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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E748EC04A95 for ; Wed, 28 Sep 2022 15:50:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233225AbiI1Pup convert rfc822-to-8bit (ORCPT ); Wed, 28 Sep 2022 11:50:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36210 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232096AbiI1Puo (ORCPT ); Wed, 28 Sep 2022 11:50:44 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.86.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AA78A82627 for ; Wed, 28 Sep 2022 08:50:42 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-265-epL-6jk9N7WF2cxyMBC7Tg-1; Wed, 28 Sep 2022 16:50:40 +0100 X-MC-Unique: epL-6jk9N7WF2cxyMBC7Tg-1 Received: from AcuMS.Aculab.com (10.202.163.4) by AcuMS.aculab.com (10.202.163.4) with Microsoft SMTP Server (TLS) id 15.0.1497.38; Wed, 28 Sep 2022 16:50:36 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.040; Wed, 28 Sep 2022 16:50:36 +0100 From: David Laight To: 'Michael Zaidman' , "jikos@kernel.org" CC: "linux-kernel@vger.kernel.org" , "linux-input@vger.kernel.org" , "Guillaume Champagne" Subject: RE: [PATCH v2 2/7] HID: ft260: improve i2c write performance Thread-Topic: [PATCH v2 2/7] HID: ft260: improve i2c write performance Thread-Index: AQHY00mUw0Kqs3OAvUmX6aS0EWBX1630/Gwg Date: Wed, 28 Sep 2022 15:50:36 +0000 Message-ID: References: <20220928144854.5580-1-michael.zaidman@gmail.com> <20220928144854.5580-3-michael.zaidman@gmail.com> In-Reply-To: <20220928144854.5580-3-michael.zaidman@gmail.com> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org From: Michael Zaidman > Sent: 28 September 2022 15:49 > > The patch improves i2c writing performance by about 30 percent by revising > the sleep time in the ft260_hid_output_report_check_status() in the > following ways: Spinning in kernel for several milliseconds isn't friendly at all. David > > 1. Reduce the sleep time and start to poll earlier: > > Before: > $ sudo ./i2cperf -f 2 -o 2 -s 32 -r 0-0xff 13 0x51 -S > > Fill block with increment via i2ctransfer by chunks > ------------------------------------------------------------------- > data rate(bps) efficiency(%) data size(B) total IOs IO size(B) > ------------------------------------------------------------------- > 40510 80 256 8 32 > > After: > $ sudo ./i2cperf -f 2 -o 2 -s 32 -r 0-0xff 13 0x51 -S > > Fill block with increment via i2ctransfer by chunks > ------------------------------------------------------------------- > data rate(bps) efficiency(%) data size(B) total IOs IO size(B) > ------------------------------------------------------------------- > 52584 80 256 8 32 > > 2. Do not sleep when the calculated sleep time is below 2 ms: > > Before: > $ sudo ./i2cperf -f 2 -o 2 -s 16 -r 0-0xff 13 0x51 -S > > Fill block with increment via i2ctransfer by chunks > ------------------------------------------------------------------- > data rate(bps) efficiency(%) data size(B) total IOs IO size(B) > ------------------------------------------------------------------- > 26707 73 256 16 16 > > After: > $ sudo ./i2cperf -f 2 -o 2 -s 16 -r 0-0xff 13 0x51 -S > > Fill block with increment via i2ctransfer by chunks > ------------------------------------------------------------------- > data rate(bps) efficiency(%) data size(B) total IOs IO size(B) > ------------------------------------------------------------------- > 37034 73 256 16 16 > > Link to the i2cperf - https://github.com/MichaelZaidman/i2cperf > > Signed-off-by: Michael Zaidman > Tested-by: Guillaume Champagne > --- > drivers/hid/hid-ft260.c | 14 +++++++++----- > 1 file changed, 9 insertions(+), 5 deletions(-) > > diff --git a/drivers/hid/hid-ft260.c b/drivers/hid/hid-ft260.c > index a35201d68b15..44106cadd746 100644 > --- a/drivers/hid/hid-ft260.c > +++ b/drivers/hid/hid-ft260.c > @@ -345,7 +345,7 @@ static int ft260_hid_output_report(struct hid_device *hdev, u8 *data, > static int ft260_hid_output_report_check_status(struct ft260_device *dev, > u8 *data, int len) > { > - int ret, usec, try = 3; > + int ret, usec, try = 100; > struct hid_device *hdev = dev->hdev; > > ret = ft260_hid_output_report(hdev, data, len); > @@ -356,10 +356,14 @@ static int ft260_hid_output_report_check_status(struct ft260_device *dev, > return ret; > } > > - /* transfer time = 1 / clock(KHz) * 10 bits * bytes */ > - usec = 10000 / dev->clock * len; > - usleep_range(usec, usec + 100); > - ft260_dbg("wait %d usec, len %d\n", usec, len); > + /* transfer time = 1 / clock(KHz) * 9 bits * bytes */ > + usec = len * 9000 / dev->clock; > + if (usec > 2000) { > + usec -= 1500; > + usleep_range(usec, usec + 100); > + ft260_dbg("wait %d usec, len %d\n", usec, len); > + } > + > do { > ret = ft260_xfer_status(dev); > if (ret != -EAGAIN) > -- > 2.34.1 - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)