Re: [PATCH -next v2 1/2] device property: Return -ENXIO if there is no suitable FW interface

On Wednesday, August 26, 2015 04:25:59 PM Guenter Roeck wrote:

On 08/26/2015 04:37 PM, Rafael J. Wysocki wrote:

quoted

On Wednesday, August 26, 2015 01:20:44 PM Guenter Roeck wrote:

quoted

Return -ENXIO if device property array access functions don't find
a suitable firmware interface.

This lets drivers decide if they should use available platform data
instead.

Cc: Rafael J. Wysocki <redacted>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v2: Added patch

  drivers/base/property.c | 7 +++++++
  1 file changed, 7 insertions(+)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index 287704d680bf..9600b824d138 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c

@@ -69,6 +69,9 @@ static int pset_prop_read_array(struct property_set *pset, const char *name,
  	struct property_entry *prop;
  	unsigned int item_size;

+	if (!pset)
+		return -ENXIO;
+

This isn't exactly straightforward, because it relies on the fact that
pset_prop_read_array() is the last thing tried by FWNODE_PROP_READ_ARRAY()
and fwnode_property_read_string_array().  A comment about that might be
helpful.

I see two options: Add a comment above, or change the calling code to

	...
	else if (is_pset(fwnode))
		return pset_prop_read_array(to_pset(fwnode), propname,
                          	            DEV_PROP_STRING, val, nval);
	return -ENXIO;

which would make it obvious and avoid side effects if the code is changed
later on. Would you be ok with this ?

The second option is obviously cleaner to me and I prefer cleaner code. :-)

Thanks,
Rafael