Messages in this thread Patch in this message | | | Subject | Re: [PATCH 1/7] of: base: Add of_count_phandle_with_fixed_args() | From | Robin Murphy <> | Date | Thu, 15 Oct 2020 17:52:35 +0100 |
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On 2020-10-14 19:39, Rob Herring wrote: > On Wed, Oct 14, 2020 at 9:54 AM Richard Fitzgerald > <rf@opensource.cirrus.com> 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 <rf@opensource.cirrus.com> >> --- >> 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, &size); >> + 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(&it, np, list_name, NULL, cells_count); >> + if (rc) >> + return rc; >> + >> + while ((rc = of_phandle_iterator_next(&it)) == 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 >> > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >
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