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i2c: designware: amdisp: Fix resume-probe race condition issue

Identified resume-probe race condition in kernel v7.0 with the commit
38fa29b01a6a ("i2c: designware: Combine the init functions"),but this
issue existed from the beginning though not detected.

The amdisp i2c device requires ISP to be in power-on state for probe
to succeed. To meet this requirement, this device is added to genpd
to control ISP power using runtime PM. The pm_runtime_get_sync() called
before i2c_dw_probe() triggers PM resume, which powers on ISP and also
invokes the amdisp i2c runtime resume before the probe completes resulting
in this race condition and a NULL dereferencing issue in v7.0

Fix this race condition by using the genpd APIs directly during probe:
- Call dev_pm_genpd_resume() to Power ON ISP before probe
- Call dev_pm_genpd_suspend() to Power OFF ISP after probe
- Set the device to suspended state with pm_runtime_set_suspended()
- Enable runtime PM only after the device is fully initialized

Fixes: d6263c468a761 ("i2c: amd-isp: Add ISP i2c-designware driver")
Co-developed-by: Bin Du <bin.du@amd.com>
Signed-off-by: Bin Du <bin.du@amd.com>
Signed-off-by: Pratap Nirujogi <pratap.nirujogi@amd.com>
Cc: <stable@vger.kernel.org> # v6.16+
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260320201302.3490570-1-pratap.nirujogi@amd.com

authored by

Pratap Nirujogi and committed by
Andi Shyti e2f1ada8 13101db7

+5 -6
+5 -6
drivers/i2c/busses/i2c-designware-amdisp.c
··· 7 7 8 8 #include <linux/module.h> 9 9 #include <linux/platform_device.h> 10 + #include <linux/pm_domain.h> 10 11 #include <linux/pm_runtime.h> 11 12 #include <linux/soc/amd/isp4_misc.h> 12 13 ··· 77 76 78 77 device_enable_async_suspend(&pdev->dev); 79 78 80 - pm_runtime_enable(&pdev->dev); 81 - pm_runtime_get_sync(&pdev->dev); 82 - 79 + dev_pm_genpd_resume(&pdev->dev); 83 80 ret = i2c_dw_probe(isp_i2c_dev); 84 81 if (ret) { 85 82 dev_err_probe(&pdev->dev, ret, "i2c_dw_probe failed\n"); 86 83 goto error_release_rpm; 87 84 } 88 - 89 - pm_runtime_put_sync(&pdev->dev); 85 + dev_pm_genpd_suspend(&pdev->dev); 86 + pm_runtime_set_suspended(&pdev->dev); 87 + pm_runtime_enable(&pdev->dev); 90 88 91 89 return 0; 92 90 93 91 error_release_rpm: 94 92 amd_isp_dw_i2c_plat_pm_cleanup(isp_i2c_dev); 95 - pm_runtime_put_sync(&pdev->dev); 96 93 return ret; 97 94 } 98 95