| Message ID | 20250227222455.2583468-1-titusr@google.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | hwmon: (pmbus) Initialise page count in pmbus_identify() | expand |
On Thu, Feb 27, 2025 at 10:24:55PM +0000, Titus Rwantare wrote: > 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 <titusr@google.com> Applied. Thanks, Guenter
diff --git a/drivers/hwmon/pmbus/pmbus.c b/drivers/hwmon/pmbus/pmbus.c index 77cf268e7d2d..920cd5408141 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;
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 <titusr@google.com> --- drivers/hwmon/pmbus/pmbus.c | 2 ++ 1 file changed, 2 insertions(+)