[PATCH] iio: frequency: adrf6780: replace usleep_range() with fsleep()

[Stepan Ionichev <sozdayvek@gmail.com>]

The ADRF6780 datasheet (Rev. D, page 23, ADC section) says:
"Wait approximately 200 us for the ADC to be ready."

fsleep(200) expands to the same usleep_range(200, 250). Use the
flexible sleep helper, which picks the right primitive for the
given microsecond delay.

Replace the generic "Recommended delay for the ADC to be ready"
comment with the datasheet reference so the "why" of the wait is
visible at the call site.

No functional change.

Signed-off-by: Stepan Ionichev <sozdayvek@gmail.com>
---
 drivers/iio/frequency/adrf6780.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/frequency/adrf6780.c b/drivers/iio/frequency/adrf6780.c
index 257fd31a0..9911b5273 100644
--- a/drivers/iio/frequency/adrf6780.c
+++ b/drivers/iio/frequency/adrf6780.c
@@ -188,8 +188,11 @@ static int adrf6780_read_adc_raw(struct adrf6780_state *st, unsigned int *read_v
 	if (ret)
 		goto exit;
 
-	/* Recommended delay for the ADC to be ready*/
-	usleep_range(200, 250);
+	/*
+	 * Per ADRF6780 datasheet (Rev. D, page 23, ADC section),
+	 * wait approximately 200 us for the ADC to be ready.
+	 */
+	fsleep(200);
 
 	ret = __adrf6780_spi_read(st, ADRF6780_REG_ADC_OUTPUT, read_val);
 	if (ret)
-- 
2.43.0