Unverified Commit e2f1ada8 authored by Pratap Nirujogi's avatar Pratap Nirujogi Committed by Andi Shyti
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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
38fa29b0 ("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: d6263c46 ("i2c: amd-isp: Add ISP i2c-designware driver")
Co-developed-by: default avatarBin Du <bin.du@amd.com>
Signed-off-by: default avatarBin Du <bin.du@amd.com>
Signed-off-by: default avatarPratap Nirujogi <pratap.nirujogi@amd.com>
Cc: <stable@vger.kernel.org> # v6.16+
Acked-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: default avatarMario Limonciello (AMD) <superm1@kernel.org>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: default avatarAndi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260320201302.3490570-1-pratap.nirujogi@amd.com
parent 13101db7

drivers/i2c/busses/i2c-designware-amdisp.c

+5 −6
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 


#include <linux/module.h>

#include <linux/platform_device.h>

#include <linux/pm_domain.h>

#include <linux/pm_runtime.h>

#include <linux/soc/amd/isp4_misc.h>
@@ -76,22 +77,20 @@ static int amd_isp_dw_i2c_plat_probe(struct platform_device *pdev) 


	device_enable_async_suspend(&pdev->dev);



	pm_runtime_enable(&pdev->dev);

	pm_runtime_get_sync(&pdev->dev);



	dev_pm_genpd_resume(&pdev->dev);

	ret = i2c_dw_probe(isp_i2c_dev);

	if (ret) {

		dev_err_probe(&pdev->dev, ret, "i2c_dw_probe failed\n");

		goto error_release_rpm;

	}



	pm_runtime_put_sync(&pdev->dev);

	dev_pm_genpd_suspend(&pdev->dev);

	pm_runtime_set_suspended(&pdev->dev);

	pm_runtime_enable(&pdev->dev);



	return 0;



error_release_rpm:

	amd_isp_dw_i2c_plat_pm_cleanup(isp_i2c_dev);

	pm_runtime_put_sync(&pdev->dev);

	return ret;

}