From: Titus Rwantare Date: Thu, 27 Feb 2025 22:24:55 +0000 (+0000) Subject: hwmon: (pmbus) Initialise page count in pmbus_identify() X-Git-Tag: v5.10.235~52 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=bababb694461d63b48719bf3da250cb82aa5daed;p=thirdparty%2Fkernel%2Fstable.git hwmon: (pmbus) Initialise page count in pmbus_identify() [ Upstream commit 6b6e2e8fd0de3fa7c6f4f8fe6841b01770b2e7bc ] 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. Signed-off-by: Titus Rwantare Fixes: 442aba78728e7 ("hwmon: PMBus device driver") Link: https://lore.kernel.org/r/20250227222455.2583468-1-titusr@google.com Signed-off-by: Guenter Roeck Signed-off-by: Sasha Levin --- diff --git a/drivers/hwmon/pmbus/pmbus.c b/drivers/hwmon/pmbus/pmbus.c index 20f1af9165c2d..2bfccbfbc2896 100644 --- a/drivers/hwmon/pmbus/pmbus.c +++ b/drivers/hwmon/pmbus/pmbus.c @@ -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;