Mailing List Archive: [PATCH 2/2] dma-buf: add helpers for attacher dma-parms

[PATCH 2/2] dma-buf: add helpers for attacher dma-parms

Jul 19, 2012, 9:23 AM

Post #1 of 6 (209 views)

From: Rob Clark <rob@ti.com>

Add some helpers to iterate through all attachers and get the most
restrictive segment size/count/boundary.

Signed-off-by: Rob Clark <rob@ti.com>
---
drivers/base/dma-buf.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++
include/linux/dma-buf.h | 19 ++++++++++++++
2 files changed, 82 insertions(+)

diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index 24e88fe..757ee20 100644
--- a/drivers/base/dma-buf.c
+++ b/drivers/base/dma-buf.c
@@ -192,6 +192,69 @@ void dma_buf_put(struct dma_buf *dmabuf)
EXPORT_SYMBOL_GPL(dma_buf_put);

/**
+ * dma_buf_max_seg_size - helper for exporters to get the minimum of
+ * all attached device's max segment size
+ */
+unsigned int dma_buf_max_seg_size(struct dma_buf *dmabuf)
+{
+ struct dma_buf_attachment *attach;
+ unsigned int max = (unsigned int)-1;
+
+ if (WARN_ON(!dmabuf))
+ return 0;
+
+ mutex_lock(&dmabuf->lock);
+ list_for_each_entry(attach, &dmabuf->attachments, node)
+ max = min(max, dma_get_max_seg_size(attach->dev));
+ mutex_unlock(&dmabuf->lock);
+
+ return max;
+}
+EXPORT_SYMBOL_GPL(dma_buf_max_seg_size);
+
+/**
+ * dma_buf_max_seg_count - helper for exporters to get the minimum of
+ * all attached device's max segment count
+ */
+unsigned int dma_buf_max_seg_count(struct dma_buf *dmabuf)
+{
+ struct dma_buf_attachment *attach;
+ unsigned int max = (unsigned int)-1;
+
+ if (WARN_ON(!dmabuf))
+ return 0;
+
+ mutex_lock(&dmabuf->lock);
+ list_for_each_entry(attach, &dmabuf->attachments, node)
+ max = min(max, dma_get_max_seg_count(attach->dev));
+ mutex_unlock(&dmabuf->lock);
+
+ return max;
+}
+EXPORT_SYMBOL_GPL(dma_buf_max_seg_count);
+
+/**
+ * dma_buf_get_seg_boundary - helper for exporters to get the most
+ * restrictive segment alignment of all the attached devices
+ */
+unsigned int dma_buf_get_seg_boundary(struct dma_buf *dmabuf)
+{
+ struct dma_buf_attachment *attach;
+ unsigned int mask = (unsigned int)-1;
+
+ if (WARN_ON(!dmabuf))
+ return 0;
+
+ mutex_lock(&dmabuf->lock);
+ list_for_each_entry(attach, &dmabuf->attachments, node)
+ mask &= dma_get_seg_boundary(attach->dev);
+ mutex_unlock(&dmabuf->lock);
+
+ return mask;
+}
+EXPORT_SYMBOL_GPL(dma_buf_get_seg_boundary);
+
+/**
* dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
* calls attach() of dma_buf_ops to allow device-specific attach functionality
* @dmabuf: [in] buffer to attach device to.
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index eb48f38..9533b9b 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -167,6 +167,10 @@ int dma_buf_fd(struct dma_buf *dmabuf, int flags);
struct dma_buf *dma_buf_get(int fd);
void dma_buf_put(struct dma_buf *dmabuf);

+unsigned int dma_buf_max_seg_size(struct dma_buf *dmabuf);
+unsigned int dma_buf_max_seg_count(struct dma_buf *dmabuf);
+unsigned int dma_buf_get_seg_boundary(struct dma_buf *dmabuf);
+
struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
enum dma_data_direction);
void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
@@ -220,6 +224,21 @@ static inline void dma_buf_put(struct dma_buf *dmabuf)
return;
}

+static inline unsigned int dma_buf_max_seg_size(struct dma_buf *dmabuf)
+{
+ return 0;
+}
+
+static inline unsigned int dma_buf_max_seg_count(struct dma_buf *dmabuf)
+{
+ return 0;
+}
+
+static inline unsigned int dma_buf_get_seg_boundary(struct dma_buf *dmabuf)
+{
+ return 0;
+}
+
static inline struct sg_table *dma_buf_map_attachment(
struct dma_buf_attachment *attach, enum dma_data_direction write)
{
--
1.7.9.5

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Re: [PATCH 2/2] dma-buf: add helpers for attacher dma-parms [ In reply to ]

rob.clark at linaro

Jul 20, 2012, 9:39 AM

Post #2 of 6 (200 views)

Permalink

Fyi, Daniel Vetter had suggested on IRC that it would be cleaner to
have a single helper fxn that most-restrictive union of all attached
device's dma_parms. Really this should include dma_mask and
coherent_dma_mask, I think. But that touches a lot of other places in
the code. If no one objects to the cleanup of moving
dma_mask/coherent_dma_mask into dma_parms, I'll do this first.

So anyways, don't consider this patch yet for inclusion, I'll make an
updated one based on dma_parms..

BR,
-R

On Thu, Jul 19, 2012 at 11:23 AM, Rob Clark <rob.clark@linaro.org> wrote:
> From: Rob Clark <rob@ti.com>
>
> Add some helpers to iterate through all attachers and get the most
> restrictive segment size/count/boundary.
>
> Signed-off-by: Rob Clark <rob@ti.com>
> ---
> drivers/base/dma-buf.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/dma-buf.h | 19 ++++++++++++++
> 2 files changed, 82 insertions(+)
>
> diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
> index 24e88fe..757ee20 100644
> --- a/drivers/base/dma-buf.c
> +++ b/drivers/base/dma-buf.c
> @@ -192,6 +192,69 @@ void dma_buf_put(struct dma_buf *dmabuf)
> EXPORT_SYMBOL_GPL(dma_buf_put);
>
> /**
> + * dma_buf_max_seg_size - helper for exporters to get the minimum of
> + * all attached device's max segment size
> + */
> +unsigned int dma_buf_max_seg_size(struct dma_buf *dmabuf)
> +{
> + struct dma_buf_attachment *attach;
> + unsigned int max = (unsigned int)-1;
> +
> + if (WARN_ON(!dmabuf))
> + return 0;
> +
> + mutex_lock(&dmabuf->lock);
> + list_for_each_entry(attach, &dmabuf->attachments, node)
> + max = min(max, dma_get_max_seg_size(attach->dev));
> + mutex_unlock(&dmabuf->lock);
> +
> + return max;
> +}
> +EXPORT_SYMBOL_GPL(dma_buf_max_seg_size);
> +
> +/**
> + * dma_buf_max_seg_count - helper for exporters to get the minimum of
> + * all attached device's max segment count
> + */
> +unsigned int dma_buf_max_seg_count(struct dma_buf *dmabuf)
> +{
> + struct dma_buf_attachment *attach;
> + unsigned int max = (unsigned int)-1;
> +
> + if (WARN_ON(!dmabuf))
> + return 0;
> +
> + mutex_lock(&dmabuf->lock);
> + list_for_each_entry(attach, &dmabuf->attachments, node)
> + max = min(max, dma_get_max_seg_count(attach->dev));
> + mutex_unlock(&dmabuf->lock);
> +
> + return max;
> +}
> +EXPORT_SYMBOL_GPL(dma_buf_max_seg_count);
> +
> +/**
> + * dma_buf_get_seg_boundary - helper for exporters to get the most
> + * restrictive segment alignment of all the attached devices
> + */
> +unsigned int dma_buf_get_seg_boundary(struct dma_buf *dmabuf)
> +{
> + struct dma_buf_attachment *attach;
> + unsigned int mask = (unsigned int)-1;
> +
> + if (WARN_ON(!dmabuf))
> + return 0;
> +
> + mutex_lock(&dmabuf->lock);
> + list_for_each_entry(attach, &dmabuf->attachments, node)
> + mask &= dma_get_seg_boundary(attach->dev);
> + mutex_unlock(&dmabuf->lock);
> +
> + return mask;
> +}
> +EXPORT_SYMBOL_GPL(dma_buf_get_seg_boundary);
> +
> +/**
> * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
> * calls attach() of dma_buf_ops to allow device-specific attach functionality
> * @dmabuf: [in] buffer to attach device to.
> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
> index eb48f38..9533b9b 100644
> --- a/include/linux/dma-buf.h
> +++ b/include/linux/dma-buf.h
> @@ -167,6 +167,10 @@ int dma_buf_fd(struct dma_buf *dmabuf, int flags);
> struct dma_buf *dma_buf_get(int fd);
> void dma_buf_put(struct dma_buf *dmabuf);
>
> +unsigned int dma_buf_max_seg_size(struct dma_buf *dmabuf);
> +unsigned int dma_buf_max_seg_count(struct dma_buf *dmabuf);
> +unsigned int dma_buf_get_seg_boundary(struct dma_buf *dmabuf);
> +
> struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
> enum dma_data_direction);
> void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
> @@ -220,6 +224,21 @@ static inline void dma_buf_put(struct dma_buf *dmabuf)
> return;
> }
>
> +static inline unsigned int dma_buf_max_seg_size(struct dma_buf *dmabuf)
> +{
> + return 0;
> +}
> +
> +static inline unsigned int dma_buf_max_seg_count(struct dma_buf *dmabuf)
> +{
> + return 0;
> +}
> +
> +static inline unsigned int dma_buf_get_seg_boundary(struct dma_buf *dmabuf)
> +{
> + return 0;
> +}
> +
> static inline struct sg_table *dma_buf_map_attachment(
> struct dma_buf_attachment *attach, enum dma_data_direction write)
> {
> --
> 1.7.9.5
>
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Re: [PATCH 2/2] dma-buf: add helpers for attacher dma-parms [ In reply to ]

sumit.semwal at ti

Aug 5, 2012, 11:37 PM

Post #3 of 6 (188 views)

Permalink

On Fri, Jul 20, 2012 at 10:09 PM, Rob Clark <rob.clark@linaro.org> wrote:
> Fyi, Daniel Vetter had suggested on IRC that it would be cleaner to
> have a single helper fxn that most-restrictive union of all attached
> device's dma_parms. Really this should include dma_mask and
> coherent_dma_mask, I think. But that touches a lot of other places in
> the code. If no one objects to the cleanup of moving
> dma_mask/coherent_dma_mask into dma_parms, I'll do this first.
>
> So anyways, don't consider this patch yet for inclusion, I'll make an
> updated one based on dma_parms..
Hi Rob,
Any news on this patch-set?
>
> BR,
> -R
BR,
~Sumit.
>
> On Thu, Jul 19, 2012 at 11:23 AM, Rob Clark <rob.clark@linaro.org> wrote:
>> From: Rob Clark <rob@ti.com>
>>
>> Add some helpers to iterate through all attachers and get the most
>> restrictive segment size/count/boundary.
>>
>> Signed-off-by: Rob Clark <rob@ti.com>
>> ---
>> drivers/base/dma-buf.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++
>> include/linux/dma-buf.h | 19 ++++++++++++++
>> 2 files changed, 82 insertions(+)
>>
>> diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
>> index 24e88fe..757ee20 100644
>> --- a/drivers/base/dma-buf.c
>> +++ b/drivers/base/dma-buf.c
>> @@ -192,6 +192,69 @@ void dma_buf_put(struct dma_buf *dmabuf)
>> EXPORT_SYMBOL_GPL(dma_buf_put);
>>
>> /**
>> + * dma_buf_max_seg_size - helper for exporters to get the minimum of
>> + * all attached device's max segment size
>> + */
>> +unsigned int dma_buf_max_seg_size(struct dma_buf *dmabuf)
>> +{
>> + struct dma_buf_attachment *attach;
>> + unsigned int max = (unsigned int)-1;
>> +
>> + if (WARN_ON(!dmabuf))
>> + return 0;
>> +
>> + mutex_lock(&dmabuf->lock);
>> + list_for_each_entry(attach, &dmabuf->attachments, node)
>> + max = min(max, dma_get_max_seg_size(attach->dev));
>> + mutex_unlock(&dmabuf->lock);
>> +
>> + return max;
>> +}
>> +EXPORT_SYMBOL_GPL(dma_buf_max_seg_size);
>> +
>> +/**
>> + * dma_buf_max_seg_count - helper for exporters to get the minimum of
>> + * all attached device's max segment count
>> + */
>> +unsigned int dma_buf_max_seg_count(struct dma_buf *dmabuf)
>> +{
>> + struct dma_buf_attachment *attach;
>> + unsigned int max = (unsigned int)-1;
>> +
>> + if (WARN_ON(!dmabuf))
>> + return 0;
>> +
>> + mutex_lock(&dmabuf->lock);
>> + list_for_each_entry(attach, &dmabuf->attachments, node)
>> + max = min(max, dma_get_max_seg_count(attach->dev));
>> + mutex_unlock(&dmabuf->lock);
>> +
>> + return max;
>> +}
>> +EXPORT_SYMBOL_GPL(dma_buf_max_seg_count);
>> +
>> +/**
>> + * dma_buf_get_seg_boundary - helper for exporters to get the most
>> + * restrictive segment alignment of all the attached devices
>> + */
>> +unsigned int dma_buf_get_seg_boundary(struct dma_buf *dmabuf)
>> +{
>> + struct dma_buf_attachment *attach;
>> + unsigned int mask = (unsigned int)-1;
>> +
>> + if (WARN_ON(!dmabuf))
>> + return 0;
>> +
>> + mutex_lock(&dmabuf->lock);
>> + list_for_each_entry(attach, &dmabuf->attachments, node)
>> + mask &= dma_get_seg_boundary(attach->dev);
>> + mutex_unlock(&dmabuf->lock);
>> +
>> + return mask;
>> +}
>> +EXPORT_SYMBOL_GPL(dma_buf_get_seg_boundary);
>> +
>> +/**
>> * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
>> * calls attach() of dma_buf_ops to allow device-specific attach functionality
>> * @dmabuf: [in] buffer to attach device to.
>> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
>> index eb48f38..9533b9b 100644
>> --- a/include/linux/dma-buf.h
>> +++ b/include/linux/dma-buf.h
>> @@ -167,6 +167,10 @@ int dma_buf_fd(struct dma_buf *dmabuf, int flags);
>> struct dma_buf *dma_buf_get(int fd);
>> void dma_buf_put(struct dma_buf *dmabuf);
>>
>> +unsigned int dma_buf_max_seg_size(struct dma_buf *dmabuf);
>> +unsigned int dma_buf_max_seg_count(struct dma_buf *dmabuf);
>> +unsigned int dma_buf_get_seg_boundary(struct dma_buf *dmabuf);
>> +
>> struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
>> enum dma_data_direction);
>> void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
>> @@ -220,6 +224,21 @@ static inline void dma_buf_put(struct dma_buf *dmabuf)
>> return;
>> }
>>
>> +static inline unsigned int dma_buf_max_seg_size(struct dma_buf *dmabuf)
>> +{
>> + return 0;
>> +}
>> +
>> +static inline unsigned int dma_buf_max_seg_count(struct dma_buf *dmabuf)
>> +{
>> + return 0;
>> +}
>> +
>> +static inline unsigned int dma_buf_get_seg_boundary(struct dma_buf *dmabuf)
>> +{
>> + return 0;
>> +}
>> +
>> static inline struct sg_table *dma_buf_map_attachment(
>> struct dma_buf_attachment *attach, enum dma_data_direction write)
>> {
>> --
>> 1.7.9.5
>>
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Re: [PATCH 2/2] dma-buf: add helpers for attacher dma-parms [ In reply to ]

t.stanislaws at samsung

Aug 6, 2012, 3:29 AM

Post #4 of 6 (185 views)

Permalink

Hi Rob,

On 07/19/2012 06:23 PM, Rob Clark wrote:
> From: Rob Clark <rob@ti.com>
>
> Add some helpers to iterate through all attachers and get the most
> restrictive segment size/count/boundary.
>
> Signed-off-by: Rob Clark <rob@ti.com>
> ---
> drivers/base/dma-buf.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/dma-buf.h | 19 ++++++++++++++
> 2 files changed, 82 insertions(+)
>
> diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
> index 24e88fe..757ee20 100644
> --- a/drivers/base/dma-buf.c
> +++ b/drivers/base/dma-buf.c
> @@ -192,6 +192,69 @@ void dma_buf_put(struct dma_buf *dmabuf)
> EXPORT_SYMBOL_GPL(dma_buf_put);
>
> /**
> + * dma_buf_max_seg_size - helper for exporters to get the minimum of
> + * all attached device's max segment size
> + */
> +unsigned int dma_buf_max_seg_size(struct dma_buf *dmabuf)
> +{
> + struct dma_buf_attachment *attach;
> + unsigned int max = (unsigned int)-1;
> +
> + if (WARN_ON(!dmabuf))
> + return 0;

Maybe you should change return type to 'int' and return -EINVAL here?

> +
> + mutex_lock(&dmabuf->lock);
> + list_for_each_entry(attach, &dmabuf->attachments, node)
> + max = min(max, dma_get_max_seg_size(attach->dev));
> + mutex_unlock(&dmabuf->lock);
> +
> + return max;
> +}
> +EXPORT_SYMBOL_GPL(dma_buf_max_seg_size);
> +
> +/**
> + * dma_buf_max_seg_count - helper for exporters to get the minimum of
> + * all attached device's max segment count
> + */
> +unsigned int dma_buf_max_seg_count(struct dma_buf *dmabuf)
> +{
> + struct dma_buf_attachment *attach;
> + unsigned int max = (unsigned int)-1;
> +
> + if (WARN_ON(!dmabuf))
> + return 0;

maybe return -EINVAL here?

> +
> + mutex_lock(&dmabuf->lock);
> + list_for_each_entry(attach, &dmabuf->attachments, node)
> + max = min(max, dma_get_max_seg_count(attach->dev));

I think that there is a bug here.
Assume that there are two deices on the list, one using unlimited number of
segments (value 0), the second one needs a contiguous buffer (value 1).
The result of the function is 0 = min(0, 2).

The return value 0 indicates that the unlimited number of sg segments is
accepted what is *wrong* because the correct value should be 1.

I recommend to change the semantics for unlimited number of segments
from 'value 0' to:

#define DMA_SEGMENTS_COUNT_UNLIMITED ((unsigned long)INT_MAX)

Using INT_MAX will allow using safe conversions between signed and
unsigned integers.

> + mutex_unlock(&dmabuf->lock);
> +
> + return max;
> +}
> +EXPORT_SYMBOL_GPL(dma_buf_max_seg_count);
> +
> +/**
> + * dma_buf_get_seg_boundary - helper for exporters to get the most
> + * restrictive segment alignment of all the attached devices
> + */
> +unsigned int dma_buf_get_seg_boundary(struct dma_buf *dmabuf)
> +{
> + struct dma_buf_attachment *attach;
> + unsigned int mask = (unsigned int)-1;
> +
> + if (WARN_ON(!dmabuf))
> + return 0;
> +
> + mutex_lock(&dmabuf->lock);
> + list_for_each_entry(attach, &dmabuf->attachments, node)
> + mask &= dma_get_seg_boundary(attach->dev);
> + mutex_unlock(&dmabuf->lock);
> +
> + return mask;
> +}
> +EXPORT_SYMBOL_GPL(dma_buf_get_seg_boundary);
> +
> +/**
> * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
> * calls attach() of dma_buf_ops to allow device-specific attach functionality
> * @dmabuf: [in] buffer to attach device to.
> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
> index eb48f38..9533b9b 100644
> --- a/include/linux/dma-buf.h
> +++ b/include/linux/dma-buf.h
> @@ -167,6 +167,10 @@ int dma_buf_fd(struct dma_buf *dmabuf, int flags);
> struct dma_buf *dma_buf_get(int fd);
> void dma_buf_put(struct dma_buf *dmabuf);
>
> +unsigned int dma_buf_max_seg_size(struct dma_buf *dmabuf);
> +unsigned int dma_buf_max_seg_count(struct dma_buf *dmabuf);
> +unsigned int dma_buf_get_seg_boundary(struct dma_buf *dmabuf);

Instead of adding an army of new handlers you could provide a single helper:

int dma_buf_get_parameters(struct dma_buf *dmabuf,
struct device_dma_parameters *params);

This function will fill *params with lowest common DMA requirements for
all devices on attachment list. Return value can be used to diagnose
errors like incorrectly initialized dma_buf pointer
(like no attachments on an attachment list).

Moreover, there will be no need to add a new handler every time
device_dma_parameters is extended.

Regards,
Tomasz Stanislawski

> +
> struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
> enum dma_data_direction);
> void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
> @@ -220,6 +224,21 @@ static inline void dma_buf_put(struct dma_buf *dmabuf)
> return;
> }
>
> +static inline unsigned int dma_buf_max_seg_size(struct dma_buf *dmabuf)
> +{
> + return 0;
> +}
> +
> +static inline unsigned int dma_buf_max_seg_count(struct dma_buf *dmabuf)
> +{
> + return 0;
> +}
> +
> +static inline unsigned int dma_buf_get_seg_boundary(struct dma_buf *dmabuf)
> +{
> + return 0;
> +}
> +
> static inline struct sg_table *dma_buf_map_attachment(
> struct dma_buf_attachment *attach, enum dma_data_direction write)
> {
>

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Re: [PATCH 2/2] dma-buf: add helpers for attacher dma-parms [ In reply to ]

mina86 at mina86

Aug 6, 2012, 4:58 AM

Post #5 of 6 (190 views)

Permalink

Tomasz Stanislawski <t.stanislaws@samsung.com> writes:
> I recommend to change the semantics for unlimited number of segments
> from 'value 0' to:
>
> #define DMA_SEGMENTS_COUNT_UNLIMITED ((unsigned long)INT_MAX)
>
> Using INT_MAX will allow using safe conversions between signed and
> unsigned integers.

LONG_MAX seems cleaner regardless.

--
Best regards, _ _
.o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o
..o | Computer Science, MichaÅ‚ â€œmina86â€ Nazarewicz (o o)
ooo +----<email/xmpp: mpn@google.com>--------------ooO--(_)--Ooo--

Re: [PATCH 2/2] dma-buf: add helpers for attacher dma-parms [ In reply to ]

t.stanislaws at samsung

Aug 6, 2012, 5:42 AM

Post #6 of 6 (185 views)

Permalink

On 08/06/2012 01:58 PM, Michal Nazarewicz wrote:
>
> Tomasz Stanislawski <t.stanislaws@samsung.com> writes:
>> I recommend to change the semantics for unlimited number of segments
>> from 'value 0' to:
>>
>> #define DMA_SEGMENTS_COUNT_UNLIMITED ((unsigned long)INT_MAX)

Sorry. It should be:
#define DMA_SEGMENTS_COUNT_UNLIMITED ((unsigned int)INT_MAX)

>>
>> Using INT_MAX will allow using safe conversions between signed and
>> unsigned integers.
>
> LONG_MAX seems cleaner regardless.
>
>
>

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