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authorMarc Zyngier <maz@kernel.org>2022-04-19 15:18:45 +0100
committerMarc Zyngier <maz@kernel.org>2022-04-19 15:22:26 +0100
commitafefc3266272d40cdcd0fd713c7b42008fea19d5 (patch)
tree2891ef14e9051fd2f107efae4dbcdf74babc100a
parent6173e56f76c712aac9d45208ccec7a065382911f (diff)
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: Andy Shevchenko <andy.shevchenko@gmail.com> Reviewed-by: Bartosz Golaszewski <brgl@bgdev.pl> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20220419141846.598305-10-maz@kernel.org
-rw-r--r--drivers/gpio/TODO19
1 files changed, 19 insertions, 0 deletions
diff --git a/drivers/gpio/TODO b/drivers/gpio/TODO
index b8b1473a5b1e..f87ff3fa8a53 100644
--- a/drivers/gpio/TODO
+++ b/drivers/gpio/TODO
@@ -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!