hwmon: (pmbus) Initialise page count in pmbus_identify()

The pmbus_identify() function fails to correctly determine the number of supported pages on PMBus devices. This occurs because info->pages is implicitly zero-initialised, and pmbus_set_page() does not perform writes to the page register if info->pages is not yet initialised. Without this patch, info->pages is always set to the maximum after scanning.

This patch initialises info->pages to PMBUS_PAGES before the probing loop, enabling pmbus_set_page() writes to make it out onto the bus correctly identifying the number of pages. PMBUS_PAGES seemed like a reasonable non-zero number because that's the current result of the identification process.

Testing was done with a PMBus device in QEMU.

---
 drivers/hwmon/pmbus/pmbus.c | 2 ++
 1 file changed, 2 insertions(+)

index 77cf268e7d2d..920cd5408141 100644
@@ -103,6 +103,8 @@ static int pmbus_identify(struct i2c_client *client,
 		if (pmbus_check_byte_register(client, 0, PMBUS_PAGE)) {
 			int page;
 
+			info->pages = PMBUS_PAGES;
+
 			for (page = 1; page < PMBUS_PAGES; page++) {
 				if (pmbus_set_page(client, page, 0xff) < 0)
 					break;

2.48.1.711.g2feabab25a-goog

Applied.

Thanks,
Guenter