From patchwork Thu Dec 7 16:50:26 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Elad Nachman X-Patchwork-Id: 752147 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=marvell.com header.i=@marvell.com header.b="T3kR0wVa" Received: from mx0b-0016f401.pphosted.com (mx0a-0016f401.pphosted.com [67.231.148.174]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C2F4B10D1; Thu, 7 Dec 2023 08:50:37 -0800 (PST) Received: from pps.filterd (m0045849.ppops.net [127.0.0.1]) by mx0a-0016f401.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 3B7GaW9K017013; Thu, 7 Dec 2023 08:50:34 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=marvell.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding : content-type; s=pfpt0220; bh=3eom/CEVJfqf9PXnBTndbKR1eTIsvJGA5a21Gg4EphA=; b=T3kR0wVaignp+14pi0xtWiqdMLSkzs3k/deEJ79t2DS3Q0HU2q+GlIKIa9xDtep7yrD+ 3BvKj3AcDjI+zy9zG9CR2ap7EBz0+tf5mX5nrBxKTi3vtnFS5G3lZl8o8mlHeY5UGTkS eTSL/HyNSrJ/bw8RYi326UrU526uB+oGYShIqMWQ6q94OC/1LzskWlJQ5EmNNYrDykPZ KULi4dRYJejc6fpBh7dhXYk2VktQGWV41vdPaZb+FO0umTi93kwnqBFsMpjpdq3QEPMB /610lYhlcdQp2zAJns0kmT6Akzx2hUmBp4mDCAHMjyiHhT7RPIJHO79MnksfRYNWQ9VV kw== Received: from dc5-exch01.marvell.com ([199.233.59.181]) by mx0a-0016f401.pphosted.com (PPS) with ESMTPS id 3uu8qea436-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT); Thu, 07 Dec 2023 08:50:33 -0800 Received: from DC5-EXCH02.marvell.com (10.69.176.39) by DC5-EXCH01.marvell.com (10.69.176.38) with Microsoft SMTP Server (TLS) id 15.0.1497.48; Thu, 7 Dec 2023 08:50:32 -0800 Received: from maili.marvell.com (10.69.176.80) by DC5-EXCH02.marvell.com (10.69.176.39) with Microsoft SMTP Server id 15.0.1497.48 via Frontend Transport; Thu, 7 Dec 2023 08:50:31 -0800 Received: from dc3lp-swdev041.marvell.com (dc3lp-swdev041.marvell.com [10.6.60.191]) by maili.marvell.com (Postfix) with ESMTP id 696623F709B; Thu, 7 Dec 2023 08:50:30 -0800 (PST) From: Elad Nachman To: , , , CC: , Subject: [PATCH v2 0/1] i2c: busses: i2c-mv64xxx: fix arb-loss i2c lock Date: Thu, 7 Dec 2023 18:50:26 +0200 Message-ID: <20231207165027.2628302-1-enachman@marvell.com> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-i2c@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Proofpoint-GUID: qLmyGKCtlt3WJ1-qoH0ibpbqy_rVOdZw X-Proofpoint-ORIG-GUID: qLmyGKCtlt3WJ1-qoH0ibpbqy_rVOdZw X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.997,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-12-07_14,2023-12-07_01,2023-05-22_02 From: Elad Nachman Some i2c slaves, mainly SFPs, might cause the bus to lose arbitration while slave is in the middle of responding. This means that the i2c slave has not finished the transmission, but the master has already finished toggling the clock, probably due to the slave missing some of the master's clocks. This was seen with Ubiquity SFP module. This is typically caused by slaves which do not adhere completely to the i2c standard. The solution is to change the I2C mode from mpps to gpios, and toggle the i2c_scl gpio to emulate bus clock toggling, so slave will finish its transmission, driven by the manual clock toggling, and will release the i2c bus. v2: 1) Explain more about cause of issue in commit message 2) Change variable name to something clearer 3) Leave space between comments 4) Remove redundant blank line 5) Add error message if pinctrl get failed 6) Move gpio request to probe function 7) Fix commenting style 8) Explain in comments why 10 togglings are required 9) Move from mdelay to udelay, reducing delay time 10) Explain in comments what is the value written to the reset register. 11) Explain why fallthrough is required (generate stop condition) 12) Explain why in case of missing i2c arbitration loss details, driver probe will not fail, in order to be backward compatible with older dts files Elad Nachman (1): i2c: busses: i2c-mv64xxx: fix arb-loss i2c lock drivers/i2c/busses/i2c-mv64xxx.c | 113 +++++++++++++++++++++++++++++++ 1 file changed, 113 insertions(+)