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5f8838e940
In the i2c-hid remove() function we currently try to power off,
depopulate our child device, and free our resources. That's OK, but...
* If the i2c-hid device is on a power rail that can't turn off (either
an always-on or a shared power rail) we won't try to put the device
in a low power state during remove(). This probably doesn't matter
for very many devices but it could be nice in some instances.
* If the i2c-hid device somehow manages to generate an interrupt after
we tried to power off it is conceivable that the interrupt could
arrive during or after the call to hid_destroy_device() but before
the call to free_irq(). That could cause a crash since our IRQ
handler isn't expecting it. One could imagine this happening in
the case where we couldn't turn off (see the previous bullet) or,
possibly, if the interrupt line could glitch shortly after the
device powered off.
Let's call the suspend code during remove to avoid these issues. That
will put the device into a low power state and also disable
interrupts.
Technically, one could consider this a "fix" of commit 4a200c3b9a
("HID: i2c-hid: introduce HID over i2c specification implementation").
However, since the above bullet points are more theoretical than
problems seen on real systems and since the remove() of an i2c-hid
touchscreen isn't terribly likely to be called in production, it's
probably not worth the bother of trying to backport it.
Reviewed-by: Benjamin Tissoires <bentiss@kernel.org>
Acked-by: Benjamin Tissoires <bentiss@kernel.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230727101636.v4.8.Ic3ecad4a825905f4e4ce2a772b17f3c9cb2d60a2@changeid
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
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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.