On 2016-01-20 18:50, Stefan Agner wrote:
> Using flat regmap cache instead of RB-tree to avoid the following
> lockdep warning on driver load:
> [ 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 FSL DCU 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 DCU driver is reasonable condense, hence
> using the much faster flat regmap cache is anyway the better
> choice.
>
> Signed-off-by: Stefan Agner <stefan at agner.ch>
> Cc: Mark Brown <broonie at kernel.org>
> ---
> drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c | 20 ++++++++++++--------
> drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h | 6 ++++--
> 2 files changed, 16 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> index e01c813..971c520 100644
> --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> @@ -36,11 +36,11 @@ static bool fsl_dcu_drm_is_volatile_reg(struct
> device *dev, unsigned int reg)
> return false;
> }
>
> -static const struct regmap_config fsl_dcu_regmap_config = {
> +static 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,
> };
> @@ -260,12 +260,14 @@ static const struct fsl_dcu_soc_data
> fsl_dcu_ls1021a_data = {
> .name = "ls1021a",
> .total_layer = 16,
> .max_layer = 4,
> + .max_register = LS1021A_DCU_MAX_REGISTER,
> };
>
> static const struct fsl_dcu_soc_data fsl_dcu_vf610_data = {
> .name = "vf610",
> .total_layer = 64,
> .max_layer = 6,
> + .max_register = VF610_DCU_MAX_REGISTER,
> };
>
> static const struct of_device_id fsl_dcu_of_match[] = {
> @@ -331,6 +333,14 @@ static int fsl_dcu_drm_probe(struct platform_device
> *pdev)
> return ret;
> }
>
> + id = of_match_node(fsl_dcu_of_match, pdev->dev.of_node);
> + if (!id)
> + return -ENODEV;
> +
> + drm = drm_dev_alloc(driver, dev);
> + fsl_dev->soc = id->data;
> +
> + fsl_dcu_regmap_config.max_register = fsl_dev->soc->max_register;
> fsl_dev->regmap = devm_regmap_init_mmio(dev, base,
> &fsl_dcu_regmap_config);
> if (IS_ERR(fsl_dev->regmap)) {
> @@ -338,12 +348,6 @@ static int fsl_dcu_drm_probe(struct platform_device
> *pdev)
> return PTR_ERR(fsl_dev->regmap);
> }
>
> - id = of_match_node(fsl_dcu_of_match, pdev->dev.of_node);
> - if (!id)
> - return -ENODEV;
> - fsl_dev->soc = id->data;
> -
> - drm = drm_dev_alloc(driver, dev);
> if (!drm)
> return -ENOMEM;
The drm_dev_alloc call should be close to its error handling, and moving
is anyway not necessary...
Will fix that in v2
--
Stefan
>
> diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> index 2a724f3..7c296a0 100644
> --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.h
> @@ -114,8 +114,6 @@
> #define DCU_UPDATE_MODE_MODE BIT(31)
> #define DCU_UPDATE_MODE_READREG BIT(30)
>
> -#define DCU_DCFB_MAX 0x300
> -
> #define DCU_CTRLDESCLN(layer, reg) (0x200 + (reg - 1) * 4 + (layer) * 0x40)
>
> #define DCU_LAYER_HEIGHT(x) ((x) << 16)
> @@ -155,6 +153,9 @@
> #define DCU_LAYER_POST_SKIP(x) ((x) << 16)
> #define DCU_LAYER_PRE_SKIP(x) (x)
>
> +#define VF610_DCU_MAX_REGISTER 0x11fc
> +#define LS1021A_DCU_MAX_REGISTER 0x5fc
> +
> #define FSL_DCU_RGB565 4
> #define FSL_DCU_RGB888 5
> #define FSL_DCU_ARGB8888 6
> @@ -175,6 +176,7 @@ struct fsl_dcu_soc_data {
> unsigned int total_layer;
> /*max layer number DCU supported*/
> unsigned int max_layer;
> + unsigned int max_register;
> };
>
> struct fsl_dcu_drm_device {
