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regmap: teach regmap to use raw spinlocks if requested in the config

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Some drivers might access regmap in a context where a raw spinlock is
held. An example is drivers/irqchip/irq-ls-extirq.c, which calls
regmap_update_bits() from struct irq_chip :: irq_set_type, which is a
method called by __irq_set_trigger() under the desc->lock raw spin lock.

Since desc->lock is a raw spin lock and the regmap internal lock for
mmio is a plain spinlock (which can become sleepable on RT), this is an
invalid locking scheme and we get a splat stating that this is a
"[ BUG: Invalid wait context ]".

It seems reasonable for regmap to have an option use a raw spinlock too,
so add that in the config such that drivers can request it.

Suggested-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20210825205041.927788-2-vladimir.oltean@nxp.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Vladimir Oltean 2021-08-25 23:50:40 +03:00 • committed by Mark Brown
parent 6efb943b86
commit 67021f25d9
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GPG key ID: 24D68B725D5487D0
3 changed files with 36 additions and 5 deletions
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2
include/linux/regmap.h
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@ -343,6 +343,7 @@ typedef void (*regmap_unlock)(void *);
* @ranges: Array of configuration entries for virtual address ranges.
* @num_ranges: Number of range configuration entries.
* @use_hwlock: Indicate if a hardware spinlock should be used.
* @use_raw_spinlock: Indicate if a raw spinlock should be used.
* @hwlock_id: Specify the hardware spinlock id.
* @hwlock_mode: The hardware spinlock mode, should be HWLOCK_IRQSTATE,
* HWLOCK_IRQ or 0.
@ -402,6 +403,7 @@ struct regmap_config {
unsigned int num_ranges;
bool use_hwlock;
bool use_raw_spinlock;
unsigned int hwlock_id;
unsigned int hwlock_mode;