Commit afefc326 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

gpio: Update TODO to mention immutable irq_chip structures 



5 drivers are converted, a few hundred to go. Definitely worth of
a TODO entry, in the hope that someone will notice it and do
a bulk update.

Reviewed-by: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: default avatarBartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220419141846.598305-10-maz@kernel.org
parent 6173e56f

drivers/gpio/TODO

+19 −0
Original line number Diff line number Diff line
@@ -178,3 +178,22 @@ discussed but the idea is to provide a low-level access point 
for debugging and hacking and to expose all lines without the

need of any exporting. Also provide ample ammunition to shoot

oneself in the foot, because this is debugfs after all.





Moving over to immutable irq_chip structures



Most of the gpio chips implementing interrupt support rely on gpiolib

intercepting some of the irq_chip callbacks, preventing the structures

from being made read-only and forcing duplication of structures that

should otherwise be unique.



The solution is to call into the gpiolib code when needed (resource

management, enable/disable or unmask/mask callbacks), and to let the

core code know about that by exposing a flag (IRQCHIP_IMMUTABLE) in

the irq_chip structure. The irq_chip structure can then be made unique

and const.



A small number of drivers have been converted (pl061, tegra186, msm,

amd, apple), and can be used as examples of how to proceed with this

conversion. Note that drivers using the generic irqchip framework

cannot be converted yet, but watch this space!