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| author | Titus Rwantare <titusr@google.com> | 2025-02-27 22:24:55 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-03-13 12:53:16 +0100 |
| commit | afaf7f45161860dd0f29ccd3a790860da36f0724 (patch) | |
| tree | 78a4a75f6ea2ceb9b38398c06bcf470974d8dd80 /drivers/hwmon | |
| parent | 29e0cd296c87240278e2f7ea4cf3f496b60c03af (diff) | |
| download | linux-afaf7f45161860dd0f29ccd3a790860da36f0724.tar.gz linux-afaf7f45161860dd0f29ccd3a790860da36f0724.tar.bz2 linux-afaf7f45161860dd0f29ccd3a790860da36f0724.zip | |
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 <titusr@google.com>
Fixes: 442aba78728e7 ("hwmon: PMBus device driver")
Link: https://lore.kernel.org/r/20250227222455.2583468-1-titusr@google.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/hwmon')
| -rw-r--r-- | drivers/hwmon/pmbus/pmbus.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/hwmon/pmbus/pmbus.c b/drivers/hwmon/pmbus/pmbus.c index d0d386990af5..6366610a9082 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; |