diff mbox series

[3/3] gpio: TODO: track the removal of GPIOD_FLAGS_BIT_NONEXCLUSIVE

Message ID 20250331-gpio-todo-remove-nonexclusive-v1-3-25f72675f304@linaro.org
State New
Headers show
Series gpio: deprecate and track the removal of the GPIOD_FLAGS_BIT_NONEXCLUSIVE flag | expand

Commit Message

Bartosz Golaszewski March 31, 2025, 9 a.m. UTC 
From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

This flag should be replaced by a better mechanism that counts the users
and properly manages the resources. The pwrseq subsystem is a good
candidate. GPIOs themselves should remain a unique resource. Add a task
for tracking the removal of GPIOD_FLAGS_BIT_NONEXCLUSIVE.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 drivers/gpio/TODO | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
diff mbox series

Patch

diff --git a/drivers/gpio/TODO b/drivers/gpio/TODO
index b5f0a7a2e1bf1..5385071901993 100644
--- a/drivers/gpio/TODO
+++ b/drivers/gpio/TODO
@@ -186,3 +186,17 @@  their hardware offsets within the chip.
 
 Encourage users to switch to using them and eventually remove the existing
 global export/unexport attribues.
+
+-------------------------------------------------------------------------------
+
+Remove GPIOD_FLAGS_BIT_NONEXCLUSIVE
+
+This flag is an awful workaround that was created for some regulator
+corner-cases but got out of hand and is now used in at least 33 places
+treewide. Unlike what the intuition may tell users, it's not a reference
+counted mechanisms like what clocks or regulators use but just a raw access
+to the same GPIO descriptor from multiple places with no synchronization (other
+than what the underying driver offers). It doesn't even correctly support
+releasing the supposedly non-exclusive GPIOs. This whole thing should go and be
+replaced with a better solution - for exampe: using the relatively new power
+sequencing subsystem.