[PATCH] Revert "ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach

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* [PATCH] Revert "ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach_device()"
       [not found] <CGME20190114132250eucas1p2abdf2f36bad3554e37dfbf40e539f594@eucas1p2.samsung.com>
@ 2019-01-14 13:22 ` Marek Szyprowski
  2019-01-14 16:09   ` Thierry Reding
  0 siblings, 1 reply; 6+ messages in thread
From: Marek Szyprowski @ 2019-01-14 13:22 UTC (permalink / raw)
  To: iommu, linux-kernel, linux-arm-kernel
  Cc: Bartlomiej Zolnierkiewicz, Tobias Jakobi, Russell King,
	Ben Skeggs, Thierry Reding, Robin Murphy, Christoph Hellwig,
	Marek Szyprowski

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(-)

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)
 {
-- 
2.17.1


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^ permalink raw reply related	[flat|nested] 6+ messages in thread

* Re: [PATCH] Revert "ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach_device()"
  2019-01-14 13:22 ` [PATCH] Revert "ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach_device()" Marek Szyprowski
@ 2019-01-14 16:09   ` Thierry Reding
  2019-01-14 16:38     ` Robin Murphy
  0 siblings, 1 reply; 6+ messages in thread
From: Thierry Reding @ 2019-01-14 16:09 UTC (permalink / raw)
  To: Marek Szyprowski
  Cc: Bartlomiej Zolnierkiewicz, Russell King, linux-kernel,
	Tobias Jakobi, iommu, Ben Skeggs, Robin Murphy, Christoph Hellwig,
	linux-arm-kernel


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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

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^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] Revert "ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach_device()"
  2019-01-14 16:09   ` Thierry Reding
@ 2019-01-14 16:38     ` Robin Murphy
  2019-01-14 20:20       ` Tobias Jakobi
                         ` (2 more replies)
  0 siblings, 3 replies; 6+ messages in thread
From: Robin Murphy @ 2019-01-14 16:38 UTC (permalink / raw)
  To: Thierry Reding, Marek Szyprowski
  Cc: Bartlomiej Zolnierkiewicz, Russell King, linux-kernel,
	Tobias Jakobi, iommu, Ben Skeggs, Christoph Hellwig,
	linux-arm-kernel

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);
  }

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^ permalink raw reply related	[flat|nested] 6+ messages in thread

* Re: [PATCH] Revert "ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach_device()"
  2019-01-14 16:38     ` Robin Murphy
@ 2019-01-14 20:20       ` Tobias Jakobi
  2019-01-15 15:29       ` Thierry Reding
  2019-01-16 10:36       ` Marek Szyprowski
  2 siblings, 0 replies; 6+ messages in thread
From: Tobias Jakobi @ 2019-01-14 20:20 UTC (permalink / raw)
  To: Robin Murphy, Thierry Reding, Marek Szyprowski
  Cc: Bartlomiej Zolnierkiewicz, Russell King, linux-kernel, iommu,
	Ben Skeggs, Christoph Hellwig, linux-arm-kernel

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);
>  }


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^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] Revert "ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach_device()"
  2019-01-14 16:38     ` Robin Murphy
  2019-01-14 20:20       ` Tobias Jakobi
@ 2019-01-15 15:29       ` Thierry Reding
  2019-01-16 10:36       ` Marek Szyprowski
  2 siblings, 0 replies; 6+ messages in thread
From: Thierry Reding @ 2019-01-15 15:29 UTC (permalink / raw)
  To: Robin Murphy
  Cc: Bartlomiej Zolnierkiewicz, Russell King, linux-kernel,
	Tobias Jakobi, iommu, Ben Skeggs, Christoph Hellwig,
	linux-arm-kernel, Marek Szyprowski


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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>

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^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] Revert "ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach_device()"
  2019-01-14 16:38     ` Robin Murphy
  2019-01-14 20:20       ` Tobias Jakobi
  2019-01-15 15:29       ` Thierry Reding
@ 2019-01-16 10:36       ` Marek Szyprowski
  2 siblings, 0 replies; 6+ messages in thread
From: Marek Szyprowski @ 2019-01-16 10:36 UTC (permalink / raw)
  To: Robin Murphy, Thierry Reding
  Cc: Bartlomiej Zolnierkiewicz, Russell King, linux-kernel,
	Tobias Jakobi, iommu, Ben Skeggs, Christoph Hellwig,
	linux-arm-kernel

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


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     [not found] <CGME20190114132250eucas1p2abdf2f36bad3554e37dfbf40e539f594@eucas1p2.samsung.com>
2019-01-14 13:22 ` [PATCH] Revert "ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach_device()" Marek Szyprowski
2019-01-14 16:09   ` Thierry Reding
2019-01-14 16:38     ` Robin Murphy
2019-01-14 20:20       ` Tobias Jakobi
2019-01-15 15:29       ` Thierry Reding
2019-01-16 10:36       ` Marek Szyprowski

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