Re: [PATCH 0/5] gpiolib: Handle immutable irq_chip structures

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On 2022-02-24 16:40, Thierry Reding wrote:
On Wed, Feb 23, 2022 at 03:44:00PM +0000, Marc Zyngier wrote:
I recently realised that the gpiolib play ugly tricks on the
unsuspecting irq_chip structures by patching the callbacks.

Not only this breaks when an irq_chip structure is made const (which
really should be the default case), but it also forces this structure
to be copied at nauseam for each instance of the GPIO block, which is
a waste of memory.

My current approach is to add a new irq_chip flag (IRQCHIP_IMMUTABLE)
which does what it says on the tin: don't you dare writing there.
Gpiolib is further updated not to install its own callbacks, and it
becomes the responsibility of the driver to call into the gpiolib when
required. This is similar to what we do for other subsystems such as
PCI-MSI.

3 drivers are updated to this new model: M1, QC and Tegra, as I
actively use them (though Tegra is hosed at the moment), keeping a

Hosed in what way? Anything I can help with?

Tegra186 doesn't boot as host1x is been broken since -rc1.

I have been carrying this[1] patch which has been in -next for
some time, but still not merged AFAICS.

        M.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?h=irq/gpio-immutable&id=58d1d925f05485020306e5141336cfd2989843dc
--
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