Using REGCACHE_RBTREE for MMIO regmap is not valid as spinlock's will be
used during cache allocation.
This fixes the following bug:
BUG: sleeping function called from invalid context at mm/slab.h:388
in_atomic(): 1, irqs_disabled(): 128, pid: 192, name: udevd
[...]
Signed-off-by: Alexander Stein <[email protected]>
---
Please refer also to the discussion at
https://lists.freedesktop.org/archives/dri-devel/2016-January/098696.html
drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
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 e8d9337..ea65140 100644
--- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
+++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
@@ -40,7 +40,7 @@ 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,
};
--
2.7.3
Hi Alexander,
On 2016-03-24 06:33, Alexander Stein wrote:
> Using REGCACHE_RBTREE for MMIO regmap is not valid as spinlock's will be
> used during cache allocation.
>
> This fixes the following bug:
> BUG: sleeping function called from invalid context at mm/slab.h:388
> in_atomic(): 1, irqs_disabled(): 128, pid: 192, name: udevd
> [...]
>
> Signed-off-by: Alexander Stein <[email protected]>
> ---
> Please refer also to the discussion at
> https://lists.freedesktop.org/archives/dri-devel/2016-January/098696.html
>
> drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> 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 e8d9337..ea65140 100644
> --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> @@ -40,7 +40,7 @@ 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,
To use flat regcache you also need to set the max_register.
I already have such a patch, see:
https://lists.freedesktop.org/archives/dri-devel/2016-January/099121.html
However, the current suspend/resume implementation (which uses the
regcache) is anyway flawed. I currently prepare a patchset to remove the
regmap cache entirely and use Thierry's new generic suspend/resume
functions.
--
Stefan
>
> .volatile_reg = fsl_dcu_drm_is_volatile_reg,
> };
On Friday 25 March 2016 09:24:28, Stefan Agner wrote:
> Hi Alexander,
>
> On 2016-03-24 06:33, Alexander Stein wrote:
> > Using REGCACHE_RBTREE for MMIO regmap is not valid as spinlock's will be
> > used during cache allocation.
> >
> > This fixes the following bug:
> > BUG: sleeping function called from invalid context at mm/slab.h:388
> > in_atomic(): 1, irqs_disabled(): 128, pid: 192, name: udevd
> > [...]
> >
> > Signed-off-by: Alexander Stein <[email protected]>
> > ---
> > Please refer also to the discussion at
> > https://lists.freedesktop.org/archives/dri-devel/2016-January/098696.html
> >
> > drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > 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 e8d9337..ea65140 100644
> > --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_drv.c
> > @@ -40,7 +40,7 @@ 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,
>
> To use flat regcache you also need to set the max_register.
Ah, thanks for that hint, I was not aware of that. I wondered why my kernel
crashed using flat cache. Seems cache allocation is too small when
max_register=0.
Just sent a patch enforcing setting max_register.
> I already have such a patch, see:
> https://lists.freedesktop.org/archives/dri-devel/2016-January/099121.html
Thanks, meanwhile this will do for me. I think.
> However, the current suspend/resume implementation (which uses the
> regcache) is anyway flawed. I currently prepare a patchset to remove the
> regmap cache entirely and use Thierry's new generic suspend/resume
> functions.
Feel free to cc me.
Best regards,
Alexander