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SubjectRe: [PATCH v1 7/7] ACPI: property: Allow counting a single value as an array of 1 element
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On Wednesday, February 10, 2021 1:36:00 PM CET Rafael J. Wysocki wrote:
> On Wed, Feb 10, 2021 at 12:51 PM Andy Shevchenko
> <andriy.shevchenko@linux.intel.com> wrote:
> >
> > We allow to read the single value as a first element in the array.
> > Unfortunately the counting doesn't work in this case and we can't
> > call fwnode_property_count_*() API without getting an error.
>
> It would be good to mention what the symptom of the issue is here.
>
> > Modify acpi_data_prop_read() to always try the single value read
> > and thus allow counting the single value as an array of 1 element.
> >
> > Reported-by: Calvin Johnson <calvin.johnson@oss.nxp.com>
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
>
> This is a bug fix, so it should go in before the cleanups in this series IMO.
>
> Also it looks like stable@vger material.
>
> > ---
> > drivers/acpi/property.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
> > index 236316ee0e25..d6100585fceb 100644
> > --- a/drivers/acpi/property.c
> > +++ b/drivers/acpi/property.c
> > @@ -913,12 +913,14 @@ static int acpi_data_prop_read(const struct acpi_device_data *data,
> > const union acpi_object *items;
> > int ret;
> >
> > - if (val && nval == 1) {
> > + /* Try to read as a single value first */
> > + if (!val || nval == 1) {
> > ret = acpi_data_prop_read_single(data, propname, proptype, val);
>
> This returns -EINVAL if val is NULL.
>
> > if (ret >= 0)
> > - return ret;
> > + return val ? ret : 1;
>
> So val cannot be NULL here.
>
> > }
> >
> > + /* It's not the single value, get an array instead */
> > ret = acpi_data_get_property_array(data, propname, ACPI_TYPE_ANY, &obj);
> > if (ret)
> > return ret;
> > --
>
> To me, acpi_fwnode_property_read_string_array() needs to special-case
> val == NULL and nval == 0.

Well, scratch this.

Something like the patch below (untested) should be sufficient to address this
if I'm not mistaken.

---
drivers/acpi/property.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)

Index: linux-pm/drivers/acpi/property.c
===================================================================
--- linux-pm.orig/drivers/acpi/property.c
+++ linux-pm/drivers/acpi/property.c
@@ -787,14 +787,14 @@ static int acpi_data_prop_read_single(co
const union acpi_object *obj;
int ret;

- if (!val)
- return -EINVAL;
-
if (proptype >= DEV_PROP_U8 && proptype <= DEV_PROP_U64) {
ret = acpi_data_get_property(data, propname, ACPI_TYPE_INTEGER, &obj);
if (ret)
return ret;

+ if (!val)
+ return 1;
+
switch (proptype) {
case DEV_PROP_U8:
if (obj->integer.value > U8_MAX)
@@ -820,7 +820,8 @@ static int acpi_data_prop_read_single(co
if (ret)
return ret;

- *(char **)val = obj->string.pointer;
+ if (val)
+ *(char **)val = obj->string.pointer;

return 1;
} else {
@@ -928,10 +929,16 @@ static int acpi_data_prop_read(const str
const union acpi_object *items;
int ret;

- if (val && nval == 1) {
+ if (nval == 1) {
ret = acpi_data_prop_read_single(data, propname, proptype, val);
if (ret >= 0)
return ret;
+
+ /*
+ * Reading this property as a single-value one failed, but its
+ * value may still be represented as one-element array, so
+ * continue.
+ */
}

ret = acpi_data_get_property_array(data, propname, ACPI_TYPE_ANY, &obj);



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