Re: [PATCH 0/2] i2c: i801: Detect SPD Write Disable and expose as adapter quirk

[TINSAE TADESSE]

On Thu, Feb 5, 2026 at 1:29 PM Tinsae Tadesse
<tinsaetadesse2015@xxxxxxxxx> wrote:
>
> Hi I2C and HWMON maintainers,
>
> Intel i801 SMBus controllers feature a "SPD Write Disable" bit
> in the SMBHSTCFG register. When set by firmware, the hardware
> silently blocks all write transactions to the SPD EEPROM
> address range (0x50-0x57) while allowing reads to succeed.
>
> This creates a significant issue for the spd5118 hwmon driver.
> The SPD5118 requires write access for switching between
> register pages to read temperature data, and for cache
> synchronization during suspend/resume. When SPD Write Disable
> is set and the spd5118 driver attempts write transactions, the
> bus will generate a storm of SMBus DEV_ERR messages.
>
> This patch series proposes a generic solution by:
> 1. Introducing a new adapter quirk flag in include/linux/i2c.h
> to communicate this hardware restriction.
> 2. Modifying drivers/i2c/i2c-i801.c to detect the SPD Write
> Disable bit and set the quirk flag.
> 3. Modifying drivers/hwmon/spd5118.c to check for this quirk
> during probe and fail cleanly, as write access is mandatory.
>
> By using this mechanism, we avoid embedding device-specific
> policies in the controller driver and provide client drivers
> with the necessary information to make an informed decision.
>
> Tinsae Tadesse (2):
>   i2c: i801: Detect SPD Write Disable and expose as adapter quirk
>   hwmon: spd5118: Fail probe if SPD writes are disabled
>
>  drivers/hwmon/spd5118.c       | 15 +++++++++++++++
>  drivers/i2c/busses/i2c-i801.c | 16 +++++++++++++++-
>  include/linux/i2c.h           |  3 +++
>  3 files changed, 33 insertions(+), 1 deletion(-)
>
> --
> 2.52.0
>


Hi Wolfram, Jean, and Andi;

Please review this patch series.

Thanks,
Tinsae Tadesse