From owner-freebsd-hackers@freebsd.org Mon Aug 20 14:16:29 2018 Return-Path: Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 9CDFC106F02A for ; Mon, 20 Aug 2018 14:16:29 +0000 (UTC) (envelope-from marklmi26-fbsd@yahoo.com) Received: from sonic316-8.consmr.mail.gq1.yahoo.com (sonic316-8.consmr.mail.gq1.yahoo.com [98.137.69.32]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 215408EB90 for ; Mon, 20 Aug 2018 14:16:28 +0000 (UTC) (envelope-from marklmi26-fbsd@yahoo.com) X-YMail-OSG: VGq812IVM1lkSSyCICS7JNpmc08qdmmUfRq9G_L.SPS2B9B.jtpgvnkryc5ddAp JvYr3TraqG1AP3Q8V0JxHlcltE1JQPQubTmqx5gREabq3vEiG_TKLWLvvS2cOpQkkkNAbvzXOxSg zIX4gzbJnCwauF5z8dFaDMm_BacpoQsFOrPb4VTeflr8tjgD3TrPGJf1_XHEUFu71t0d.V_HhSCv 9H7M55XBSyfoReBDvA2wTcAVNC.5xwnjOYxfcfp7m1iWAjv_nt63aAd.NoiVqRMxbxKDWZz.mmRW cVayd3nA4PQ7blrOU.3RBpydF8H_jYVCXPvSFtho_mGDc0TYCj6nuxf8kluYYvW_ZyKCI1vbE5D1 lWKAxvBUHIzf1n5phUAkVGNMMndCR7rcGXVeN8rex2YGZu7zjhZUU9uoN4Ox9uM3MfHNo9vYgMxP icNEqi4PDCDPnCMLY6DYMKMAR3AmLwwIiTUr.Fd0CbQCtMUxUCKiW1uOsYrTL7tt2QbndGTsR7Ku hQBX1LrcT5Do95TD_0LVG_RXxi4KQ2atypjUbidNGY_VUu15IVxPfFAGMfHkQ1xK4jYyoVLab_f9 5jWBPqyoScfQzPkGcq4dyuqpD.xgzgyZeOmNxTMJZVohZ3pDAMS0jgqafiNLtb4ONBBSRT9ABinp f3q03VQehflY3GLsvosamJ_0.n19KRF48CfTwVeQQmWymENjMB7E2kBLv9yai584Qn_YinvzQXmi k0.hIboCNSEqqptBzKQZc1Xcl6oa5mbiJMxHmaf8q27UXVFZHUwOIOC8S8HcCc8aGeVnz6YnpMFu gTGMFtbKF7D_kv.ZpzMjGzyDOjGbdqV21aqRVLuiwNCft78vmcdjeuCvnwdBDtsJiLcC4skzuulW tqJS7hQuH3nB4bVTDxXWkAb.Aa5EWbQqdUqOHqHdhrPIE5U.H.mC07CUpcQ5q6wWyZaYgQ2io7xK ssHgeN.HaEncVIHb_nXj5AT_CTOCdCZwp3qJdWOKGhkqbbzYkSFfYpSMjhFO.ILU3Dwf8esUOcjZ ZKGiKurJ8 Received: from sonic.gate.mail.ne1.yahoo.com by sonic316.consmr.mail.gq1.yahoo.com with HTTP; Mon, 20 Aug 2018 14:16:21 +0000 Received: from ip70-189-131-151.lv.lv.cox.net (EHLO [192.168.0.105]) ([70.189.131.151]) by smtp410.mail.gq1.yahoo.com (Oath Hermes SMTP Server) with ESMTPA ID d257edfd13b2bed4706d68af7d4e1a91; Mon, 20 Aug 2018 14:16:18 +0000 (UTC) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) Subject: Re: Need a clarification regarding I2C bus frequency in FreeBSD From: Mark Millard In-Reply-To: <1534771095.27158.46.camel@freebsd.org> Date: Mon, 20 Aug 2018 07:16:15 -0700 Cc: Ian Lepore , Rajesh Kumar , Toomas Soome via freebsd-hackers , freebsd-drivers@freebsd.org Content-Transfer-Encoding: quoted-printable Message-Id: <35F2C250-B4CB-4C53-BF8F-43C338022E34@yahoo.com> References: <1534523216.27158.17.camel@freebsd.org> <1534702861.27158.36.camel@freebsd.org> <1534771095.27158.46.camel@freebsd.org> To: Daniel Braniss X-Mailer: Apple Mail (2.3445.9.1) X-Mailman-Approved-At: Mon, 20 Aug 2018 15:03:29 +0000 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.27 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 20 Aug 2018 14:16:29 -0000 On 2018-Aug-20, at 6:18 AM, Ian Lepore wrote: > On Mon, 2018-08-20 at 11:13 +0300, Daniel Braniss wrote: >>=20 >>>=20 >>> On 20 Aug 2018, at 09:49, Daniel Braniss = wrote: >>>=20 >>>> . . . >>>=20 >>> hi, >>> I have similar issues with the allwinner/twsi but I do have a Saleae = Logic and here is a nice picture: >> ah, maybe this is better: >> = https://cs.huji.ac.il/~danny/Screen%20Shot%202018-08-20%20at%2011.06.43.pn= g > . . . > This has nothing to do with the twsi driver, this is about the ig4 > driver (found in sys/dev/ichiic). >=20 > That screenshot seems to show a bus running at 100KHz like it should > (although the 62:38 duty cycle is a bit suspicious). Being a logic analyzer display, it my just be that the threshold was off from the optimal value. The waveform shape is not really visible. The logic analyzer output also shows a thick "rising" edge without the uparrow symbol. My guess would be that is a rising/falling/rising sequence that on the scale in use does not show space between edges. In other words: a glitch on the leading edge side of the intended pulse. This too might be tied to the threshold used vs . the actual signal properties: no way to tell from what is shown. =3D=3D=3D Mark Millard marklmi at yahoo.com ( dsl-only.net went away in early 2018-Mar)