Re: [PATCH] iio/adc: ingenic: Fix AUX/VBAT readings when touchscreen is used

Hi Paul,

On 2020-11-03 21:12, Paul Cercueil wrote:

When the command feature of the ADC is used, it is possible to program the ADC, and specify at each step what input should be processed, and in comparison to what reference.

This broke the AUX and battery readings when the touchscreen was enabled, most likely because the CMD feature would change the VREF all the time.

Now, when AUX or battery are read, we temporarily disable the CMD feature, which means that we won't get touchscreen readings in that time frame. But it now gives correct values for AUX / battery, and the touchscreen isn't disabled for long enough to be an actual issue.

Fixes: b96952f498db ("IIO: Ingenic JZ47xx: Add touchscreen mode.") Cc: stable@vger.kernel.org Signed-off-by: Paul Cercueil paul@crapouillou.net

---

drivers/iio/adc/ingenic-adc.c | 33 +++++++++++++++++++++++++++------ 1 file changed, 27 insertions(+), 6 deletions(-)

diff --git a/drivers/iio/adc/ingenic-adc.c b/drivers/iio/adc/ingenic-adc.c index 92b25083e23f..ecaff6a9b716 100644 --- a/drivers/iio/adc/ingenic-adc.c +++ b/drivers/iio/adc/ingenic-adc.c @@ -177,13 +177,12 @@ static void ingenic_adc_set_config(struct ingenic_adc *adc, mutex_unlock(&adc->lock); }

-static void ingenic_adc_enable(struct ingenic_adc *adc,

• 	       int engine,
  

• 	       bool enabled)
  

+static void ingenic_adc_enable_unlocked(struct ingenic_adc *adc,

• 			int engine,
  

• 			bool enabled)
  

{ u8 val;

• mutex_lock(&adc->lock); val = readb(adc->base + JZ_ADC_REG_ENABLE);

  if (enabled)

@@ -192,20 +191,42 @@ static void ingenic_adc_enable(struct ingenic_adc *adc, val &= ~BIT(engine);

writeb(val, adc->base + JZ_ADC_REG_ENABLE); +}

+static void ingenic_adc_enable(struct ingenic_adc *adc,

• 	       int engine,
  

• 	       bool enabled)
  

+{

• mutex_lock(&adc->lock);
• ingenic_adc_enable_unlocked(adc, engine, enabled); mutex_unlock(&adc->lock);

}

static int ingenic_adc_capture(struct ingenic_adc *adc, int engine) {

• u32 cfg; u8 val; int ret;

• ingenic_adc_enable(adc, engine, true);

• /*

• * Disable CMD_SEL temporarily, because it causes wrong VBAT 
  

readings,

• * probably due to the switch of VREF. We must keep the lock here to
  

• * avoid races with the buffer enable/disable functions.
  

• */
  

• mutex_lock(&adc->lock);
• cfg = readl(adc->base + JZ_ADC_REG_CFG);
• writel(cfg & ~JZ_ADC_REG_CFG_CMD_SEL, adc->base + JZ_ADC_REG_CFG);

Redundant empty line.

• ingenic_adc_enable_unlocked(adc, engine, true); ret = readb_poll_timeout(adc->base + JZ_ADC_REG_ENABLE, val, !(val & BIT(engine)), 250, 1000); if (ret)

• ingenic_adc_enable(adc, engine, false);
  

• ingenic_adc_enable_unlocked(adc, engine, false);
  

• writel(cfg, adc->base + JZ_ADC_REG_CFG);

• mutex_unlock(&adc->lock);

  return ret;

}

With the above nitpick corrected: Acked-by: Artur Rojek contact@artur-rojek.eu