[PATCH 6.19 255/342] i2c: designware: amdisp: Fix resume-probe race condition issue

Greg Kroah-Hartman
2026-03-31T16:42:16Z

From: Pratap Nirujogi <pratap.nirujogi@amd.com>

commit e2f1ada8e089dd5a331bcd8b88125ae2af8d188f upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/i2c/busses/i2c-designware-amdisp.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)

--- a/drivers/i2c/busses/i2c-designware-amdisp.c
+++ b/drivers/i2c/busses/i2c-designware-amdisp.c
@@ -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>

@@ -82,22 +83,20 @@ static int amd_isp_dw_i2c_plat_probe(str
if (isp_i2c_dev->shared_with_punit)
pm_runtime_get_noresume(&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;
}