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Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=SATLEXMB03.amd.com; pr=C Received: from SATLEXMB03.amd.com (165.204.84.17) by MWH0EPF000971E6.mail.protection.outlook.com (10.167.243.74) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.7159.9 via Frontend Transport; Fri, 5 Jan 2024 12:53:51 +0000 Received: from SATLEXMB04.amd.com (10.181.40.145) by SATLEXMB03.amd.com (10.181.40.144) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.34; Fri, 5 Jan 2024 06:53:50 -0600 Received: from xhdvaralaxm41.xilinx.com (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server id 15.1.2507.34 via Frontend Transport; Fri, 5 Jan 2024 06:53:48 -0600 From: Sai Pavan Boddu To: , , CC: Michal Simek , Andi Shyti , Lars-Peter Clausen , Wolfram Sang Subject: [PATCH] i2c: cadence: Avoid fifo clear after start Date: Fri, 5 Jan 2024 18:22:58 +0530 Message-ID: <20240105125258.2470397-1-sai.pavan.boddu@amd.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-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MWH0EPF000971E6:EE_|IA1PR12MB6115:EE_ X-MS-Office365-Filtering-Correlation-Id: 32fae97b-ddbc-46b7-4452-08dc0ded5e3f X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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SFS:(13230031)(4636009)(396003)(39860400002)(346002)(376002)(136003)(230922051799003)(82310400011)(451199024)(64100799003)(1800799012)(186009)(40470700004)(36840700001)(46966006)(40460700003)(40480700001)(2616005)(478600001)(1076003)(336012)(426003)(6666004)(26005)(103116003)(86362001)(36860700001)(36756003)(82740400003)(356005)(81166007)(2906002)(41300700001)(4744005)(47076005)(70586007)(8676002)(5660300002)(110136005)(316002)(70206006)(54906003)(4326008)(8936002)(2101003)(36900700001); DIR:OUT; SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Jan 2024 12:53:51.7507 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 32fae97b-ddbc-46b7-4452-08dc0ded5e3f X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d; Ip=[165.204.84.17]; Helo=[SATLEXMB03.amd.com] X-MS-Exchange-CrossTenant-AuthSource: MWH0EPF000971E6.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR12MB6115 Driver unintentionally programs ctrl reg to clear fifo which is happening after start of transaction, this was not the case previously as it was read-modified-write. This issue breaks i2c reads on QEMU as i2c-read is done before guest starts programming ctrl register. Fixes: ff0cf7bca6309 ("i2c: cadence: Remove unnecessary register reads") Signed-off-by: Sai Pavan Boddu Acked-by: Michal Simek --- drivers/i2c/busses/i2c-cadence.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c index de3f58b60dce..6f7d753a8197 100644 --- a/drivers/i2c/busses/i2c-cadence.c +++ b/drivers/i2c/busses/i2c-cadence.c @@ -633,6 +633,7 @@ static void cdns_i2c_mrecv(struct cdns_i2c *id) if (hold_clear) { ctrl_reg &= ~CDNS_I2C_CR_HOLD; + ctrl_reg &= ~CDNS_I2C_CR_CLR_FIFO; /* * In case of Xilinx Zynq SOC, clear the HOLD bit before transfer size * register reaches '0'. This is an IP bug which causes transfer size