From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Subject: [v2] usb: serial: defer URB submission for ftdi_sio From: Johan Hovold Message-Id: <20190415080058.GA29656@localhost> Date: Mon, 15 Apr 2019 10:00:58 +0200 To: "Ramachandran Srinivasan \(BRT-SG\)" Cc: Johan Hovold , Greg Kroah-Hartman , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" List-ID: T24gVHVlLCBBcHIgMDksIDIwMTkgYXQgMTA6NDc6NDJBTSArMDAwMCwgUmFtYWNoYW5kcmFuIFNy aW5pdmFzYW4gKEJSVC1TRykgd3JvdGU6Cj4gRnJvbTogU3Jpbml2YXNhbiBSIDxzcmluaXZhc2Fu LnJAYnJ0Y2hpcC5jb20+Cj4gCj4gRGVmZXJyaW5nIHRoZSBVUkIgcmVzdWJtaXNzaW9uLCB0aGlz IGNhbiBoZWxwIHRpbWUgc2hhcmUgdGhlIGF2YWlsYWJsZQo+IERNQSBjaGFuZWxzIG9mIERXQ19P VEcgaG9zdCBjb250cm9sbGVyIGluIFJhc3BiZXJyeVBpLlRoaXMgY2hhbmdlIGNhbgo+IGZpeCB0 aGUgcHJvYmxlbSwgZmFpbGVkIHRvIGVudW1lcmF0ZSB0aGUgVVNCIGRldmljZSB3aGVuIGFsbCB0 aGUgOAo+IGluc3RhbmNlIG9mIGZ0ZGlfc2lvIHNlcmlhbCBkcml2ZXIgaXMgb3BlbiBieSBhcHBs aWNhdGlvbi4gbWFueSBidWdzCj4gaGFkIGJlZW4gcmFzaWVkIGZvciBSYXNwYmVycnlQaSBhcm91 bmQgdGhpcyBwcm9ibGVtIGNhbiBiZSBzb2x2ZWQKClRoYW5rcyBmb3IgcmVzZW5kaW5nIHdpdGgg YSBjb21taXQgbWVzc2FnZS4gWW91ciBwYXRjaCBpcyBzdGlsbAp3aGl0ZS1zcGFjZSBkYW1hZ2Vk IChjaGVjayB5b3VyIG1haWwgc2V0dXAsIGFuZCBtYWtlIHN1cmUgeW91IGNhbiBzZW5kIGEKcGF0 Y2ggdG8geW91cnNlbGYgYW5kIGFwcGx5IGl0IHdpdGggZ2l0IGFtKSwgYnV0IHdpdGggdGhlIGFi b3ZlCmRlc2NyaXB0aW9uIEkgdGhpbmsgSSBjYW4gZ2l2ZSBzb21lIGZlZWRiYWNrIGFscmVhZHku CgpGaXJzdCBvZiBhbGwsIGlmIHRoZXJlJ3MgYSBwcm9ibGVtIGhlcmUsIGl0IHdvdWxkIG5lZWQg dG8gYmUgZml4ZWQgaW4KdGhlIGhvc3QtY29udHJvbGxlciBkcml2ZXIgb2YgdGhlIHJwaSBhcyB3 ZSBkb24ndCB3YW50IHRvIGFkZAp3b3JrYXJvdW5kcyBmb3IgaG9zdC1jb250cm9sbGVyIGlzc3Vl cyB0byBldmVyeSBVU0IgZHJpdmVyLgoKSSBzdWdnZXN0IHlvdSB3cml0ZSB1cCBhbiBldmVuIG1v cmUgZGV0YWlsZWQgYnVnIHJlcG9ydCBkZXNjcmliaW5nIHRoZQpwcm9ibGVtIHlvdSdyZSBzZWVp bmcgYW5kIHNlbmQgaXQgdG8gdGhlIGxpc3QuCgpNZWFud2hpbGUsIHlvdSBjYW4gdHJ5IGluY3Jl YXNpbmcgdGhlIGxhdGVuY3kgdGltZXIgb2YgdGhlIGNvbm5lY3RlZApmdGRpIGRldmljZXMgdG8g cmVkdWNlIHRoZSBhbW91bnQgb2YgdHJhZmZpYyB0aGV5IGdlbmVyYXRlIHdoZW4gdGhleSdyZQpv dGhlcndpc2UgaWRsZSAoMTYgbXMgZGVmYXVsdCwgY2FuIGJlIGluY3JlYXNlZCB1cCB0byAyNTUg bXMgSSB0aGluaykuClRoYXQgbWF5IHBvc3NpYmx5IGFsbG93IHlvdSB0byBwdXNoIHRoZSBsaW1p dHMgb2YgdGhlIHJwaS4KCkpvaGFuCg== 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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_HIGH,USER_AGENT_MUTT 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 3A29AC10F0E for ; Mon, 15 Apr 2019 08:00:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 05E8E206BA for ; Mon, 15 Apr 2019 08:00:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555315258; bh=J+698oxhqHBOnMF8C8VUDpclE65kXybGTV8+R+kQBK8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=dcZ9g4xP23qS8D32HRKW/FkvV+VIQDzSOeJMJ2ygelwW+ZQtc/YcdmNZ4XieTLuyb /FJDVWUNT4xT6ZJwWbl7KE1guNKs9W0i5Rg4kM7yyRyqlUIpNNtF8Y9wKXw1wlsGb1 vAfjdkxv7bZEf6srB6p6xRZx5CfaffslX7EDW+Yc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726046AbfDOIA5 (ORCPT ); Mon, 15 Apr 2019 04:00:57 -0400 Received: from mail-lj1-f196.google.com ([209.85.208.196]:43352 "EHLO mail-lj1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725796AbfDOIA5 (ORCPT ); Mon, 15 Apr 2019 04:00:57 -0400 Received: by mail-lj1-f196.google.com with SMTP id f18so14691560lja.10; Mon, 15 Apr 2019 01:00:55 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=NzcgzxUNtWnsraNIBShDZ6XRg3i0t/Su0UrJJ7SzQFo=; b=O4sRvx5Mb1ftEeCQycjjeA28RCfoUsoI8bccPwNoOiCw6COOHR4jNxSJZVXIUpcXeK /2U5D/pUh5bc8hk11N3lrNZX1YI1XAtvItZ5tOmGzWALKqBn2QlOe78EsHxLCVOa+kGm 5AwYSiUwf0oKeD5Tke4nJdLx40lmu1NYEEnrbFd0tuxvb4sbHIISxUoW4eEuy29MSyfd PV4ri1TN3wGsPoxF9SvUatV7lBPe7P0Isokf8G2DwT+SfnLLRrQrr4efx9gHmcvJs1mM oqkQ6dN18ENqFhBhJClH1ZZBGHHieGL7g+lpJn1pK3mbhoUQSU8UBX6zmpk7erCBU50K LbVw== X-Gm-Message-State: APjAAAVzrx8OX+lVz7htvKcIsCnsGyOSUQUurmKKkNsPogl7AD+T9eYg yazKXWOHgT9hwmBxYpejaTRnd/xu X-Google-Smtp-Source: APXvYqwY/Gb907x1ZzRilH+F3WXrDf8CCQSgoQdZaGZJkrMksVRFyzq/otEGqQL5aPrJ6TLfQh2UiQ== X-Received: by 2002:a2e:99d2:: with SMTP id l18mr37824891ljj.27.1555315254650; Mon, 15 Apr 2019 01:00:54 -0700 (PDT) Received: from xi.terra (c-74bee655.07-184-6d6c6d4.bbcust.telenor.se. [85.230.190.116]) by smtp.gmail.com with ESMTPSA id w8sm3404125lfn.95.2019.04.15.01.00.53 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 15 Apr 2019 01:00:53 -0700 (PDT) Received: from johan by xi.terra with local (Exim 4.91) (envelope-from ) id 1hFwXy-0007oB-Fh; Mon, 15 Apr 2019 10:00:58 +0200 Date: Mon, 15 Apr 2019 10:00:58 +0200 From: Johan Hovold To: "Ramachandran Srinivasan (BRT-SG)" Cc: Johan Hovold , Greg Kroah-Hartman , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v2] usb: serial: defer URB submission for ftdi_sio Message-ID: <20190415080058.GA29656@localhost> References: <1554724399-2972-1-git-send-email-srinivasan.r@brtchip.com> <1554806826-11543-1-git-send-email-srinivasan.r@brtchip.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline In-Reply-To: <1554806826-11543-1-git-send-email-srinivasan.r@brtchip.com> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Message-ID: <20190415080058.re5Cv7jVux95rbsEg-6VTvsRWbXI-ptSsA-lgepu-wY@z> On Tue, Apr 09, 2019 at 10:47:42AM +0000, Ramachandran Srinivasan (BRT-SG) wrote: > From: Srinivasan R > > Deferring the URB resubmission, this can help time share the available > DMA chanels of DWC_OTG host controller in RaspberryPi.This change can > fix the problem, failed to enumerate the USB device when all the 8 > instance of ftdi_sio serial driver is open by application. many bugs > had been rasied for RaspberryPi around this problem can be solved Thanks for resending with a commit message. Your patch is still white-space damaged (check your mail setup, and make sure you can send a patch to yourself and apply it with git am), but with the above description I think I can give some feedback already. First of all, if there's a problem here, it would need to be fixed in the host-controller driver of the rpi as we don't want to add workarounds for host-controller issues to every USB driver. I suggest you write up an even more detailed bug report describing the problem you're seeing and send it to the list. Meanwhile, you can try increasing the latency timer of the connected ftdi devices to reduce the amount of traffic they generate when they're otherwise idle (16 ms default, can be increased up to 255 ms I think). That may possibly allow you to push the limits of the rpi. Johan