On Tue, Jun 09, 2020 at 04:35:17PM +0200, Krzysztof Kozlowski wrote:
From: Stefan Agner stefan@agner.ch
commit ad06fdeeef1cbadf86ebbe510e8079abada8b44e upstream.
Use flat regmap cache to avoid lockdep warning at probe:
[ 0.697285] WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:2755 lockdep_trace_alloc+0x15c/0x160() [ 0.697449] DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags))
The RB-tree regmap cache needs to allocate new space on first writes. However, allocations in an atomic context (e.g. when a spinlock is held) are not allowed. The function regmap_write calls map->lock, which acquires a spinlock in the fast_io case. Since the pwm-fsl-ftm driver uses MMIO, the regmap bus of type regmap_mmio is being used which has fast_io set to true.
The MMIO space of the pwm-fsl-ftm driver is reasonable condense, hence using the much faster flat regmap cache is anyway the better choice.
Signed-off-by: Stefan Agner stefan@agner.ch Cc: Mark Brown broonie@kernel.org Signed-off-by: Thierry Reding thierry.reding@gmail.com Signed-off-by: Krzysztof Kozlowski krzk@kernel.org
Fixes lockdep warning. Apply to v4.4 and newer.
drivers/pwm/pwm-fsl-ftm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/pwm/pwm-fsl-ftm.c b/drivers/pwm/pwm-fsl-ftm.c index 7225ac6b3df5..fad968eb75f6 100644 --- a/drivers/pwm/pwm-fsl-ftm.c +++ b/drivers/pwm/pwm-fsl-ftm.c @@ -392,7 +392,7 @@ static const struct regmap_config fsl_pwm_regmap_config = { .max_register = FTM_PWMLOAD, .volatile_reg = fsl_pwm_volatile_reg,
- .cache_type = REGCACHE_RBTREE,
- .cache_type = REGCACHE_FLAT,
}; static int fsl_pwm_probe(struct platform_device *pdev) -- 2.17.1
Now queued up, thanks.
greg k-h