Re: [PATCH 1/7] of: base: Add of_count_phandle_with_fixed_args()
On 16/10/2020 14:31, Rob Herring wrote:
On Thu, Oct 15, 2020 at 11:52 AM Robin Murphy wrote:
On 2020-10-14 19:39, Rob Herring wrote:
On Wed, Oct 14, 2020 at 9:54 AM Richard Fitzgerald
wrote:
Add an equivalent of of_count_phandle_with_args() for fixed argument
sets, to pair with of_parse_phandle_with_fixed_args().
Signed-off-by: Richard Fitzgerald
---
drivers/of/base.c | 42 ++
include/linux/of.h | 9 +
2 files changed, 51 insertions(+)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index ea44fea99813..45d8b0e65345 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1772,6 +1772,48 @@ int of_count_phandle_with_args(const struct device_node
*np, const char *list_na
}
EXPORT_SYMBOL(of_count_phandle_with_args);
+/**
+ * of_count_phandle_with_fixed_args() - Find the number of phandles references
in a property
+ * @np:pointer to a device tree node containing a list
+ * @list_name: property name that contains a list
+ * @cell_count: number of argument cells following the phandle
+ *
+ * Returns the number of phandle + argument tuples within a property. It
+ * is a typical pattern to encode a list of phandle and variable
+ * arguments into a single property.
+ */
+int of_count_phandle_with_fixed_args(const struct device_node *np,
+const char *list_name,
+int cells_count)
+{
Looks to me like you can refactor of_count_phandle_with_args to handle
both case and then make this and of_count_phandle_with_args simple
wrapper functions.
Although for just counting the number of phandles each with n arguments
that a property contains, isn't that simply a case of dividing the
property length by n + 1? The phandles themselves will be validated by
any subsequent of_parse_phandle*() call anyway, so there doesn't seem
much point in doing more work then necessary here.
+ struct of_phandle_iterator it;
+ int rc, cur_index = 0;
+
+ if (!cells_count) {
+ const __be32 *list;
+ int size;
+
+ list = of_get_property(np, list_name, );
+ if (!list)
+ return -ENOENT;
+
+ return size / sizeof(*list);
Case in point - if it's OK to do exactly that for n == 0, then clearly
we're *aren't* fussed about validating anything, so the n > 0 code below
is nothing more than a massively expensive way to check for a nonzero
remainder :/
Indeed. We should just generalize this. It can still be refactored to
shared code.
It's probably worthwhile to check for a remainder here IMO.
Ok, I looked at the implementation of of_phandle_iterator_next() and
it is in fact simply incrementing by 'count' 32-bit words. So as Robin
said the count_phandle_with_x_args()functions could simply divide the
length by count+1.
However, may I suggest that should be done in a separate patch after my
patch to add count_phandle_with_fixed_args()? That way, if replacing the
iteration with the simple length divide causes any unforeseen problems
the patch can just be reverted.
Rob
Re: [PATCH 1/7] of: base: Add of_count_phandle_with_fixed_args()
On Thu, Oct 15, 2020 at 11:52 AM Robin Murphy wrote:
>
> On 2020-10-14 19:39, Rob Herring wrote:
> > On Wed, Oct 14, 2020 at 9:54 AM Richard Fitzgerald
> > wrote:
> >>
> >> Add an equivalent of of_count_phandle_with_args() for fixed argument
> >> sets, to pair with of_parse_phandle_with_fixed_args().
> >>
> >> Signed-off-by: Richard Fitzgerald
> >> ---
> >> drivers/of/base.c | 42 ++
> >> include/linux/of.h | 9 +
> >> 2 files changed, 51 insertions(+)
> >>
> >> diff --git a/drivers/of/base.c b/drivers/of/base.c
> >> index ea44fea99813..45d8b0e65345 100644
> >> --- a/drivers/of/base.c
> >> +++ b/drivers/of/base.c
> >> @@ -1772,6 +1772,48 @@ int of_count_phandle_with_args(const struct
> >> device_node *np, const char *list_na
> >> }
> >> EXPORT_SYMBOL(of_count_phandle_with_args);
> >>
> >> +/**
> >> + * of_count_phandle_with_fixed_args() - Find the number of phandles
> >> references in a property
> >> + * @np:pointer to a device tree node containing a list
> >> + * @list_name: property name that contains a list
> >> + * @cell_count: number of argument cells following the phandle
> >> + *
> >> + * Returns the number of phandle + argument tuples within a property. It
> >> + * is a typical pattern to encode a list of phandle and variable
> >> + * arguments into a single property.
> >> + */
> >> +int of_count_phandle_with_fixed_args(const struct device_node *np,
> >> +const char *list_name,
> >> +int cells_count)
> >> +{
> >
> > Looks to me like you can refactor of_count_phandle_with_args to handle
> > both case and then make this and of_count_phandle_with_args simple
> > wrapper functions.
>
> Although for just counting the number of phandles each with n arguments
> that a property contains, isn't that simply a case of dividing the
> property length by n + 1? The phandles themselves will be validated by
> any subsequent of_parse_phandle*() call anyway, so there doesn't seem
> much point in doing more work then necessary here.
>
> >> + struct of_phandle_iterator it;
> >> + int rc, cur_index = 0;
> >> +
> >> + if (!cells_count) {
> >> + const __be32 *list;
> >> + int size;
> >> +
> >> + list = of_get_property(np, list_name, );
> >> + if (!list)
> >> + return -ENOENT;
> >> +
> >> + return size / sizeof(*list);
>
> Case in point - if it's OK to do exactly that for n == 0, then clearly
> we're *aren't* fussed about validating anything, so the n > 0 code below
> is nothing more than a massively expensive way to check for a nonzero
> remainder :/
Indeed. We should just generalize this. It can still be refactored to
shared code.
It's probably worthwhile to check for a remainder here IMO.
Rob
Re: [PATCH 1/7] of: base: Add of_count_phandle_with_fixed_args()
On 15/10/2020 17:52, Robin Murphy wrote:
On 2020-10-14 19:39, Rob Herring wrote:
On Wed, Oct 14, 2020 at 9:54 AM Richard Fitzgerald
wrote:
Add an equivalent of of_count_phandle_with_args() for fixed argument
sets, to pair with of_parse_phandle_with_fixed_args().
Signed-off-by: Richard Fitzgerald
---
drivers/of/base.c | 42 ++
include/linux/of.h | 9 +
2 files changed, 51 insertions(+)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index ea44fea99813..45d8b0e65345 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1772,6 +1772,48 @@ int of_count_phandle_with_args(const struct
device_node *np, const char *list_na
}
EXPORT_SYMBOL(of_count_phandle_with_args);
+/**
+ * of_count_phandle_with_fixed_args() - Find the number of phandles
references in a property
+ * @np: pointer to a device tree node containing a list
+ * @list_name: property name that contains a list
+ * @cell_count: number of argument cells following the phandle
+ *
+ * Returns the number of phandle + argument tuples within a
property. It
+ * is a typical pattern to encode a list of phandle and variable
+ * arguments into a single property.
+ */
+int of_count_phandle_with_fixed_args(const struct device_node *np,
+ const char *list_name,
+ int cells_count)
+{
Looks to me like you can refactor of_count_phandle_with_args to handle
both case and then make this and of_count_phandle_with_args simple
wrapper functions.
Although for just counting the number of phandles each with n arguments
that a property contains, isn't that simply a case of dividing the
property length by n + 1? The phandles themselves will be validated by
any subsequent of_parse_phandle*() call anyway, so there doesn't seem
much point in doing more work then necessary here.
As I'm not a DT expert, I'm reluctant to change existing algorithms that
could break everything just for the trivial case of adding a fixed
arguments count. I have a re-worked patch as suggested by Rob that
re-uses the existing counting function for both cases.
+ struct of_phandle_iterator it;
+ int rc, cur_index = 0;
+
+ if (!cells_count) {
+ const __be32 *list;
+ int size;
+
+ list = of_get_property(np, list_name, );
+ if (!list)
+ return -ENOENT;
+
+ return size / sizeof(*list);
Case in point - if it's OK to do exactly that for n == 0, then clearly
we're *aren't* fussed about validating anything, so the n > 0 code below
is nothing more than a massively expensive way to check for a nonzero
remainder :/
Robin.
+ }
+
+ rc = of_phandle_iterator_init(, np, list_name, NULL,
cells_count);
+ if (rc)
+ return rc;
+
+ while ((rc = of_phandle_iterator_next()) == 0)
+ cur_index += 1;
+
+ if (rc != -ENOENT)
+ return rc;
+
+ return cur_index;
+}
+EXPORT_SYMBOL(of_count_phandle_with_fixed_args);
+
/**
* __of_add_property - Add a property to a node without lock
operations
*/
diff --git a/include/linux/of.h b/include/linux/of.h
index 5cf7ae0465d1..9f315da4e9da 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -377,6 +377,8 @@ extern int of_parse_phandle_with_fixed_args(const
struct device_node *np,
struct of_phandle_args *out_args);
extern int of_count_phandle_with_args(const struct device_node *np,
const char *list_name, const char *cells_name);
+extern int of_count_phandle_with_fixed_args(const struct device_node
*np,
+ const char *list_name, int cells_count);
/* phandle iterator functions */
extern int of_phandle_iterator_init(struct of_phandle_iterator *it,
@@ -886,6 +888,13 @@ static inline int
of_count_phandle_with_args(struct device_node *np,
return -ENOSYS;
}
+static inline int of_count_phandle_with_fixed_args(const struct
device_node *np,
+ const char
*list_name,
+ int cells_count)
+{
+ return -ENOSYS;
+}
+
static inline int of_phandle_iterator_init(struct
of_phandle_iterator *it,
const struct device_node
*np,
const char *list_name,
--
2.20.1
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Re: [PATCH 1/7] of: base: Add of_count_phandle_with_fixed_args()
On 2020-10-14 19:39, Rob Herring wrote:
On Wed, Oct 14, 2020 at 9:54 AM Richard Fitzgerald
wrote:
Add an equivalent of of_count_phandle_with_args() for fixed argument
sets, to pair with of_parse_phandle_with_fixed_args().
Signed-off-by: Richard Fitzgerald
---
drivers/of/base.c | 42 ++
include/linux/of.h | 9 +
2 files changed, 51 insertions(+)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index ea44fea99813..45d8b0e65345 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1772,6 +1772,48 @@ int of_count_phandle_with_args(const struct device_node
*np, const char *list_na
}
EXPORT_SYMBOL(of_count_phandle_with_args);
+/**
+ * of_count_phandle_with_fixed_args() - Find the number of phandles references
in a property
+ * @np:pointer to a device tree node containing a list
+ * @list_name: property name that contains a list
+ * @cell_count: number of argument cells following the phandle
+ *
+ * Returns the number of phandle + argument tuples within a property. It
+ * is a typical pattern to encode a list of phandle and variable
+ * arguments into a single property.
+ */
+int of_count_phandle_with_fixed_args(const struct device_node *np,
+const char *list_name,
+int cells_count)
+{
Looks to me like you can refactor of_count_phandle_with_args to handle
both case and then make this and of_count_phandle_with_args simple
wrapper functions.
Although for just counting the number of phandles each with n arguments
that a property contains, isn't that simply a case of dividing the
property length by n + 1? The phandles themselves will be validated by
any subsequent of_parse_phandle*() call anyway, so there doesn't seem
much point in doing more work then necessary here.
+ struct of_phandle_iterator it;
+ int rc, cur_index = 0;
+
+ if (!cells_count) {
+ const __be32 *list;
+ int size;
+
+ list = of_get_property(np, list_name, );
+ if (!list)
+ return -ENOENT;
+
+ return size / sizeof(*list);
Case in point - if it's OK to do exactly that for n == 0, then clearly
we're *aren't* fussed about validating anything, so the n > 0 code below
is nothing more than a massively expensive way to check for a nonzero
remainder :/
Robin.
+ }
+
+ rc = of_phandle_iterator_init(, np, list_name, NULL, cells_count);
+ if (rc)
+ return rc;
+
+ while ((rc = of_phandle_iterator_next()) == 0)
+ cur_index += 1;
+
+ if (rc != -ENOENT)
+ return rc;
+
+ return cur_index;
+}
+EXPORT_SYMBOL(of_count_phandle_with_fixed_args);
+
/**
* __of_add_property - Add a property to a node without lock operations
*/
diff --git a/include/linux/of.h b/include/linux/of.h
index 5cf7ae0465d1..9f315da4e9da 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -377,6 +377,8 @@ extern int of_parse_phandle_with_fixed_args(const struct
device_node *np,
struct of_phandle_args *out_args);
extern int of_count_phandle_with_args(const struct device_node *np,
const char *list_name, const char *cells_name);
+extern int of_count_phandle_with_fixed_args(const struct device_node *np,
+ const char *list_name, int cells_count);
/* phandle iterator functions */
extern int of_phandle_iterator_init(struct of_phandle_iterator *it,
@@ -886,6 +888,13 @@ static inline int of_count_phandle_with_args(struct
device_node *np,
return -ENOSYS;
}
+static inline int of_count_phandle_with_fixed_args(const struct device_node
*np,
+ const char *list_name,
+ int cells_count)
+{
+ return -ENOSYS;
+}
+
static inline int of_phandle_iterator_init(struct of_phandle_iterator *it,
const struct device_node *np,
const char *list_name,
--
2.20.1
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Re: [PATCH 1/7] of: base: Add of_count_phandle_with_fixed_args()
On Wed, Oct 14, 2020 at 9:54 AM Richard Fitzgerald
wrote:
>
> Add an equivalent of of_count_phandle_with_args() for fixed argument
> sets, to pair with of_parse_phandle_with_fixed_args().
>
> Signed-off-by: Richard Fitzgerald
> ---
> drivers/of/base.c | 42 ++
> include/linux/of.h | 9 +
> 2 files changed, 51 insertions(+)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index ea44fea99813..45d8b0e65345 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -1772,6 +1772,48 @@ int of_count_phandle_with_args(const struct
> device_node *np, const char *list_na
> }
> EXPORT_SYMBOL(of_count_phandle_with_args);
>
> +/**
> + * of_count_phandle_with_fixed_args() - Find the number of phandles
> references in a property
> + * @np:pointer to a device tree node containing a list
> + * @list_name: property name that contains a list
> + * @cell_count: number of argument cells following the phandle
> + *
> + * Returns the number of phandle + argument tuples within a property. It
> + * is a typical pattern to encode a list of phandle and variable
> + * arguments into a single property.
> + */
> +int of_count_phandle_with_fixed_args(const struct device_node *np,
> +const char *list_name,
> +int cells_count)
> +{
Looks to me like you can refactor of_count_phandle_with_args to handle
both case and then make this and of_count_phandle_with_args simple
wrapper functions.
> + struct of_phandle_iterator it;
> + int rc, cur_index = 0;
> +
> + if (!cells_count) {
> + const __be32 *list;
> + int size;
> +
> + list = of_get_property(np, list_name, );
> + if (!list)
> + return -ENOENT;
> +
> + return size / sizeof(*list);
> + }
> +
> + rc = of_phandle_iterator_init(, np, list_name, NULL, cells_count);
> + if (rc)
> + return rc;
> +
> + while ((rc = of_phandle_iterator_next()) == 0)
> + cur_index += 1;
> +
> + if (rc != -ENOENT)
> + return rc;
> +
> + return cur_index;
> +}
> +EXPORT_SYMBOL(of_count_phandle_with_fixed_args);
> +
> /**
> * __of_add_property - Add a property to a node without lock operations
> */
> diff --git a/include/linux/of.h b/include/linux/of.h
> index 5cf7ae0465d1..9f315da4e9da 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -377,6 +377,8 @@ extern int of_parse_phandle_with_fixed_args(const struct
> device_node *np,
> struct of_phandle_args *out_args);
> extern int of_count_phandle_with_args(const struct device_node *np,
> const char *list_name, const char *cells_name);
> +extern int of_count_phandle_with_fixed_args(const struct device_node *np,
> + const char *list_name, int cells_count);
>
> /* phandle iterator functions */
> extern int of_phandle_iterator_init(struct of_phandle_iterator *it,
> @@ -886,6 +888,13 @@ static inline int of_count_phandle_with_args(struct
> device_node *np,
> return -ENOSYS;
> }
>
> +static inline int of_count_phandle_with_fixed_args(const struct device_node
> *np,
> + const char *list_name,
> + int cells_count)
> +{
> + return -ENOSYS;
> +}
> +
> static inline int of_phandle_iterator_init(struct of_phandle_iterator *it,
>const struct device_node *np,
>const char *list_name,
> --
> 2.20.1
>
[PATCH 1/7] of: base: Add of_count_phandle_with_fixed_args()
Add an equivalent of of_count_phandle_with_args() for fixed argument
sets, to pair with of_parse_phandle_with_fixed_args().
Signed-off-by: Richard Fitzgerald
---
drivers/of/base.c | 42 ++
include/linux/of.h | 9 +
2 files changed, 51 insertions(+)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index ea44fea99813..45d8b0e65345 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1772,6 +1772,48 @@ int of_count_phandle_with_args(const struct device_node
*np, const char *list_na
}
EXPORT_SYMBOL(of_count_phandle_with_args);
+/**
+ * of_count_phandle_with_fixed_args() - Find the number of phandles references
in a property
+ * @np:pointer to a device tree node containing a list
+ * @list_name: property name that contains a list
+ * @cell_count: number of argument cells following the phandle
+ *
+ * Returns the number of phandle + argument tuples within a property. It
+ * is a typical pattern to encode a list of phandle and variable
+ * arguments into a single property.
+ */
+int of_count_phandle_with_fixed_args(const struct device_node *np,
+const char *list_name,
+int cells_count)
+{
+ struct of_phandle_iterator it;
+ int rc, cur_index = 0;
+
+ if (!cells_count) {
+ const __be32 *list;
+ int size;
+
+ list = of_get_property(np, list_name, );
+ if (!list)
+ return -ENOENT;
+
+ return size / sizeof(*list);
+ }
+
+ rc = of_phandle_iterator_init(, np, list_name, NULL, cells_count);
+ if (rc)
+ return rc;
+
+ while ((rc = of_phandle_iterator_next()) == 0)
+ cur_index += 1;
+
+ if (rc != -ENOENT)
+ return rc;
+
+ return cur_index;
+}
+EXPORT_SYMBOL(of_count_phandle_with_fixed_args);
+
/**
* __of_add_property - Add a property to a node without lock operations
*/
diff --git a/include/linux/of.h b/include/linux/of.h
index 5cf7ae0465d1..9f315da4e9da 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -377,6 +377,8 @@ extern int of_parse_phandle_with_fixed_args(const struct
device_node *np,
struct of_phandle_args *out_args);
extern int of_count_phandle_with_args(const struct device_node *np,
const char *list_name, const char *cells_name);
+extern int of_count_phandle_with_fixed_args(const struct device_node *np,
+ const char *list_name, int cells_count);
/* phandle iterator functions */
extern int of_phandle_iterator_init(struct of_phandle_iterator *it,
@@ -886,6 +888,13 @@ static inline int of_count_phandle_with_args(struct
device_node *np,
return -ENOSYS;
}
+static inline int of_count_phandle_with_fixed_args(const struct device_node
*np,
+ const char *list_name,
+ int cells_count)
+{
+ return -ENOSYS;
+}
+
static inline int of_phandle_iterator_init(struct of_phandle_iterator *it,
const struct device_node *np,
const char *list_name,
--
2.20.1
