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    Subject[PATCH 4.6 094/203] drm/fsl-dcu: use flat regmap cache
    Date
    4.6-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Stefan Agner <stefan@agner.ch>

    commit ce492b3b8f99cf9d2f807ec22d8805c996a09503 upstream.

    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>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
    +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
    @@ -40,9 +40,10 @@ static const struct regmap_config fsl_dc
    .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)

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