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drm/fsl-dcu: use flat regmap cache

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Using flat regmap cache instead of RB-tree to avoid the following
lockdep warning on driver load:
WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:2755 lockdep_trace_alloc+0x15c/0x160()
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 FSL DCU driver uses MMIO, the regmap bus of type
regmap_mmio is being used which has fast_io set to true.

Use flat regmap cache and specify max register to be large
enouth to cover all registers available in LS1021a and Vybrids
register space.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Cc: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
This commit is contained in:
Stefan Agner 2016-06-03 14:21:34 -07:00
parent af8c34ce6a
commit ce492b3b8f
1 changed files with 2 additions and 1 deletions
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3
drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
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@ -42,9 +42,10 @@ static const struct regmap_config fsl_dcu_regmap_config = {
.reg_bits = 32,
.reg_stride = 4,
.val_bits = 32,
.cache_type = REGCACHE_RBTREE,
.cache_type = REGCACHE_FLAT,
.volatile_reg = fsl_dcu_drm_is_volatile_reg,
.max_register = 0x11fc,
};
static int fsl_dcu_drm_irq_init(struct drm_device *dev)