Re: [PATCH v2 21/46] mfd: ti_am335x_tscadc: Reorder the initialization steps
From: Jonathan Cameron <jic23@kernel.org>
Date: 2021-09-05 12:15:31
Also in:
linux-devicetree, linux-input, linux-omap
On Thu, 2 Sep 2021 23:51:19 +0200 Miquel Raynal [off-list ref] wrote:
TI AM335X TRM [1] states that most of the configuration should be set in the control register in the first place, before actually enabling the hardware with the subsystem enable bit. So far only half of the configuration was made in the first step (before enabling the "subsystem"), which does not make really sense. Also, the probe and the resume patch were acting differently. Let's harmonize all this by following these steps: 1/ Configure the CLKDIV register 2/ Configure the CTRL register 3/ Configure the idle configuration 4/ Really enable the device by rewriting the CTRL register with the subsystem enable bit set. [1] https://www.ti.com/lit/pdf/spruh73 Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
This tidies up the other patches which is good. Now I haven't checked the new order against the datasheet but it now does things as you describe so I'm assuming that's fine. Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
quoted hunk ↗ jump to hunk
--- drivers/mfd/ti_am335x_tscadc.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)diff --git a/drivers/mfd/ti_am335x_tscadc.c b/drivers/mfd/ti_am335x_tscadc.c index 5f189da99468..61f878c7593b 100644 --- a/drivers/mfd/ti_am335x_tscadc.c +++ b/drivers/mfd/ti_am335x_tscadc.c@@ -221,8 +221,6 @@ static int ti_tscadc_probe(struct platform_device *pdev) /* Set the control register bits */ ctrl = CNTRLREG_STEPCONFIGWRT | CNTRLREG_STEPID; - regmap_write(tscadc->regmap, REG_CTRL, ctrl); - if (tsc_wires > 0) { tscadc->tsc_wires = tsc_wires; if (tsc_wires == 5)@@ -230,6 +228,7 @@ static int ti_tscadc_probe(struct platform_device *pdev) else ctrl |= CNTRLREG_4WIRE | CNTRLREG_TSCENB; } + regmap_write(tscadc->regmap, REG_CTRL, ctrl); tscadc_idle_config(tscadc);@@ -315,9 +314,9 @@ static int __maybe_unused tscadc_resume(struct device *dev) pm_runtime_get_sync(dev); /* context restore */ - ctrl = CNTRLREG_STEPCONFIGWRT | CNTRLREG_STEPID; - regmap_write(tscadc->regmap, REG_CTRL, ctrl); + regmap_write(tscadc->regmap, REG_CLKDIV, tscadc->clk_div); + ctrl = CNTRLREG_STEPCONFIGWRT | CNTRLREG_STEPID; if (tscadc->tsc_wires > 0) { if (tscadc->tsc_wires == 5) ctrl |= CNTRLREG_5WIRE | CNTRLREG_TSCENB;@@ -325,13 +324,13 @@ static int __maybe_unused tscadc_resume(struct device *dev) ctrl |= CNTRLREG_4WIRE | CNTRLREG_TSCENB; } + regmap_write(tscadc->regmap, REG_CTRL, ctrl); + tscadc_idle_config(tscadc); ctrl |= CNTRLREG_TSCSSENB; regmap_write(tscadc->regmap, REG_CTRL, ctrl); - regmap_write(tscadc->regmap, REG_CLKDIV, tscadc->clk_div); - return 0; }