lkml.org 
[lkml]   [2021]   [Nov]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v2 1/2] hwmon: (sht4x) Fix EREMOTEIO errors
From
Date
On 11/20/21 12:40 PM, David Mosberger-Tang wrote:
> Per datasheet, SHT4x may need up to 8.2ms for a "high repeatability"
> measurement to complete. Attempting to read the result too early
> triggers a NAK which then causes an EREMOTEIO error.
>
> This behavior has been confirmed with a logic analyzer while running
> the I2C bus at only 40kHz. The low frequency precludes any
> signal-integrity issues, which was also confirmed by the absence of
> any CRC8 errors. In this configuration, a NAK occurred on any read
> that followed the measurement command within less than 8.2ms.
>
> Signed-off-by: David Mosberger-Tang <davidm@egauge.net>

You sent v2 after 5 minutes, and there is no change log.
Please never do that, and always provide a change log.

Guenter

> ---
> drivers/hwmon/sht4x.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hwmon/sht4x.c b/drivers/hwmon/sht4x.c
> index 09c2a0b06444..3415d7a0e0fc 100644
> --- a/drivers/hwmon/sht4x.c
> +++ b/drivers/hwmon/sht4x.c
> @@ -23,7 +23,7 @@
> /*
> * I2C command delays (in microseconds)
> */
> -#define SHT4X_MEAS_DELAY 1000
> +#define SHT4X_MEAS_DELAY_HPM 8200 /* see t_MEAS,h in datasheet */
> #define SHT4X_DELAY_EXTRA 10000
>
> /*
> @@ -90,7 +90,7 @@ static int sht4x_read_values(struct sht4x_data *data)
> if (ret < 0)
> goto unlock;
>
> - usleep_range(SHT4X_MEAS_DELAY, SHT4X_MEAS_DELAY + SHT4X_DELAY_EXTRA);
> + usleep_range(SHT4X_MEAS_DELAY_HPM, SHT4X_MEAS_DELAY_HPM + SHT4X_DELAY_EXTRA);
>
> ret = i2c_master_recv(client, raw_data, SHT4X_RESPONSE_LENGTH);
> if (ret != SHT4X_RESPONSE_LENGTH) {
>

\
 
 \ /
  Last update: 2021-11-20 22:09    [W:0.065 / U:0.688 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site