On Wed, 31 May 2017, Charles Keepax wrote:
> Very fast systems may violate the minimum constraints for time the reset
> line needs to remain low, or communicate with the device too soon after
> releasing the reset. Fix this by adding some delays in to allow the chip
> to properly reset, also factor out the reset into a function as it is
> likely it will be re-used in later additions to the driver.
>
> Signed-off-by: Charles Keepax <ckeepax@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
> ---
> sound/soc/codecs/cs35l35.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/sound/soc/codecs/cs35l35.c b/sound/soc/codecs/cs35l35.c
> index 375be49..f1ee184 100644
> --- a/sound/soc/codecs/cs35l35.c
> +++ b/sound/soc/codecs/cs35l35.c
> @@ -162,6 +162,14 @@ static bool cs35l35_precious_register(struct device *dev, unsigned int reg)
> }
> }
>
> +static void cs35l35_reset(struct cs35l35_private *cs35l35)
> +{
> + gpiod_set_value_cansleep(cs35l35->reset_gpio, 0);
> + usleep_range(2000, 2100);
> + gpiod_set_value_cansleep(cs35l35->reset_gpio, 1);
> + usleep_range(1000, 1100);
> +}
> +
> static int cs35l35_wait_for_pdn(struct cs35l35_private *cs35l35)
> {
> int ret;
> @@ -1536,7 +1544,7 @@ static int cs35l35_i2c_probe(struct i2c_client *i2c_client,
> }
> }
>
> - gpiod_set_value_cansleep(cs35l35->reset_gpio, 1);
> + cs35l35_reset(cs35l35);
>
> init_completion(&cs35l35->pdn_done);
>
Acked-by: Paul Handrigan <Paul.Handrigan@xxxxxxxxxx>
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