From fda29dbac9e6604f8eeb660953a2bef360514dc7 Mon Sep 17 00:00:00 2001 From: Martin Blumenstingl Date: Tue, 31 Oct 2017 21:01:46 +0100 Subject: [PATCH] iio: adc: meson-saradc: fix the clock frequency on Meson8 and Meson8b GX SoCs use a 1.2 MHz ADC clock, while the older SoCs use a 1.14 MHz clock. A comment in the driver from Amlogic's GPL kernel says that it's running at 1.28 MHz. However, it's actually programming a divider of 20 + 1. With a XTAL clock of 24 MHz this results in a frequency of 1.14 MHz. (their calculation might be based on a 27 MHz XTAL clock, but this is not what we have on the Meson8 and Meson8b SoCs). The ADC was still working with the 1.2MHz clock. In my own tests I did not see a difference between 1.2 and 1.14 MHz (regardless of the clock frequency used, the ADC results were identical). Signed-off-by: Martin Blumenstingl Signed-off-by: Jonathan Cameron Signed-off-by: Greg Kroah-Hartman --- drivers/iio/adc/meson_saradc.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/iio/adc/meson_saradc.c b/drivers/iio/adc/meson_saradc.c index 48fdbb3a..24025f17 100644 --- a/drivers/iio/adc/meson_saradc.c +++ b/drivers/iio/adc/meson_saradc.c @@ -221,6 +221,7 @@ enum meson_sar_adc_chan7_mux_sel { struct meson_sar_adc_data { bool has_bl30_integration; + unsigned long clock_rate; u32 bandgap_reg; unsigned int resolution; const char *name; @@ -683,7 +684,7 @@ static int meson_sar_adc_init(struct iio_dev *indio_dev) return ret; } - ret = clk_set_rate(priv->adc_clk, 1200000); + ret = clk_set_rate(priv->adc_clk, priv->data->clock_rate); if (ret) { dev_err(indio_dev->dev.parent, "failed to set adc clock rate\n"); @@ -856,6 +857,7 @@ static const struct iio_info meson_sar_adc_iio_info = { static const struct meson_sar_adc_data meson_sar_adc_meson8_data = { .has_bl30_integration = false, + .clock_rate = 1150000, .bandgap_reg = MESON_SAR_ADC_DELTA_10, .regmap_config = &meson_sar_adc_regmap_config_meson8, .resolution = 10, @@ -864,6 +866,7 @@ static const struct meson_sar_adc_data meson_sar_adc_meson8_data = { static const struct meson_sar_adc_data meson_sar_adc_meson8b_data = { .has_bl30_integration = false, + .clock_rate = 1150000, .bandgap_reg = MESON_SAR_ADC_DELTA_10, .regmap_config = &meson_sar_adc_regmap_config_meson8, .resolution = 10, @@ -872,6 +875,7 @@ static const struct meson_sar_adc_data meson_sar_adc_meson8b_data = { static const struct meson_sar_adc_data meson_sar_adc_gxbb_data = { .has_bl30_integration = true, + .clock_rate = 1200000, .bandgap_reg = MESON_SAR_ADC_REG11, .regmap_config = &meson_sar_adc_regmap_config_gxbb, .resolution = 10, @@ -880,6 +884,7 @@ static const struct meson_sar_adc_data meson_sar_adc_gxbb_data = { static const struct meson_sar_adc_data meson_sar_adc_gxl_data = { .has_bl30_integration = true, + .clock_rate = 1200000, .bandgap_reg = MESON_SAR_ADC_REG11, .regmap_config = &meson_sar_adc_regmap_config_gxbb, .resolution = 12, @@ -888,6 +893,7 @@ static const struct meson_sar_adc_data meson_sar_adc_gxl_data = { static const struct meson_sar_adc_data meson_sar_adc_gxm_data = { .has_bl30_integration = true, + .clock_rate = 1200000, .bandgap_reg = MESON_SAR_ADC_REG11, .regmap_config = &meson_sar_adc_regmap_config_gxbb, .resolution = 12, -- 2.7.4