From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zeus03.de (zeus03.de [194.117.254.33]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1F41A270EA2 for ; Thu, 1 May 2025 07:58:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=194.117.254.33 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746086288; cv=none; b=J/cyM6Fm5yKgvWXJJxKmrILCYcmOIlgECAzbCOO/4NCeD1amC3QxnAUQaQ93uU2G+2OaE8pp9ywQPLm35ElxnP0LCH1kS5zGK19qNgoCRfDAks6d3+n3LC3rfSgjgUTF4PYGnbZiQGA0Uk7LHwjCR6JpfmnmhDhoIJqLsxzugK0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746086288; c=relaxed/simple; bh=AMet2O0U655+gsWsG5t7/qer8SmvqpDgG/WhSKtrgOE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=fX4YHe262BFM3vdSN/HN2+4X6fgiP2nveoB8KAwzm/M0SgA4GQjqOgNB5/MLznCLrmH8jsY9zQvaz5agyNllAHPqJ0xG7XSn9oDakbA9ya/EuVaFaDcWkfXa6qD9j4l6+MCI5rszq5vaku+UgZICu4tV3ffxHeE9tikf52SafaM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sang-engineering.com; spf=pass smtp.mailfrom=sang-engineering.com; dkim=pass (2048-bit key) header.d=sang-engineering.com header.i=@sang-engineering.com header.b=Fsn+8PTh; arc=none smtp.client-ip=194.117.254.33 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sang-engineering.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sang-engineering.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=sang-engineering.com header.i=@sang-engineering.com header.b="Fsn+8PTh" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= sang-engineering.com; h=date:from:to:cc:subject:message-id :references:mime-version:content-type:in-reply-to; s=k1; bh=AMet 2O0U655+gsWsG5t7/qer8SmvqpDgG/WhSKtrgOE=; b=Fsn+8PThY/f44GssvN/h HPEihDGbELHJVdk2DYOzo19/yCeN/9f7GAXiu4DzslQh/AryLc1tFsn3iG1+XtKS i637GpBWs8/DieBSydpXYrJYzdhJ4elwjVlNEnR/Y6xJ4y8XTlN/+siGVbfktZ2K 6CpbgPYjoLMuXXGY9AZiUVrw8+In62mfUwy1VtnUD7fi9NIwXNXc/KktVJXThvqk an6249XyZvqB7TgoxLsDfQhZFemeWMiaBlVKLQRSw346EYKps9AnRJt0hq5nTucJ FVwkdYJevoO1OQ4BrtbGbPbNXLprEuE6R9vIWaVWOoF8z5gKr3goisFm0QVDdnmT Ag== Received: (qmail 980056 invoked from network); 1 May 2025 09:58:04 +0200 Received: by mail.zeus03.de with UTF8SMTPSA (TLS_AES_256_GCM_SHA384 encrypted, authenticated); 1 May 2025 09:58:04 +0200 X-UD-Smtp-Session: l3s3148p1@uRO6ZA40Do4gAwDPXxyAAIlRla1HkD11 Date: Thu, 1 May 2025 09:58:04 +0200 From: Wolfram Sang To: "Lad, Prabhakar" Cc: Chris Brandt , Andi Shyti , Geert Uytterhoeven , Andy Shevchenko , linux-renesas-soc@vger.kernel.org, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, Biju Das , Fabrizio Castro , Lad Prabhakar Subject: Re: [PATCH v9 2/2] i2c: riic: Recover from arbitration loss Message-ID: Mail-Followup-To: Wolfram Sang , "Lad, Prabhakar" , Chris Brandt , Andi Shyti , Geert Uytterhoeven , Andy Shevchenko , linux-renesas-soc@vger.kernel.org, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, Biju Das , Fabrizio Castro , Lad Prabhakar References: <20250430194647.332553-1-prabhakar.mahadev-lad.rj@bp.renesas.com> <20250430194647.332553-3-prabhakar.mahadev-lad.rj@bp.renesas.com> Precedence: bulk X-Mailing-List: linux-i2c@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="ZZ0WXadQ9QuHKhxu" Content-Disposition: inline In-Reply-To: --ZZ0WXadQ9QuHKhxu Content-Type: text/plain; charset=us-ascii Content-Disposition: inline > Do you mean that upon detecting an arbitration loss, we simply clear > the arbitration bit and retry? Yes, after the bus is considered free again. > However, when observing the SDA line after recovery, it goes LOW again > during the transfer. I've attached a screenshot of this case: we > recovered from a bus hang, the I2C recovery algorithm brought the bus > to a STOP state, and then a START condition was issued. But after > initiating the transfer, we can see the SDA line being held LOW again. That looks weird. Why are there two SDA transitions around 30us? Why is SDA changed while SCL is high around 45us? Then, this small SCL spike around 55us... 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