Re: [PATCH v5 2/4] lib: devres: add a helper function for ioremap_uc

[Tuowen Zhao]

Sorry, patches in this set should have tag # v4.19+

Should I resubmit a set with the correct tags?

Tuowen

[PATCH v5 2/4] lib: devres: add a helper function for ioremap_uc

[Tuowen Zhao]

Implement a resource managed strongly uncachable ioremap function.

Cc: 
Tested-by: AceLan Kao 
Signed-off-by: Tuowen Zhao 
Acked-by: Mika Westerberg 
Acked-by: Andy Shevchenko 
Acked-by: Luis Chamberlain 
Acked-for-MFD-by: Lee Jones 
---
 include/linux/io.h |  2 ++
 lib/devres.c   | 19 +++
 2 files changed, 21 insertions(+)

diff --git a/include/linux/io.h b/include/linux/io.h
index accac822336a..a59834bc0a11 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -64,6 +64,8 @@ static inline void devm_ioport_unmap(struct device *dev, void 
__iomem *addr)
 
 void __iomem *devm_ioremap(struct device *dev, resource_size_t offset,
   resource_size_t size);
+void __iomem *devm_ioremap_uc(struct device *dev, resource_size_t offset,
+  resource_size_t size);
 void __iomem *devm_ioremap_nocache(struct device *dev, resource_size_t offset,
   resource_size_t size);
 void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset,
diff --git a/lib/devres.c b/lib/devres.c
index 6a0e9bd6524a..17624d35e82d 100644
--- a/lib/devres.c
+++ b/lib/devres.c
@@ -9,6 +9,7 @@
 enum devm_ioremap_type {
DEVM_IOREMAP = 0,
DEVM_IOREMAP_NC,
+   DEVM_IOREMAP_UC,
DEVM_IOREMAP_WC,
 };
 
@@ -39,6 +40,9 @@ static void __iomem *__devm_ioremap(struct device *dev, 
resource_size_t offset,
case DEVM_IOREMAP_NC:
addr = ioremap_nocache(offset, size);
break;
+   case DEVM_IOREMAP_UC:
+   addr = ioremap_uc(offset, size);
+   break;
case DEVM_IOREMAP_WC:
addr = ioremap_wc(offset, size);
break;
@@ -68,6 +72,21 @@ void __iomem *devm_ioremap(struct device *dev, 
resource_size_t offset,
 }
 EXPORT_SYMBOL(devm_ioremap);
 
+/**
+ * devm_ioremap_uc - Managed ioremap_uc()
+ * @dev: Generic device to remap IO address for
+ * @offset: Resource address to map
+ * @size: Size of map
+ *
+ * Managed ioremap_uc().  Map is automatically unmapped on driver detach.
+ */
+void __iomem *devm_ioremap_uc(struct device *dev, resource_size_t offset,
+ resource_size_t size)
+{
+   return __devm_ioremap(dev, offset, size, DEVM_IOREMAP_UC);
+}
+EXPORT_SYMBOL_GPL(devm_ioremap_uc);
+
 /**
  * devm_ioremap_nocache - Managed ioremap_nocache()
  * @dev: Generic device to remap IO address for
-- 
2.23.0

[PATCH v5 4/4] docs: driver-model: add devm_ioremap_uc

[Tuowen Zhao]

Signed-off-by: Tuowen Zhao 
---
 Documentation/driver-api/driver-model/devres.rst | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/driver-api/driver-model/devres.rst 
b/Documentation/driver-api/driver-model/devres.rst
index a100bef54952..92628fdc2f11 100644
--- a/Documentation/driver-api/driver-model/devres.rst
+++ b/Documentation/driver-api/driver-model/devres.rst
@@ -314,6 +314,7 @@ IOMAP
   devm_ioport_unmap()
   devm_ioremap()
   devm_ioremap_nocache()
+  devm_ioremap_uc()
   devm_ioremap_wc()
   devm_ioremap_resource() : checks resource, requests memory region, ioremaps
   devm_iounmap()
-- 
2.23.0

[PATCH v5 3/4] mfd: intel-lpss: use devm_ioremap_uc for MMIO

[Tuowen Zhao]

Some BIOS erroneously specifies write-combining BAR for intel-lpss-pci
in MTRR. This will cause the system to hang during boot. If possible,
this bug could be corrected with a firmware update.

This patch use devm_ioremap_uc to overwrite/ignore the MTRR settings
by forcing the use of strongly uncachable pages for intel-lpss.

The BIOS bug is present on Dell XPS 13 7390 2-in-1:

[0.001734]   5 base 40 mask 60 write-combining

40-7f : PCI Bus :00
  40-400fff : :00:02.0 (i915)
  401000-401fff : :00:15.0 (intel-lpss-pci)

Link: https://bugzilla.kernel.org/show_bug.cgi?id=203485
Cc: 
Tested-by: AceLan Kao 
Signed-off-by: Tuowen Zhao 
Acked-by: Mika Westerberg 
Acked-by: Andy Shevchenko 
Acked-for-MFD-by: Lee Jones 
---
 drivers/mfd/intel-lpss.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mfd/intel-lpss.c b/drivers/mfd/intel-lpss.c
index bfe4ff337581..b0f0781a6b9c 100644
--- a/drivers/mfd/intel-lpss.c
+++ b/drivers/mfd/intel-lpss.c
@@ -384,7 +384,7 @@ int intel_lpss_probe(struct device *dev,
if (!lpss)
return -ENOMEM;
 
-   lpss->priv = devm_ioremap(dev, info->mem->start + LPSS_PRIV_OFFSET,
+   lpss->priv = devm_ioremap_uc(dev, info->mem->start + LPSS_PRIV_OFFSET,
  LPSS_PRIV_SIZE);
if (!lpss->priv)
return -ENOMEM;
-- 
2.23.0

[PATCH v5 1/4] sparc64: implement ioremap_uc

[Tuowen Zhao]

On sparc64, the whole physical IO address space is accessible using
physically addressed loads and stores. *_uc does nothing like the
others.

Cc: 
Reported-by: kbuild test robot 
Signed-off-by: Tuowen Zhao 
---
 arch/sparc/include/asm/io_64.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/sparc/include/asm/io_64.h b/arch/sparc/include/asm/io_64.h
index 688911051b44..f4afa301954a 100644
--- a/arch/sparc/include/asm/io_64.h
+++ b/arch/sparc/include/asm/io_64.h
@@ -407,6 +407,7 @@ static inline void __iomem *ioremap(unsigned long offset, 
unsigned long size)
 }
 
 #define ioremap_nocache(X,Y)   ioremap((X),(Y))
+#define ioremap_uc(X,Y)ioremap((X),(Y))
 #define ioremap_wc(X,Y)ioremap((X),(Y))
 #define ioremap_wt(X,Y)ioremap((X),(Y))
 
-- 
2.23.0

[PATCH v5 0/4] Fix MTRR bug for intel-lpss-pci

[Tuowen Zhao]

Some BIOS erroneously specifies write-combining BAR for intel-lpss-pci
in MTRR. This will cause the system to hang during boot. If possible,
this bug could be corrected with a firmware update.

Previous version: https://lkml.org/lkml/2019/10/14/575

Changes from previous version:

 * implement ioremap_uc for sparc64
 * split docs changes to not CC stable (doc location moved since 5.3)

Tuowen Zhao (4):
  sparc64: implement ioremap_uc
  lib: devres: add a helper function for ioremap_uc
  mfd: intel-lpss: use devm_ioremap_uc for MMIO
  docs: driver-model: add devm_ioremap_uc

 .../driver-api/driver-model/devres.rst|  1 +
 arch/sparc/include/asm/io_64.h|  1 +
 drivers/mfd/intel-lpss.c  |  2 +-
 include/linux/io.h|  2 ++
 lib/devres.c  | 19 +++
 5 files changed, 24 insertions(+), 1 deletion(-)

-- 
2.23.0

Re: [PATCH v4 1/2] lib: devres: add a helper function for ioremap_uc

[Tuowen Zhao]

On Wed, 2019-10-16 at 12:56 +, Luis Chamberlain wrote:
> Indeed, can you add that? If you are not comfortable the way to leave
> behind lazy architectures is the HAS_FOO feature and then have your
> driver require that or depend on the archs that support this. This
> allows non-lazy architecturess to move forward with life.
> 
>   Luis

Upon close examination, the issue seems easy to fix. Going to submit a
new set shortly.

sparc64 and hexagon don't have ioremap_uc defined. Hexagon also doesn't
have ioremap_wc but didn't report an issue before so devm_ioremap won't
have an problem.

Interestingly tho, majority of the archs include ,
thus having prototypes. These two archs and a few others don't. I'm
wondering if including the prototypes is actually the recommended
practice.

Tuowen

Re: [PATCH v4 1/2] lib: devres: add a helper function for ioremap_uc

[Tuowen Zhao]

On Tue, 2019-10-15 at 02:46 +0800, kbuild test robot wrote:
> -O ~/bin/make.cross
> chmod +x ~/bin/make.cross
> # save the attached .config to linux build tree
> GCC_VERSION=7.4.0 make.cross ARCH=sparc64 

Oops, I'm not sure how would we best fix this. Clearly the patch is not
intended for sparc64. Maybe adding devm_ioremap_uc is rather not safe
right now.

Although, We could declare dummies for these architectures like it has
been for powerpc.

I just noticed another driver having this issue, and fixed with direct
calls to ioremap_uc().

3cc2dac5be3f2: drivers/video/fbdev/atyfb: Replace MTRR UC hole with
strong UC

Tuowen

[PATCH v4 1/2] lib: devres: add a helper function for ioremap_uc

[Tuowen Zhao]

Implement a resource managed strongly uncachable ioremap function.

Cc: 
Tested-by: AceLan Kao 
Signed-off-by: Tuowen Zhao 
Acked-by: Mika Westerberg 
Acked-by: Andy Shevchenko 
Acked-by: Luis Chamberlain 
Acked-for-MFD-by: Lee Jones 
---
Changes from previous version:

  * Add Cc stable

 .../driver-api/driver-model/devres.rst|  1 +
 include/linux/io.h|  2 ++
 lib/devres.c  | 19 +++
 3 files changed, 22 insertions(+)

diff --git a/Documentation/driver-api/driver-model/devres.rst 
b/Documentation/driver-api/driver-model/devres.rst
index a100bef54952..92628fdc2f11 100644
--- a/Documentation/driver-api/driver-model/devres.rst
+++ b/Documentation/driver-api/driver-model/devres.rst
@@ -314,6 +314,7 @@ IOMAP
   devm_ioport_unmap()
   devm_ioremap()
   devm_ioremap_nocache()
+  devm_ioremap_uc()
   devm_ioremap_wc()
   devm_ioremap_resource() : checks resource, requests memory region, ioremaps
   devm_iounmap()
diff --git a/include/linux/io.h b/include/linux/io.h
index accac822336a..a59834bc0a11 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -64,6 +64,8 @@ static inline void devm_ioport_unmap(struct device *dev, void 
__iomem *addr)
 
 void __iomem *devm_ioremap(struct device *dev, resource_size_t offset,
   resource_size_t size);
+void __iomem *devm_ioremap_uc(struct device *dev, resource_size_t offset,
+  resource_size_t size);
 void __iomem *devm_ioremap_nocache(struct device *dev, resource_size_t offset,
   resource_size_t size);
 void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset,
diff --git a/lib/devres.c b/lib/devres.c
index 6a0e9bd6524a..17624d35e82d 100644
--- a/lib/devres.c
+++ b/lib/devres.c
@@ -9,6 +9,7 @@
 enum devm_ioremap_type {
DEVM_IOREMAP = 0,
DEVM_IOREMAP_NC,
+   DEVM_IOREMAP_UC,
DEVM_IOREMAP_WC,
 };
 
@@ -39,6 +40,9 @@ static void __iomem *__devm_ioremap(struct device *dev, 
resource_size_t offset,
case DEVM_IOREMAP_NC:
addr = ioremap_nocache(offset, size);
break;
+   case DEVM_IOREMAP_UC:
+   addr = ioremap_uc(offset, size);
+   break;
case DEVM_IOREMAP_WC:
addr = ioremap_wc(offset, size);
break;
@@ -68,6 +72,21 @@ void __iomem *devm_ioremap(struct device *dev, 
resource_size_t offset,
 }
 EXPORT_SYMBOL(devm_ioremap);
 
+/**
+ * devm_ioremap_uc - Managed ioremap_uc()
+ * @dev: Generic device to remap IO address for
+ * @offset: Resource address to map
+ * @size: Size of map
+ *
+ * Managed ioremap_uc().  Map is automatically unmapped on driver detach.
+ */
+void __iomem *devm_ioremap_uc(struct device *dev, resource_size_t offset,
+ resource_size_t size)
+{
+   return __devm_ioremap(dev, offset, size, DEVM_IOREMAP_UC);
+}
+EXPORT_SYMBOL_GPL(devm_ioremap_uc);
+
 /**
  * devm_ioremap_nocache - Managed ioremap_nocache()
  * @dev: Generic device to remap IO address for
-- 
2.23.0

[PATCH v4 2/2] mfd: intel-lpss: use devm_ioremap_uc for MMIO

[Tuowen Zhao]

Some BIOS erroneously specifies write-combining BAR for intel-lpss-pci
in MTRR. This will cause the system to hang during boot. If possible,
this bug could be corrected with a firmware update.

This patch use devm_ioremap_uc to overwrite/ignore the MTRR settings
by forcing the use of strongly uncachable pages for intel-lpss.

The BIOS bug is present on Dell XPS 13 7390 2-in-1:

[0.001734]   5 base 40 mask 60 write-combining

40-7f : PCI Bus :00
  40-400fff : :00:02.0 (i915)
  401000-401fff : :00:15.0 (intel-lpss-pci)

Link: https://bugzilla.kernel.org/show_bug.cgi?id=203485
Cc: 
Tested-by: AceLan Kao 
Signed-off-by: Tuowen Zhao 
Acked-by: Mika Westerberg 
Acked-by: Andy Shevchenko 
Acked-for-MFD-by: Lee Jones 
---
 drivers/mfd/intel-lpss.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mfd/intel-lpss.c b/drivers/mfd/intel-lpss.c
index bfe4ff337581..b0f0781a6b9c 100644
--- a/drivers/mfd/intel-lpss.c
+++ b/drivers/mfd/intel-lpss.c
@@ -384,7 +384,7 @@ int intel_lpss_probe(struct device *dev,
if (!lpss)
return -ENOMEM;
 
-   lpss->priv = devm_ioremap(dev, info->mem->start + LPSS_PRIV_OFFSET,
+   lpss->priv = devm_ioremap_uc(dev, info->mem->start + LPSS_PRIV_OFFSET,
  LPSS_PRIV_SIZE);
if (!lpss->priv)
return -ENOMEM;
-- 
2.23.0

[PATCH v3 2/2] mfd: intel-lpss: use devm_ioremap_uc for MMIO

[Tuowen Zhao]

Some BIOS erroneously specifies write-combining BAR for intel-lpss-pci
in MTRR. This will cause the system to hang during boot. If possible,
this bug could be corrected with a firmware update.

This patch use devm_ioremap_uc to overwrite/ignore the MTRR settings
by forcing the use of strongly uncachable pages for intel-lpss.

The BIOS bug is present on Dell XPS 13 7390 2-in-1:

[0.001734]   5 base 40 mask 60 write-combining

40-7f : PCI Bus :00
  40-400fff : :00:02.0 (i915)
  401000-401fff : :00:15.0 (intel-lpss-pci)

Link: https://bugzilla.kernel.org/show_bug.cgi?id=203485
Tested-by: AceLan Kao 
Signed-off-by: Tuowen Zhao 
Acked-by: Mika Westerberg 
Acked-by: Andy Shevchenko 
---
 drivers/mfd/intel-lpss.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mfd/intel-lpss.c b/drivers/mfd/intel-lpss.c
index bfe4ff337581..b0f0781a6b9c 100644
--- a/drivers/mfd/intel-lpss.c
+++ b/drivers/mfd/intel-lpss.c
@@ -384,7 +384,7 @@ int intel_lpss_probe(struct device *dev,
if (!lpss)
return -ENOMEM;
 
-   lpss->priv = devm_ioremap(dev, info->mem->start + LPSS_PRIV_OFFSET,
+   lpss->priv = devm_ioremap_uc(dev, info->mem->start + LPSS_PRIV_OFFSET,
  LPSS_PRIV_SIZE);
if (!lpss->priv)
return -ENOMEM;
-- 
2.23.0

[PATCH v3 1/2] lib: devres: add a helper function for ioremap_uc

[Tuowen Zhao]

Implement a resource managed strongly uncachable ioremap function.

Tested-by: AceLan Kao 
Signed-off-by: Tuowen Zhao 
Acked-by: Mika Westerberg 
Acked-by: Andy Shevchenko 
---
Changes from previous version:

  * Split the patch in 2
  * Use GPL export for devm_ioremap_uc
  * Add entry to devres doc

 .../driver-api/driver-model/devres.rst|  1 +
 include/linux/io.h|  2 ++
 lib/devres.c  | 19 +++
 3 files changed, 22 insertions(+)

diff --git a/Documentation/driver-api/driver-model/devres.rst 
b/Documentation/driver-api/driver-model/devres.rst
index a100bef54952..92628fdc2f11 100644
--- a/Documentation/driver-api/driver-model/devres.rst
+++ b/Documentation/driver-api/driver-model/devres.rst
@@ -314,6 +314,7 @@ IOMAP
   devm_ioport_unmap()
   devm_ioremap()
   devm_ioremap_nocache()
+  devm_ioremap_uc()
   devm_ioremap_wc()
   devm_ioremap_resource() : checks resource, requests memory region, ioremaps
   devm_iounmap()
diff --git a/include/linux/io.h b/include/linux/io.h
index accac822336a..a59834bc0a11 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -64,6 +64,8 @@ static inline void devm_ioport_unmap(struct device *dev, void 
__iomem *addr)
 
 void __iomem *devm_ioremap(struct device *dev, resource_size_t offset,
   resource_size_t size);
+void __iomem *devm_ioremap_uc(struct device *dev, resource_size_t offset,
+  resource_size_t size);
 void __iomem *devm_ioremap_nocache(struct device *dev, resource_size_t offset,
   resource_size_t size);
 void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset,
diff --git a/lib/devres.c b/lib/devres.c
index 6a0e9bd6524a..17624d35e82d 100644
--- a/lib/devres.c
+++ b/lib/devres.c
@@ -9,6 +9,7 @@
 enum devm_ioremap_type {
DEVM_IOREMAP = 0,
DEVM_IOREMAP_NC,
+   DEVM_IOREMAP_UC,
DEVM_IOREMAP_WC,
 };
 
@@ -39,6 +40,9 @@ static void __iomem *__devm_ioremap(struct device *dev, 
resource_size_t offset,
case DEVM_IOREMAP_NC:
addr = ioremap_nocache(offset, size);
break;
+   case DEVM_IOREMAP_UC:
+   addr = ioremap_uc(offset, size);
+   break;
case DEVM_IOREMAP_WC:
addr = ioremap_wc(offset, size);
break;
@@ -68,6 +72,21 @@ void __iomem *devm_ioremap(struct device *dev, 
resource_size_t offset,
 }
 EXPORT_SYMBOL(devm_ioremap);
 
+/**
+ * devm_ioremap_uc - Managed ioremap_uc()
+ * @dev: Generic device to remap IO address for
+ * @offset: Resource address to map
+ * @size: Size of map
+ *
+ * Managed ioremap_uc().  Map is automatically unmapped on driver detach.
+ */
+void __iomem *devm_ioremap_uc(struct device *dev, resource_size_t offset,
+ resource_size_t size)
+{
+   return __devm_ioremap(dev, offset, size, DEVM_IOREMAP_UC);
+}
+EXPORT_SYMBOL_GPL(devm_ioremap_uc);
+
 /**
  * devm_ioremap_nocache - Managed ioremap_nocache()
  * @dev: Generic device to remap IO address for
-- 
2.23.0

[PATCH v2] mfd: intel-lpss: use devm_ioremap_uc for MMIO

[Tuowen Zhao]

Some BIOS erroneously specifies write-combining BAR for intel-lpss-pci
in MTRR. This will cause the system to hang during boot. If possible,
this bug could be corrected with a firmware update.

This patch adds devm_ioremap_uc as a new managed wrapper to ioremap_uc
and with it overwrite the MTRR settings to force the use of strongly
uncachable pages for intel-lpss.

The BIOS bug is present on Dell XPS 13 7390 2-in-1:

[0.001734]   5 base 40 mask 60 write-combining

40-7f : PCI Bus :00
  40-400fff : :00:02.0 (i915)
  401000-401fff : :00:15.0 (intel-lpss-pci)

Link: https://bugzilla.kernel.org/show_bug.cgi?id=203485
Signed-off-by: Tuowen Zhao 
---
Changes from previous version:

  * changed commit message

 drivers/mfd/intel-lpss.c |  2 +-
 include/linux/io.h   |  2 ++
 lib/devres.c | 19 +++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/mfd/intel-lpss.c b/drivers/mfd/intel-lpss.c
index bfe4ff337581..b0f0781a6b9c 100644
--- a/drivers/mfd/intel-lpss.c
+++ b/drivers/mfd/intel-lpss.c
@@ -384,7 +384,7 @@ int intel_lpss_probe(struct device *dev,
if (!lpss)
return -ENOMEM;
 
-   lpss->priv = devm_ioremap(dev, info->mem->start + LPSS_PRIV_OFFSET,
+   lpss->priv = devm_ioremap_uc(dev, info->mem->start + LPSS_PRIV_OFFSET,
  LPSS_PRIV_SIZE);
if (!lpss->priv)
return -ENOMEM;
diff --git a/include/linux/io.h b/include/linux/io.h
index accac822336a..a59834bc0a11 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -64,6 +64,8 @@ static inline void devm_ioport_unmap(struct device *dev, void 
__iomem *addr)
 
 void __iomem *devm_ioremap(struct device *dev, resource_size_t offset,
   resource_size_t size);
+void __iomem *devm_ioremap_uc(struct device *dev, resource_size_t offset,
+  resource_size_t size);
 void __iomem *devm_ioremap_nocache(struct device *dev, resource_size_t offset,
   resource_size_t size);
 void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset,
diff --git a/lib/devres.c b/lib/devres.c
index 6a0e9bd6524a..beb0a064b891 100644
--- a/lib/devres.c
+++ b/lib/devres.c
@@ -9,6 +9,7 @@
 enum devm_ioremap_type {
DEVM_IOREMAP = 0,
DEVM_IOREMAP_NC,
+   DEVM_IOREMAP_UC,
DEVM_IOREMAP_WC,
 };
 
@@ -39,6 +40,9 @@ static void __iomem *__devm_ioremap(struct device *dev, 
resource_size_t offset,
case DEVM_IOREMAP_NC:
addr = ioremap_nocache(offset, size);
break;
+   case DEVM_IOREMAP_UC:
+   addr = ioremap_uc(offset, size);
+   break;
case DEVM_IOREMAP_WC:
addr = ioremap_wc(offset, size);
break;
@@ -68,6 +72,21 @@ void __iomem *devm_ioremap(struct device *dev, 
resource_size_t offset,
 }
 EXPORT_SYMBOL(devm_ioremap);
 
+/**
+ * devm_ioremap_uc - Managed ioremap_uc()
+ * @dev: Generic device to remap IO address for
+ * @offset: Resource address to map
+ * @size: Size of map
+ *
+ * Managed ioremap_uc().  Map is automatically unmapped on driver detach.
+ */
+void __iomem *devm_ioremap_uc(struct device *dev, resource_size_t offset,
+ resource_size_t size)
+{
+   return __devm_ioremap(dev, offset, size, DEVM_IOREMAP_UC);
+}
+EXPORT_SYMBOL(devm_ioremap_uc);
+
 /**
  * devm_ioremap_nocache - Managed ioremap_nocache()
  * @dev: Generic device to remap IO address for
-- 
2.23.0

[PATCH] mfd: intel-lpss: use devm_ioremap_uc for mmio

[Tuowen Zhao]

Write-combining BAR for intel-lpss-pci in MTRR causes system hangs
during boot.

This patch adds devm_ioremap_uc as a new managed wrapper to ioremap_uc
and with it forces the use of strongly uncachable mmio in intel-lpss.

This bahavior is seen on Dell XPS 13 7390 2-in-1:

[0.001734]   5 base 40 mask 60 write-combining

40-7f : PCI Bus :00
  40-400fff : :00:02.0 (i915)
  401000-401fff : :00:15.0 (intel-lpss-pci)

Link: https://bugzilla.kernel.org/show_bug.cgi?id=203485
Signed-off-by: Tuowen Zhao 
---
 drivers/mfd/intel-lpss.c |  2 +-
 include/linux/io.h   |  2 ++
 lib/devres.c | 19 +++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/mfd/intel-lpss.c b/drivers/mfd/intel-lpss.c
index 277f48f1cc1c..06106c9320bb 100644
--- a/drivers/mfd/intel-lpss.c
+++ b/drivers/mfd/intel-lpss.c
@@ -395,7 +395,7 @@ int intel_lpss_probe(struct device *dev,
if (!lpss)
return -ENOMEM;
 
-   lpss->priv = devm_ioremap(dev, info->mem->start + LPSS_PRIV_OFFSET,
+   lpss->priv = devm_ioremap_uc(dev, info->mem->start + LPSS_PRIV_OFFSET,
  LPSS_PRIV_SIZE);
if (!lpss->priv)
return -ENOMEM;
diff --git a/include/linux/io.h b/include/linux/io.h
index accac822336a..a59834bc0a11 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -64,6 +64,8 @@ static inline void devm_ioport_unmap(struct device *dev, void 
__iomem *addr)
 
 void __iomem *devm_ioremap(struct device *dev, resource_size_t offset,
   resource_size_t size);
+void __iomem *devm_ioremap_uc(struct device *dev, resource_size_t offset,
+  resource_size_t size);
 void __iomem *devm_ioremap_nocache(struct device *dev, resource_size_t offset,
   resource_size_t size);
 void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset,
diff --git a/lib/devres.c b/lib/devres.c
index 6a0e9bd6524a..beb0a064b891 100644
--- a/lib/devres.c
+++ b/lib/devres.c
@@ -9,6 +9,7 @@
 enum devm_ioremap_type {
DEVM_IOREMAP = 0,
DEVM_IOREMAP_NC,
+   DEVM_IOREMAP_UC,
DEVM_IOREMAP_WC,
 };
 
@@ -39,6 +40,9 @@ static void __iomem *__devm_ioremap(struct device *dev, 
resource_size_t offset,
case DEVM_IOREMAP_NC:
addr = ioremap_nocache(offset, size);
break;
+   case DEVM_IOREMAP_UC:
+   addr = ioremap_uc(offset, size);
+   break;
case DEVM_IOREMAP_WC:
addr = ioremap_wc(offset, size);
break;
@@ -68,6 +72,21 @@ void __iomem *devm_ioremap(struct device *dev, 
resource_size_t offset,
 }
 EXPORT_SYMBOL(devm_ioremap);
 
+/**
+ * devm_ioremap_uc - Managed ioremap_uc()
+ * @dev: Generic device to remap IO address for
+ * @offset: Resource address to map
+ * @size: Size of map
+ *
+ * Managed ioremap_uc().  Map is automatically unmapped on driver detach.
+ */
+void __iomem *devm_ioremap_uc(struct device *dev, resource_size_t offset,
+ resource_size_t size)
+{
+   return __devm_ioremap(dev, offset, size, DEVM_IOREMAP_UC);
+}
+EXPORT_SYMBOL(devm_ioremap_uc);
+
 /**
  * devm_ioremap_nocache - Managed ioremap_nocache()
  * @dev: Generic device to remap IO address for
-- 
2.23.0