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[ Upstream commit 2fe2b969d911a09abcd6a47401a3c66c38a310e6 ] Replaced pm_runtime_put() with pm_runtime_put_sync_suspend() to ensure the runtime suspend is invoked immediately when unregistering a slave. This prevents a race condition where suspend was skipped when unregistering and registering slave in quick succession. For example, consider the rapid sequence of `delete_device -> new_device -> delete_device -> new_device`. In this sequence, it is observed that the dw_i2c_plat_runtime_suspend() might not be invoked after `delete_device` operation. This is because after `delete_device` operation, when the pm_runtime_put() is about to trigger suspend, the following `new_device` operation might race and cancel the suspend. If that happens, during the `new_device` operation, dw_i2c_plat_runtime_resume() is skipped (since there was no suspend), which means `i_dev->init()`, i.e. i2c_dw_init_slave(), is skipped. Since i2c_dw_init_slave() is skipped, i2c_dw_configure_fifo_slave() is skipped too, which leaves `DW_IC_INTR_MASK` unconfigured. If we inspect the interrupt mask register using devmem, it will show as zero. Example shell script to reproduce the issue: ``` #!/bin/sh SLAVE_LADDR=0x1010 SLAVE_BUS=13 NEW_DEVICE=/sys/bus/i2c/devices/i2c-$SLAVE_BUS/new_device DELETE_DEVICE=/sys/bus/i2c/devices/i2c-$SLAVE_BUS/delete_device # Create initial device echo slave-24c02 $SLAVE_LADDR > $NEW_DEVICE sleep 2 # Rapid sequence of # delete_device -> new_device -> delete_device -> new_device echo $SLAVE_LADDR > $DELETE_DEVICE echo slave-24c02 $SLAVE_LADDR > $NEW_DEVICE echo $SLAVE_LADDR > $DELETE_DEVICE echo slave-24c02 $SLAVE_LADDR > $NEW_DEVICE # Using devmem to inspect IC_INTR_MASK will show as zero ``` Signed-off-by: Tan En De <ende.tan@starfivetech.com> Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com> Link: https://lore.kernel.org/r/20250412023303.378600-1-ende.tan@starfivetech.com Signed-off-by: Andi Shyti <andi.shyti@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.