From patchwork Mon Dec 11 12:01:28 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Elad Nachman X-Patchwork-Id: 752805 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=marvell.com header.i=@marvell.com header.b="awCT9xfC" Received: from mx0b-0016f401.pphosted.com (mx0a-0016f401.pphosted.com [67.231.148.174]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 81080137; Mon, 11 Dec 2023 04:01:40 -0800 (PST) Received: from pps.filterd (m0045849.ppops.net [127.0.0.1]) by mx0a-0016f401.pphosted.com (8.17.1.24/8.17.1.24) with ESMTP id 3BB9IEYK009898; Mon, 11 Dec 2023 04:01:36 -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=h0QNwsIs xCVCFnb61YiC0y8uyBswFifMu55wtofMhKA=; b=awCT9xfCMKHJgzaWicpcLmAs jqpxb/mwQpK+R3grVz1y1fz19XU3JY9JzCLkzWVWWg3nU5VTUuTPEhAPjGHL8HwV gAi37qrDqv2ka9m2TSpRZ9yp/gsm8wYgJCQ0R9ns797zPHkx6kYybjLOe745Ebkd CGYNWxwBLFqeMsOWtVh185ka3CFgUDaL/20qrVngQbGdsqIzyDCyutopq1i9vCS8 Jt0s2VpWbkdSV0tSBjkIqZVvKf0qTaavWBwb6JY/PVam6BTY+Hp7qERcZzud1EDm v/nYAiYeM5KpqbqheIhZHhtJxVMYOX9kh4iY9jHoDmdaOqvJACDm82sbea9qpQ== Received: from dc5-exch01.marvell.com ([199.233.59.181]) by mx0a-0016f401.pphosted.com (PPS) with ESMTPS id 3uwyp4gfjk-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT); Mon, 11 Dec 2023 04:01:36 -0800 (PST) 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; Mon, 11 Dec 2023 04:01:35 -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; Mon, 11 Dec 2023 04:01:34 -0800 Received: from dc3lp-swdev041.marvell.com (dc3lp-swdev041.marvell.com [10.6.60.191]) by maili.marvell.com (Postfix) with ESMTP id 530E63F7045; Mon, 11 Dec 2023 04:01:33 -0800 (PST) From: Elad Nachman To: , , , CC: , Subject: [PATCH v3 0/1] i2c: busses: i2c-mv64xxx: fix arb-loss i2c lock Date: Mon, 11 Dec 2023 14:01:28 +0200 Message-ID: <20231211120129.3719469-1-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-ORIG-GUID: _89VZfFsXvVH5A_7vJDI7Kvq921FjJ-J X-Proofpoint-GUID: _89VZfFsXvVH5A_7vJDI7Kvq921FjJ-J 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=2023-12-09_02,2023-12-07_01,2023-05-22_02 From: Elad Nachman i2c: busses: i2c-mv64xxx: fix arb-loss i2c lock 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. v3: 1) Remove unused / un-initialized variable 2) Replace devm_pinctrl_get() with pinctrl_get() and pinctrl_put() pair in probe and device removal. 3) Replace atomic sleeps with usleep_range() 4) Rework comment to start with a capital letter 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 | 118 ++++++++++++++++++++++++++++++- 1 file changed, 117 insertions(+), 1 deletion(-)