diff mbox series

Revert "ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach_device()"

Message ID 20190114132240.12125-1-m.szyprowski@samsung.com
State New
Headers show
Series Revert "ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach_device()" | expand

Commit Message

Marek Szyprowski Jan. 14, 2019, 1:22 p.m. UTC 
This reverts commit 1874619a7df4b14b23b14877e705ae15325773e3.

That patch broke IOMMU support for devices, which fails to probe for the
first time and use deferred probe approach. When non-NULL dma_ops is set
in arm_iommu_detach_device(), the given device later ignored by
arch_setup_dma_ops() and stays with non-IOMMU dma_ops.

Reported-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
Fixes: 1874619a7df4 "ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach_device()"
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

---
 arch/arm/mm/dma-mapping.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

-- 
2.17.1

Comments

Thierry Reding Jan. 14, 2019, 4:09 p.m. UTC | #1 
On Mon, Jan 14, 2019 at 02:22:40PM +0100, Marek Szyprowski wrote:
> This reverts commit 1874619a7df4b14b23b14877e705ae15325773e3.

> 

> That patch broke IOMMU support for devices, which fails to probe for the

> first time and use deferred probe approach. When non-NULL dma_ops is set

> in arm_iommu_detach_device(), the given device later ignored by

> arch_setup_dma_ops() and stays with non-IOMMU dma_ops.

> 

> Reported-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>

> Fixes: 1874619a7df4 "ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach_device()"

> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

> ---

>  arch/arm/mm/dma-mapping.c | 12 ++++++------

>  1 file changed, 6 insertions(+), 6 deletions(-)


Can you point out exactly what drivers break because of this change? We
need to find a solution that works for everyone. Reverting is only
marginally useful because somebody will just end up wanting to revert
the revert because a different driver is now broken.

Thierry
Robin Murphy Jan. 14, 2019, 4:38 p.m. UTC | #2 
On 14/01/2019 16:09, Thierry Reding wrote:
> On Mon, Jan 14, 2019 at 02:22:40PM +0100, Marek Szyprowski wrote:

>> This reverts commit 1874619a7df4b14b23b14877e705ae15325773e3.

>>

>> That patch broke IOMMU support for devices, which fails to probe for the

>> first time and use deferred probe approach. When non-NULL dma_ops is set

>> in arm_iommu_detach_device(), the given device later ignored by

>> arch_setup_dma_ops() and stays with non-IOMMU dma_ops.

>>

>> Reported-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>

>> Fixes: 1874619a7df4 "ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach_device()"

>> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

>> ---

>>   arch/arm/mm/dma-mapping.c | 12 ++++++------

>>   1 file changed, 6 insertions(+), 6 deletions(-)

> 

> Can you point out exactly what drivers break because of this change? We

> need to find a solution that works for everyone. Reverting is only

> marginally useful because somebody will just end up wanting to revert

> the revert because a different driver is now broken.


At first glance, it sounds like what we really want is for 
arch_teardown_iommu_ops() to completely clear any ops that 
arch_setup_dma_ops() installed - does the below suffice?

Robin.

----->8-----
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index f1e2922e447c..1e3e08a1c456 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -2390,4 +2390,6 @@ void arch_teardown_dma_ops(struct device *dev)
  		return;

  	arm_teardown_iommu_dma_ops(dev);
+	/* Let arch_setup_dma_ops() start again from scratch upon re-probe */
+	set_dma_ops(dev, NULL);
  }
Tobias Jakobi Jan. 14, 2019, 8:20 p.m. UTC | #3 
Hello everyone,

first of all thanks to Marek for looking into this.

@Robin: This works for me. The drivers now probe and bind correctly again.

With best wishes,
Tobias

Robin Murphy wrote:
> On 14/01/2019 16:09, Thierry Reding wrote:

>> On Mon, Jan 14, 2019 at 02:22:40PM +0100, Marek Szyprowski wrote:

>>> This reverts commit 1874619a7df4b14b23b14877e705ae15325773e3.

>>>

>>> That patch broke IOMMU support for devices, which fails to probe for the

>>> first time and use deferred probe approach. When non-NULL dma_ops is set

>>> in arm_iommu_detach_device(), the given device later ignored by

>>> arch_setup_dma_ops() and stays with non-IOMMU dma_ops.

>>>

>>> Reported-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>

>>> Fixes: 1874619a7df4 "ARM: dma-mapping: Set proper DMA ops in

>>> arm_iommu_detach_device()"

>>> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

>>> ---

>>>   arch/arm/mm/dma-mapping.c | 12 ++++++------

>>>   1 file changed, 6 insertions(+), 6 deletions(-)

>>

>> Can you point out exactly what drivers break because of this change? We

>> need to find a solution that works for everyone. Reverting is only

>> marginally useful because somebody will just end up wanting to revert

>> the revert because a different driver is now broken.

> 

> At first glance, it sounds like what we really want is for

> arch_teardown_iommu_ops() to completely clear any ops that arch_setup_dma_ops()

> installed - does the below suffice?

> 

> Robin.

> 

> ----->8-----

> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c

> index f1e2922e447c..1e3e08a1c456 100644

> --- a/arch/arm/mm/dma-mapping.c

> +++ b/arch/arm/mm/dma-mapping.c

> @@ -2390,4 +2390,6 @@ void arch_teardown_dma_ops(struct device *dev)

>          return;

> 

>      arm_teardown_iommu_dma_ops(dev);

> +    /* Let arch_setup_dma_ops() start again from scratch upon re-probe */

> +    set_dma_ops(dev, NULL);

>  }
Thierry Reding Jan. 15, 2019, 3:29 p.m. UTC | #4 
On Mon, Jan 14, 2019 at 04:38:20PM +0000, Robin Murphy wrote:
> On 14/01/2019 16:09, Thierry Reding wrote:

> > On Mon, Jan 14, 2019 at 02:22:40PM +0100, Marek Szyprowski wrote:

> > > This reverts commit 1874619a7df4b14b23b14877e705ae15325773e3.

> > > 

> > > That patch broke IOMMU support for devices, which fails to probe for the

> > > first time and use deferred probe approach. When non-NULL dma_ops is set

> > > in arm_iommu_detach_device(), the given device later ignored by

> > > arch_setup_dma_ops() and stays with non-IOMMU dma_ops.

> > > 

> > > Reported-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>

> > > Fixes: 1874619a7df4 "ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach_device()"

> > > Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

> > > ---

> > >   arch/arm/mm/dma-mapping.c | 12 ++++++------

> > >   1 file changed, 6 insertions(+), 6 deletions(-)

> > 

> > Can you point out exactly what drivers break because of this change? We

> > need to find a solution that works for everyone. Reverting is only

> > marginally useful because somebody will just end up wanting to revert

> > the revert because a different driver is now broken.

> 

> At first glance, it sounds like what we really want is for

> arch_teardown_iommu_ops() to completely clear any ops that

> arch_setup_dma_ops() installed - does the below suffice?

> 

> Robin.

> 

> ----->8-----

> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c

> index f1e2922e447c..1e3e08a1c456 100644

> --- a/arch/arm/mm/dma-mapping.c

> +++ b/arch/arm/mm/dma-mapping.c

> @@ -2390,4 +2390,6 @@ void arch_teardown_dma_ops(struct device *dev)

>  		return;

> 

>  	arm_teardown_iommu_dma_ops(dev);

> +	/* Let arch_setup_dma_ops() start again from scratch upon re-probe */

> +	set_dma_ops(dev, NULL);

>  }


Seems to work fine on Tegra:

Tested-by: Thierry Reding <treding@nvidia.com>
Marek Szyprowski Jan. 16, 2019, 10:36 a.m. UTC | #5 
Hi Robin,

On 2019-01-14 17:38, Robin Murphy wrote:
> On 14/01/2019 16:09, Thierry Reding wrote:

>> On Mon, Jan 14, 2019 at 02:22:40PM +0100, Marek Szyprowski wrote:

>>> This reverts commit 1874619a7df4b14b23b14877e705ae15325773e3.

>>>

>>> That patch broke IOMMU support for devices, which fails to probe for

>>> the

>>> first time and use deferred probe approach. When non-NULL dma_ops is

>>> set

>>> in arm_iommu_detach_device(), the given device later ignored by

>>> arch_setup_dma_ops() and stays with non-IOMMU dma_ops.

>>>

>>> Reported-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>

>>> Fixes: 1874619a7df4 "ARM: dma-mapping: Set proper DMA ops in

>>> arm_iommu_detach_device()"

>>> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

>>> ---

>>>   arch/arm/mm/dma-mapping.c | 12 ++++++------

>>>   1 file changed, 6 insertions(+), 6 deletions(-)

>>

>> Can you point out exactly what drivers break because of this change? We

>> need to find a solution that works for everyone. Reverting is only

>> marginally useful because somebody will just end up wanting to revert

>> the revert because a different driver is now broken.

>

> At first glance, it sounds like what we really want is for

> arch_teardown_iommu_ops() to completely clear any ops that

> arch_setup_dma_ops() installed - does the below suffice?


I've initially also thought about similar fix, but then I found the
commit 1874619a7df4b14b23b14877e705ae15325773e3, which was the source of
this problem.

Robin: do you plan to send this fix as a complete patch or do you want
me to resend it with the above commit message and your's suggested-by?

>

> Robin.

>

> ----->8-----

> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c

> index f1e2922e447c..1e3e08a1c456 100644

> --- a/arch/arm/mm/dma-mapping.c

> +++ b/arch/arm/mm/dma-mapping.c

> @@ -2390,4 +2390,6 @@ void arch_teardown_dma_ops(struct device *dev)

>          return;

>

>      arm_teardown_iommu_dma_ops(dev);

> +    /* Let arch_setup_dma_ops() start again from scratch upon

> re-probe */

> +    set_dma_ops(dev, NULL);

>  }

>

>

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland
diff mbox series

Patch

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 3c8534904209..5827a89b7de1 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1145,11 +1145,6 @@  int arm_dma_supported(struct device *dev, u64 mask)
 	return __dma_supported(dev, mask, false);
 }
 
-static const struct dma_map_ops *arm_get_dma_map_ops(bool coherent)
-{
-	return coherent ? &arm_coherent_dma_ops : &arm_dma_ops;
-}
-
 #ifdef CONFIG_ARM_DMA_USE_IOMMU
 
 static int __dma_info_to_prot(enum dma_data_direction dir, unsigned long attrs)
@@ -2294,7 +2289,7 @@  void arm_iommu_detach_device(struct device *dev)
 	iommu_detach_device(mapping->domain, dev);
 	kref_put(&mapping->kref, release_iommu_mapping);
 	to_dma_iommu_mapping(dev) = NULL;
-	set_dma_ops(dev, arm_get_dma_map_ops(dev->archdata.dma_coherent));
+	set_dma_ops(dev, NULL);
 
 	pr_debug("Detached IOMMU controller from %s device.\n", dev_name(dev));
 }
@@ -2355,6 +2350,11 @@  static void arm_teardown_iommu_dma_ops(struct device *dev) { }
 
 #endif	/* CONFIG_ARM_DMA_USE_IOMMU */
 
+static const struct dma_map_ops *arm_get_dma_map_ops(bool coherent)
+{
+	return coherent ? &arm_coherent_dma_ops : &arm_dma_ops;
+}
+
 void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
 			const struct iommu_ops *iommu, bool coherent)
 {