linux-toradex.git/drivers/leds, branch v5.16

leds: trigger: Disable CPU trigger on PREEMPT_RT

2021-10-13T18:07:57+00:00

The CPU trigger is invoked on ARM from CPU-idle. That trigger later
invokes led_trigger_event() which may invoke the callback of the actual driver.
That driver can acquire a spinlock_t which is okay on kernel without
PREEMPT_RT. On a PREEMPT_RT enabled kernel this lock is turned into a
sleeping lock and must not be acquired with disabled interrupts.

Disable the CPU trigger on PREEMPT_RT.

Signed-off-by: Sebastian Andrzej Siewior 
Link: https://lkml.kernel.org/r/20210924111501.m57cwwn7ahiyxxdd@linutronix.de
Signed-off-by: Pavel Machek

leds: trigger: use RCU to protect the led_cdevs list

2021-09-27T14:16:42+00:00

Even with the previous commit 27af8e2c90fb
("leds: trigger: fix potential deadlock with libata")
to this file, we still get lockdep unhappy, and Boqun
explained the report here:
https://lore.kernel.org/r/YNA+d1X4UkoQ7g8a@boqun-archlinux

Effectively, this means that the read_lock_irqsave() isn't
enough here because another CPU might be trying to do a
write lock, and thus block the readers.

This is all pretty messy, but it doesn't seem right that
the LEDs framework imposes some locking requirements on
users, in particular we'd have to make the spinlock in the
iwlwifi driver always disable IRQs, even if we don't need
that for any other reason, just to avoid this deadlock.

Since writes to the led_cdevs list are rare (and are done
by userspace), just switch the list to RCU. This costs a
synchronize_rcu() at removal time so we can ensure things
are correct, but that seems like a small price to pay for
getting lock-free iterations and no deadlocks (nor any
locking requirements imposed on users.)

Signed-off-by: Johannes Berg 
Signed-off-by: Pavel Machek

led-class-flash: fix -Wrestrict warning

2021-09-27T14:09:42+00:00

gcc-11 warns when building with W=1:

drivers/leds/led-class-flash.c: In function 'flash_fault_show':
drivers/leds/led-class-flash.c:210:16: error: 'sprintf' argument 3 overlaps destination object 'buf' [-Werror=restrict]
  210 |         return sprintf(buf, "%s\n", buf);
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~
drivers/leds/led-class-flash.c:187:54: note: destination object referenced by 'restrict'-qualified argument 1 was declared here
  187 |                 struct device_attribute *attr, char *buf)
      |                                                ~~~~~~^~~

There is no need for the sprintf() here when a strcat() does
the same thing without invoking undefined behavior.

Signed-off-by: Arnd Bergmann 
Signed-off-by: Pavel Machek

leds: pca955x: Switch to i2c probe_new

2021-08-20T09:00:08+00:00

The deprecated i2c probe functionality doesn't work with OF
compatible strings, as it only checks for the i2c device id. Switch
to the new way of probing and grab the match data to select the
chip type.

Signed-off-by: Eddie James 
Signed-off-by: Pavel Machek

leds: pca955x: Let the core process the fwnode

2021-08-20T09:00:08+00:00

Much of the fwnode processing in the PCA955x driver is now in the
LEDs core driver, so pass the fwnode in the init data when
registering the LED device. In order to preserve the existing naming
scheme, check for an empty name and set it to the LED number.

Signed-off-by: Eddie James 
Signed-off-by: Pavel Machek

leds: pca955x: Implement the default-state property

2021-08-20T09:00:07+00:00

In order to retain the LED state after a system reboot, check the
documented default-state device tree property during initialization.
Modify the behavior of the probe according to the property.

Signed-off-by: Eddie James 
Signed-off-by: Pavel Machek

leds: pca955x: Add brightness_get function

2021-08-20T09:00:07+00:00

Add a function to fetch the state of the hardware LED.

Signed-off-by: Eddie James 
Signed-off-by: Pavel Machek

leds: pca955x: Clean up code formatting

2021-08-20T09:00:06+00:00

Format the code. Add some variables to help shorten lines.

Signed-off-by: Eddie James 
Signed-off-by: Pavel Machek

leds: leds-core: Implement the retain-state-shutdown property

2021-08-20T09:00:06+00:00

Read the retain-state-shutdown device tree property to set the
existing LED_RETAIN_AT_SHUTDOWN flag. Then check the flag when
unregistering, and if set, don't set the brightness to OFF. This
is useful for systems that want to keep the HW state of the LED
across reboots.

Signed-off-by: Eddie James 
Signed-off-by: Pavel Machek

leds: trigger: remove reference to obsolete CONFIG_IDE_GD_ATA

2021-08-18T06:59:47+00:00

Commit b7fb14d3ac63 ("ide: remove the legacy ide driver") removes the
definition of the config IDE_GD_ATA.

So, remove the obsolete reference in ./drivers/leds/trigger/Kconfig.

Signed-off-by: Lukas Bulwahn 
Signed-off-by: Pavel Machek