Thread (88 messages) 88 messages, 4 authors, 2021-09-05
STALE1729d
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[PATCH 13/40] mfd: ti_am335x_tscadc: Reword the comment explaining the dividers

From: Miquel Raynal <miquel.raynal@bootlin.com>
Date: 2021-08-25 15:32:43
Also in: linux-devicetree, linux-iio, linux-input, linux-omap
Subsystem: multifunction devices (mfd), the rest · Maintainers: Lee Jones, Linus Torvalds

The comment misses the main information which is that we assume that a
sample takes 15 ADC clock cycles to be generated. Let's take the
occasion to rework a little bit this comment.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/mfd/ti_am335x_tscadc.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/mfd/ti_am335x_tscadc.c b/drivers/mfd/ti_am335x_tscadc.c
index 0fef35e1e64b..3afe22680973 100644
--- a/drivers/mfd/ti_am335x_tscadc.c
+++ b/drivers/mfd/ti_am335x_tscadc.c
@@ -195,12 +195,12 @@ static	int ti_tscadc_probe(struct platform_device *pdev)
 	pm_runtime_get_sync(&pdev->dev);
 
 	/*
-	 * The TSC_ADC_Subsystem has 2 clock domains
-	 * OCP_CLK and ADC_CLK.
-	 * The ADC clock is expected to run at target of 3MHz,
-	 * and expected to capture 12-bit data at a rate of 200 KSPS.
-	 * The TSC_ADC_SS controller design assumes the OCP clock is
-	 * at least 6x faster than the ADC clock.
+	 * The TSC_ADC_Subsystem has 2 clock domains: OCP_CLK and ADC_CLK.
+	 * ADCs produce a 12-bit sample every 15 ADC_CLK cycles.
+	 * am33xx ADCs expect to capture 200ksps.
+	 * We need the ADC clocks to run at 3MHz.
+	 * This frequency is valid since TSC_ADC_SS controller design
+	 * assumes the OCP clock is at least 6x faster than the ADC clock.
 	 */
 	clk = devm_clk_get(&pdev->dev, "adc_tsc_fck");
 	if (IS_ERR(clk)) {
-- 
2.27.0
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