The max9611 driver tests communications with the chip by reading the die temperature during the probe function. If the temperature register POR (power-on reset) value is returned from the test read, defer probe to give the chip a bit more time to properly exit from reset.
Reported-by: Geert Uytterhoeven <[email protected]> Signed-off-by: Jacopo Mondi <[email protected]> --- Geert, I've not been able to reproduce the issue on my boards (M3-N Salvator-XS and M3-W Salvator-X). As you reported the issue you might be able to reproduce it, could you please test this? Also, I opted for deferring probe instead of arbitrary repeat the temperature read. What's your opinion? Thanks j --- drivers/iio/adc/max9611.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/iio/adc/max9611.c b/drivers/iio/adc/max9611.c index da073d72f649..30ae5879252c 100644 --- a/drivers/iio/adc/max9611.c +++ b/drivers/iio/adc/max9611.c @@ -80,6 +80,7 @@ * The complete formula to calculate temperature is: * ((adc_read >> 7) * 1000) / (1 / 480 * 1000) */ +#define MAX9611_TEMP_POR 0x8000 #define MAX9611_TEMP_MAX_POS 0x7f80 #define MAX9611_TEMP_MAX_NEG 0xff80 #define MAX9611_TEMP_MIN_NEG 0xd980 @@ -480,8 +481,10 @@ static int max9611_init(struct max9611_dev *max9611) if (ret) return ret; - regval &= MAX9611_TEMP_MASK; + if (regval == MAX9611_TEMP_POR) + return -EPROBE_DEFER; + regval &= MAX9611_TEMP_MASK; if ((regval > MAX9611_TEMP_MAX_POS && regval < MAX9611_TEMP_MIN_NEG) || regval > MAX9611_TEMP_MAX_NEG) { -- 2.23.0
