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b=1C16XJk/2EtlO76ygVW3TpcT8/5l3LzNYCtmK+8oTXTfdNoVbOAzKudWYNyXn+aDIO4ABPfN0+cTG0plKAxlRzWP7FoJM0XDaHbdR+Wje5Dq1mIhnrucAcqenO5wIN5L1swVXHLv+1XNHEPtltpjZTxrv4mFN/NbCBVzmL9Jf8E= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from SA0PR12MB4557.namprd12.prod.outlook.com (2603:10b6:806:9d::10) by MW6PR12MB8899.namprd12.prod.outlook.com (2603:10b6:303:248::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9700.11; Tue, 10 Mar 2026 01:29:08 +0000 Received: from SA0PR12MB4557.namprd12.prod.outlook.com ([fe80::885a:79b3:8288:287]) by SA0PR12MB4557.namprd12.prod.outlook.com ([fe80::885a:79b3:8288:287%5]) with mapi id 15.20.9700.010; Tue, 10 Mar 2026 01:29:08 +0000 Message-ID: <4527c72d-bc59-4f5d-af94-4b2f37d75a96@amd.com> Date: Mon, 9 Mar 2026 20:29:04 -0500 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1] i2c: designware: amdisp: Fix null pointer dereference in runtime resume To: Pratap Nirujogi , andi.shyti@kernel.org, mika.westerberg@linux.intel.com, andriy.shevchenko@linux.intel.com, jsd@semihalf.com Cc: rafael.j.wysocki@intel.com, mlimonci@amd.com, benjamin.chan@amd.com, bin.du@amd.com, king.li@amd.com, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260309220038.1420996-1-pratap.nirujogi@amd.com> Content-Language: en-US From: Mario Limonciello In-Reply-To: <20260309220038.1420996-1-pratap.nirujogi@amd.com> Content-Type: text/plain; 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The regmap may not be initialized yet when > runtime PM tries to resume the device early in the probe sequence, > leading to a NULL pointer dereference. Skip the i2c_dw_init() call > if regmap is not yet created. > > This race condition occurs when runtime PM resume is triggered before > i2c_dw_probe() completes the regmap initialization and was observed in > kernel v7.0 where the order of device enumeration has changed because > of the changes in registering the device sources in the device hierarchy. > > Co-developed-by: Bin Du > Fixes: 02c057ddefef ("ACPI: video: Convert the driver to a platform one") Is this the right commit that introduced the race? Did it change the timing? Or was the race always there and we just got lucky until that commit went in? > Signed-off-by: Pratap Nirujogi > --- > drivers/i2c/busses/i2c-designware-amdisp.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/i2c/busses/i2c-designware-amdisp.c b/drivers/i2c/busses/i2c-designware-amdisp.c > index c48728ad9f6f2..cd7ee55fbe1ee 100644 > --- a/drivers/i2c/busses/i2c-designware-amdisp.c > +++ b/drivers/i2c/busses/i2c-designware-amdisp.c > @@ -153,7 +153,10 @@ static int amd_isp_dw_i2c_plat_runtime_resume(struct device *dev) > return -ENODEV; > > i2c_dw_prepare_clk(i_dev, true); > - i2c_dw_init(i_dev); > + > + /* Skip i2c_dw_init if regmap not yet created by i2c_dw_probe */ > + if (i_dev->map) > + i2c_dw_init(i_dev); > > return 0; > }