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From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Jonathan Cameron <jic23@kernel.org>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
	Rob Herring <robh+dt@kernel.org>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	Lee Jones <lee.jones@linaro.org>,
	bcousson@baylibre.com, Tony Lindgren <tony@atomide.com>
Cc: linux-iio@vger.kernel.org, devicetree@vger.kernel.org,
	linux-input@vger.kernel.org, linux-omap@vger.kernel.org,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Lokesh Vutla <lokeshvutla@ti.com>,
	Tero Kristo <kristo@kernel.org>,
	Ryan Barnett <ryan.barnett@collins.com>,
	Grygorii Strashko <grygorii.strashko@ti.com>,
	Jason Reeder <jreeder@ti.com>,
	Miquel Raynal <miquel.raynal@bootlin.com>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>
Subject: [PATCH v2 13/46] mfd: ti_am335x_tscadc: Reword the comment explaining the dividers
Date: Thu,  2 Sep 2021 23:51:11 +0200	[thread overview]
Message-ID: <20210902215144.507243-14-miquel.raynal@bootlin.com> (raw)
In-Reply-To: <20210902215144.507243-1-miquel.raynal@bootlin.com>

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>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.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 984206521eca..177d1244a677 100644
--- a/drivers/mfd/ti_am335x_tscadc.c
+++ b/drivers/mfd/ti_am335x_tscadc.c
@@ -201,12 +201,12 @@ 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


  parent reply	other threads:[~2021-09-02 21:52 UTC|newest]

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-02 21:50 [PATCH v2 00/46] TI AM437X ADC1 Miquel Raynal
2021-09-02 21:50 ` [PATCH v2 01/46] clk: ti: am43xx: Add clkctrl data for am43xx ADC1 Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 02/46] dt-bindings: mfd: ti,am3359-tscadc: Add a yaml description for this MFD Miquel Raynal
2021-09-03 16:05   ` Rob Herring
2021-09-05 11:57   ` Jonathan Cameron
2021-09-02 21:51 ` [PATCH v2 03/46] dt-bindings: touchscreen: ti,am3359-tsc: New yaml description Miquel Raynal
2021-09-03 16:06   ` Rob Herring
2021-09-05 11:59   ` Jonathan Cameron
2021-09-02 21:51 ` [PATCH v2 04/46] dt-bindings: iio: adc: ti,am3359-adc: " Miquel Raynal
2021-09-03 16:07   ` Rob Herring
2021-09-02 21:51 ` [PATCH v2 05/46] dt-bindings: touchscreen: ti,am3359-tsc: Remove deprecated text file Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 06/46] dt-bindings: mfd: ti,am3359-tscadc: Describe am4372 MFD compatible Miquel Raynal
2021-09-05 12:01   ` Jonathan Cameron
2021-09-07 19:04   ` Rob Herring
2021-09-02 21:51 ` [PATCH v2 07/46] dt-bindings: iio: adc: ti,am3359-adc: Describe am4372 ADC compatible Miquel Raynal
2021-09-07 19:05   ` Rob Herring
2021-09-02 21:51 ` [PATCH v2 08/46] mfd: ti_am335x_tscadc: Replace license text with SPDX tag Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 09/46] mfd: ti_am335x_tscadc: Fix style Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 10/46] mfd: ti_am335x_tscadc: Drop extra spacing when declaring stack variables Miquel Raynal
2021-09-05 12:03   ` Jonathan Cameron
2021-09-02 21:51 ` [PATCH v2 11/46] mfd: ti_am335x_tscadc: Ensure a balanced number of node get/put Miquel Raynal
2021-09-05 12:06   ` Jonathan Cameron
2021-09-02 21:51 ` [PATCH v2 12/46] mfd: ti_am335x_tscadc: Get rid of useless gotos Miquel Raynal
2021-09-02 21:51 ` Miquel Raynal [this message]
2021-09-02 21:51 ` [PATCH v2 14/46] mfd: ti_am335x_tscadc: Don't search the tree for our clock Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 15/46] mfd: ti_am335x_tscadc: Simplify divisor calculation Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 16/46] mfd: ti_am335x_tscadc: Move the driver structure allocation earlier Miquel Raynal
2021-09-05 12:09   ` Jonathan Cameron
2021-09-02 21:51 ` [PATCH v2 17/46] mfd: ti_am335x_tscadc: Use driver data Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 18/46] mfd: ti_am335x_tscadc: Mimic the probe from resume() Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 19/46] mfd: ti_am335x_tscadc: Drop useless variables from the driver structure Miquel Raynal
2021-09-05 12:11   ` Jonathan Cameron
2021-09-02 21:51 ` [PATCH v2 20/46] mfd: ti_am335x_tscadc: Always provide an idle configuration Miquel Raynal
2021-09-05 12:13   ` Jonathan Cameron
2021-09-02 21:51 ` [PATCH v2 21/46] mfd: ti_am335x_tscadc: Reorder the initialization steps Miquel Raynal
2021-09-05 12:18   ` Jonathan Cameron
2021-09-02 21:51 ` [PATCH v2 22/46] mfd: ti_am335x_tscadc: Gather the ctrl register logic in one place Miquel Raynal
2021-09-05 12:20   ` Jonathan Cameron
2021-09-02 21:51 ` [PATCH v2 23/46] mfd: ti_am335x_tscadc: Replace the header license text with SPDX tag Miquel Raynal
2021-09-05 12:21   ` Jonathan Cameron
2021-09-02 21:51 ` [PATCH v2 24/46] mfd: ti_am335x_tscadc: Fix header spacing Miquel Raynal
2021-09-05 12:22   ` Jonathan Cameron
2021-09-02 21:51 ` [PATCH v2 25/46] mfd: ti_am335x_tscadc: Use BIT() and GENMASK() when relevant in the header Miquel Raynal
2021-09-05 13:09   ` Jonathan Cameron
2021-09-02 21:51 ` [PATCH v2 26/46] mfd: ti_am335x_tscadc: Use FIELD_PREP() " Miquel Raynal
2021-09-05 13:13   ` Jonathan Cameron
2021-09-15  7:48     ` Miquel Raynal
2021-09-19 15:49       ` Jonathan Cameron
2021-09-02 21:51 ` [PATCH v2 27/46] mfd: ti_am335x_tscadc: Rename the subsystem enable macro Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 28/46] mfd: ti_am335x_tscadc: Add TSC prefix in certain macros Miquel Raynal
2021-09-05 13:15   ` Jonathan Cameron
2021-09-02 21:51 ` [PATCH v2 29/46] mfd: ti_am335x_tscadc: Rename a variable Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 30/46] mfd: ti_am335x_tscadc: Fix an error message Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 31/46] mfd: ti_am335x_tscadc: Add a boolean to clarify the presence of a touchscreen Miquel Raynal
2021-09-05 13:17   ` Jonathan Cameron
2021-09-02 21:51 ` [PATCH v2 32/46] mfd: ti_am335x_tscadc: Introduce has_tsc Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 33/46] mfd: ti_am335x_tscadc: Move control register configuration Miquel Raynal
2021-09-03 13:24   ` Grygorii Strashko
2021-09-05 13:18     ` Jonathan Cameron
2021-09-05 13:22       ` Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 34/46] mfd: ti_am335x_tscadc: Add ADC1/magnetic reader support Miquel Raynal
2021-09-05 13:23   ` Jonathan Cameron
2021-09-14 18:25     ` Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 35/46] mfd: ti_am335x_tscadc: Support the correctly spelled DT property Miquel Raynal
2021-09-05 13:24   ` Jonathan Cameron
2021-09-02 21:51 ` [PATCH v2 36/46] iio: adc: ti_am335x_adc: Wait the idle state to avoid stalls Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 37/46] iio: adc: ti_am335x_adc: Replace license text with SPDX tag Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 38/46] iio: adc: ti_am335x_adc: Fix style Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 39/46] iio: adc: ti_am335x_adc: Get rid of useless gotos Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 40/46] iio: adc: ti_am335x_adc: Gather the checks on the delays Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 41/46] iio: adc: ti_am335x_adc: Add a unit to the timeout delay Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 42/46] iio: adc: ti_am335x_adc: Add the scale information Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 43/46] iio: adc: ti_am335x_adc: Add the am437x compatible Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 44/46] ARM: dts: am437x-cm-t43: Use a correctly spelled DT property Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 45/46] ARM: dts: am43xx: Describe the magnetic reader/ADC1 hardware module Miquel Raynal
2021-09-02 22:17   ` Miquel Raynal
2021-09-02 21:51 ` [PATCH v2 46/46] ARM: dts: am437x-gp-evm: enable ADC1 Miquel Raynal

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