Re: [Nouveau] [RFC v3 02/45] dma-mapping: Use unsigned long for dma_attrs

2016-06-06 Thread Krzysztof Kozlowski 
On 06/03/2016 09:17 AM, Geert Uytterhoeven wrote:
> Hi Krzysztof,
> 
> On Thu, Jun 2, 2016 at 5:39 PM, Krzysztof Kozlowski
>  wrote:
>> --- a/include/linux/dma-mapping.h
>> +++ b/include/linux/dma-mapping.h
>> @@ -5,13 +5,25 @@
> 
>> +/**
>> + * List of possible attributes associated with a DMA mapping. The semantics
>> + * of each attribute should be defined in Documentation/DMA-attributes.txt.
>> + */
>> +#define DMA_ATTR_WRITE_BARRIER (1UL << 1)
> 
> Any particular reason they start at 2, not 1?

No reason. I'll fix this in next version (and trim Cc-list). Anyway the
values of constants won't match old ones but that should not be problem
(unless they are hard-coded somewhere).

Best regards,
Krzysztof


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Re: [Nouveau] [RFC v3 02/45] dma-mapping: Use unsigned long for dma_attrs

2016-06-03 Thread Geert Uytterhoeven 
Hi Krzysztof,

On Thu, Jun 2, 2016 at 5:39 PM, Krzysztof Kozlowski
 wrote:
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -5,13 +5,25 @@

> +/**
> + * List of possible attributes associated with a DMA mapping. The semantics
> + * of each attribute should be defined in Documentation/DMA-attributes.txt.
> + */
> +#define DMA_ATTR_WRITE_BARRIER (1UL << 1)

Any particular reason they start at 2, not 1?

> +#define DMA_ATTR_WEAK_ORDERING (1UL << 2)
> +#define DMA_ATTR_WRITE_COMBINE (1UL << 3)
> +#define DMA_ATTR_NON_CONSISTENT(1UL << 4)
> +#define DMA_ATTR_NO_KERNEL_MAPPING (1UL << 5)
> +#define DMA_ATTR_SKIP_CPU_SYNC (1UL << 6)
> +#define DMA_ATTR_FORCE_CONTIGUOUS  (1UL << 7)
> +#define DMA_ATTR_ALLOC_SINGLE_PAGES(1UL << 8)

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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[Nouveau] [RFC v3 02/45] dma-mapping: Use unsigned long for dma_attrs

2016-06-03 Thread Krzysztof Kozlowski 
The dma-mapping core and the implementations do not change the
DMA attributes passed by pointer.  Thus the pointer can point to const
data.  However the attributes do not have to be a bitfield. Instead
unsigned long will do fine:

1. This is just simpler.  Both in terms of reading the code and setting
   attributes.  Instead of initializing local attributes on the stack
   and passing pointer to it to dma_set_attr(), just set the bits.

2. It brings safeness and checking for const correctness because the
   attributes are passed by value.

Semantic patches for this change (at least most of them):
===
virtual patch
virtual context

@r@
identifier f, attrs;

@@
f(...,
- struct dma_attrs *attrs
+ unsigned long attrs
, ...)
{
...
}

@@
identifier r.f;
@@
f(...,
- NULL
+ 0
 )
===
// Options: --all-includes
virtual patch
virtual context

@r@
identifier f, attrs;
type t;

@@
t f(..., struct dma_attrs *attrs);

@@
identifier r.f;
@@
f(...,
- NULL
+ 0
 )
===

Signed-off-by: Krzysztof Kozlowski 
---
 Documentation/DMA-API.txt|  29 +--
 Documentation/DMA-attributes.txt |   2 +-
 include/linux/dma-attrs.h|  71 -
 include/linux/dma-mapping.h  | 108 +++
 lib/dma-noop.c   |   9 ++--
 5 files changed, 83 insertions(+), 136 deletions(-)
 delete mode 100644 include/linux/dma-attrs.h

diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index 45ef3f279c3b..24f9688bb98a 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -369,35 +369,32 @@ See also dma_map_single().
 dma_addr_t
 dma_map_single_attrs(struct device *dev, void *cpu_addr, size_t size,
 enum dma_data_direction dir,
-struct dma_attrs *attrs)
+unsigned long attrs)
 
 void
 dma_unmap_single_attrs(struct device *dev, dma_addr_t dma_addr,
   size_t size, enum dma_data_direction dir,
-  struct dma_attrs *attrs)
+  unsigned long attrs)
 
 int
 dma_map_sg_attrs(struct device *dev, struct scatterlist *sgl,
 int nents, enum dma_data_direction dir,
-struct dma_attrs *attrs)
+unsigned long attrs)
 
 void
 dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sgl,
   int nents, enum dma_data_direction dir,
-  struct dma_attrs *attrs)
+  unsigned long attrs)
 
 The four functions above are just like the counterpart functions
 without the _attrs suffixes, except that they pass an optional
-struct dma_attrs*.
-
-struct dma_attrs encapsulates a set of "DMA attributes". For the
-definition of struct dma_attrs see linux/dma-attrs.h.
+dma_attrs.
 
 The interpretation of DMA attributes is architecture-specific, and
 each attribute should be documented in Documentation/DMA-attributes.txt.
 
-If struct dma_attrs* is NULL, the semantics of each of these
-functions is identical to those of the corresponding function
+If dma_attrs are 0, the semantics of each of these functions
+is identical to those of the corresponding function
 without the _attrs suffix. As a result dma_map_single_attrs()
 can generally replace dma_map_single(), etc.
 
@@ -405,15 +402,15 @@ As an example of the use of the *_attrs functions, here's 
how
 you could pass an attribute DMA_ATTR_FOO when mapping memory
 for DMA:
 
-#include 
-/* DMA_ATTR_FOO should be defined in linux/dma-attrs.h and
+#include 
+/* DMA_ATTR_FOO should be defined in linux/dma-mapping.h and
  * documented in Documentation/DMA-attributes.txt */
 ...
 
-   DEFINE_DMA_ATTRS(attrs);
-   dma_set_attr(DMA_ATTR_FOO, );
+   unsigned long attr;
+   attr |= DMA_ATTR_FOO;

-   n = dma_map_sg_attrs(dev, sg, nents, DMA_TO_DEVICE, );
+   n = dma_map_sg_attrs(dev, sg, nents, DMA_TO_DEVICE, attr);

 
 Architectures that care about DMA_ATTR_FOO would check for its
@@ -422,7 +419,7 @@ routines, e.g.:
 
 void whizco_dma_map_sg_attrs(struct device *dev, dma_addr_t dma_addr,
 size_t size, enum dma_data_direction dir,
-struct dma_attrs *attrs)
+unsigned long attrs)
 {

int foo =  dma_get_attr(DMA_ATTR_FOO, attrs);
diff --git a/Documentation/DMA-attributes.txt b/Documentation/DMA-attributes.txt
index e8cf9cf873b3..2d455a5cf671 100644
--- a/Documentation/DMA-attributes.txt
+++ b/Documentation/DMA-attributes.txt
@@ -2,7 +2,7 @@
==
 
 This document describes the semantics of the DMA attributes that are
-defined in linux/dma-attrs.h.
+defined in linux/dma-mapping.h.
 
 DMA_ATTR_WRITE_BARRIER
 --
diff --git a/include/linux/dma-attrs.h b/include/linux/dma-attrs.h
deleted file mode 100644
index 5246239a4953..
--- a/include/linux/dma-attrs.h
+++ /dev/null
@@ -1,71 +0,0 @@