Re: [PATCH] hwmon: (nct6694) do not expose enable on DTIN temperature channels

[Guenter Roeck <linux@roeck-us.net>]

On Mon, Aug 03, 2026 at 10:21:48AM +0000, Ali Ahmet Memis wrote:
> The driver registers 26 temperature channels, all advertising
> HWMON_T_ENABLE, and indexes the enable bitmap with the raw channel:
> 
> 	data->hwmon_en.tin_en[channel / 8] |= BIT(channel % 8);
> 
> tin_en is two bytes and only covers the 5 THR and 5 TDP channels
> (index 0-9). The 16 DTIN channels (index 10-25) are enabled by the
> firmware and were never meant to carry an enable bit. Because the
> control structure is packed, writing temp17_enable and above indexes
> past tin_en into the fin_en bytes that follow it, so it toggles fan
> enable state instead; nct6694_hwmon_init() then sends the whole
> structure back to the device, and reads report fan state as temperature
> state. It stays within the structure, so this is not a memory safety
> problem, but on a board that uses the fan channels it is not harmless.
> 
> Give the DTIN channels a temperature config without HWMON_T_ENABLE so
> the core never creates their enable attribute. The enable path is then
> reachable only for the first 10 channels, which stay within tin_en, and
> fin_en is left alone. The DTIN input and limit attributes are unchanged.
> 
> Fixes: 197e779d29d8 ("hwmon: Add Nuvoton NCT6694 HWMON support")
> Suggested-by: Ming Yu <tmyu0@nuvoton.com>
> Link: https://lore.kernel.org/all/20260802124730.20387-1-ali@iusegentoo.com/
> Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>

Applied.

Thanks,
Guenter