Re: [PATCH 1/2] hw/misc/tmp105: reset the T_low and T_High registers

[Cédric Le Goater]

On 11/10/20 4:00 PM, Peter Maydell wrote:
> The TMP105 datasheet (https://www.ti.com/lit/gpn/tmp105) says that the
> power-up reset values for the T_low and T_high registers are 80 degrees C
> and 75 degrees C, which are 0x500 and 0x4B0 hex according to table 5.  These
> values are then shifted right by four bits to give the register reset
> values, since both registers store the 12 bits of temperature data in bits
> [15..4] of a 16 bit register.
> 
> We were resetting these registers to zero, which is problematic for Linux
> guests which enable the alert interrupt and then immediately take an
> unexpected overtemperature alert because the current temperature is above
> freezing...
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Cédric Le Goater <clg@kaod.org>



> ---
>  hw/misc/tmp105.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/hw/misc/tmp105.c b/hw/misc/tmp105.c
> index b47120492a..0a4aad4854 100644
> --- a/hw/misc/tmp105.c
> +++ b/hw/misc/tmp105.c
> @@ -225,6 +225,9 @@ static void tmp105_reset(I2CSlave *i2c)
>      s->faults = tmp105_faultq[(s->config >> 3) & 3];
>      s->alarm = 0;
> 
> +    s->limit[0] = 0x4b00; /* T_LOW, 75 degrees C */
> +    s->limit[1] = 0x5000; /* T_HIGH, 80 degrees C */
> +
>      tmp105_interrupt_update(s);
>  }
>