivers/usb/core/hub.c | 5 ++++- >>> 1 file changed, 4 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index >>> 1fb2668..d265b19 100644 >>> --- a/drivers/usb/core/hub.c >>> +++ b/drivers/usb/core/hub.c >>> @@ -2661,10 +2661,13 @@ static bool use_new_scheme(struct usb_device >> *udev, int retry, >>> int old_scheme_first_port = >>> port_dev->quirks & USB_PORT_QUIRK_OLD_SCHEME; >>> >>> + int quick_enumeration = (udev->speed == USB_SPEED_HIGH); >>> + >>> if (udev->speed >= USB_SPEED_SUPER) >>> return false; >> >> how about replacing the above if with >> >> if (udev->speed >= USB_SPEED_HIGH) >> return false; > > No, for SS device, only use old scheme, but for speed device, we can fallback to new > scheme if the old fails. You are correct. > >>> >>> - return USE_NEW_SCHEME(retry, old_scheme_first_port || >> old_scheme_first); >>> + return USE_NEW_SCHEME(retry, old_scheme_first_port || >> old_scheme_first >>> + || quick_enumeration); >>> } >> >> Now we no longer respect the "old_scheme_first" parameter for most of the >> devices. >> >> It should be clarified in Documentation/admin/kernel-parameters.txt that >> "old_scheme_first" is only applicable to LOW/FULL speed devices. >> > > On the contrary, new scheme is only applicable for LOW/FULL speed devices? No. What I meant is that the "old_scheme_first" module parameter is now only applicable for LOW/FULL speed devices. As HIGH_SPEED devices will always use old scheme first after this patch. cheers, -roger -- Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki