From owner-freebsd-hackers@freebsd.org Mon Aug 20 16:00:23 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 6CE4110734D1 for ; Mon, 20 Aug 2018 16:00:23 +0000 (UTC) (envelope-from marklmi@yahoo.com) Received: from sonic315-13.consmr.mail.bf2.yahoo.com (sonic315-13.consmr.mail.bf2.yahoo.com [74.6.134.123]) (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 150E073D84 for ; Mon, 20 Aug 2018 16:00:22 +0000 (UTC) (envelope-from marklmi@yahoo.com) X-YMail-OSG: uwn8u18VM1leMvAyyZrxR2bwiVUsTeA6Otq1iyo30byDwzlYi_UyJSeTgxIV3NZ diRU85xcQeM.Ucnr6k9rRkvr9RE9UUd5PxZ21cZ8B08YsHogLVkjFZl404F1mgY2SIUJoBnuTXuo f5FrS7zpuIbBf_HyYOzLcAGix7eRuJHt6119Gh4C1w24_.Srg2oBRKcVl.4JJkNE2q0X7SWSvhGi G9rvZp6f4rxo_bE527YIOwgZHe6G0b7DBZAQH4OBhM09IufiaChH9oc8j4D1j8KwRKdnsq_Rf.QB p9vyMGX91lRZqbPZ1C5J1Kw7sulMHAhFTgv.7t_eFGQmOtpOY5VNlplvFD.PEa5tvc6kkYIwebQa o0tBSwlWunrc4aodrQIfBAd1WsSGVlBQ8h_OLKn._91GNwz1iGLnyOJlzpg1C03OQg.q3UEu9CCn ds7zMWQ.PKREWnhLcfu6wnt.Y_sF_TUZufRb4SVbipkfyvaWPxe4UN9iwUFm0yaqaC9fB1D0c36I QA3Yg1zWUwdhtJKqCvwKUlc9qV1NFNTc0s5RQccp66kzoIV9BYtdFPiTvz3ueBWngxxgkef_1sOy 9NpsiY_B4uxsxg7gKlD48z2RxmnAp2Trx9bKXFI68rPY.mrEptRhVx_3L474rjG5FloChoyMMLiL 49506nsWA7ySz_.R_IyRBHSbImMsoMV63KIK0SnYRUz0niPr_A0U4C4Hfn0k__NkyQAP2pF8ExuH SKd4XEvy561VP3dir0L0.QcVB44nlQFVnCkCX.cGGWEY4XMikOrRnP4bAUwAsbRpOW2GCQcpCHG7 mZqKUy5g5.KoZd5PHnHmcIyKuJMNJ1OpX1sZ8OuDv24eCdwEGb9nDwjbep5fVQlq4l2AxOxDE1FZ lCKz3NOA0wz0COlNjunTCBUqaz849szXY_3fKOO1JymTQeVwQxZ.Pebbn23cluXaEIRnxy1wvl00 jaAEluIiGEQCSCiAwcdXKrvOoRchGAABBNIuoZonXWWd_N3tyqNgJG1acwRXFNIWnjGoNhrK3wNc DF1.bW3U6YuJ1.w-- Received: from sonic.gate.mail.ne1.yahoo.com by sonic315.consmr.mail.bf2.yahoo.com with HTTP; Mon, 20 Aug 2018 16:00:22 +0000 Received: from ip70-189-131-151.lv.lv.cox.net (EHLO [192.168.0.105]) ([70.189.131.151]) by smtp422.mail.bf1.yahoo.com (Oath Hermes SMTP Server) with ESMTPA ID 218f368d65d3a390e5ff3d4a5d591849; Mon, 20 Aug 2018 16:00:19 +0000 (UTC) From: Mark Millard Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) Subject: Fwd: Need a clarification regarding I2C bus frequency in FreeBSD Message-Id: References: <35F2C250-B4CB-4C53-BF8F-43C338022E34@yahoo.com> To: Toomas Soome via freebsd-hackers , freebsd-drivers@freebsd.org Date: Mon, 20 Aug 2018 09:00:17 -0700 X-Mailer: Apple Mail (2.3445.9.1) 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 16:00:23 -0000 [Resend to (just the list) from the right account.] 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)