Re: [PATCH] iio: adc: rockchip_saradc: Explicitly disable ADC on probe

On 26/07/16 04:22, Guenter Roeck wrote:

On 07/25/2016 07:51 PM, Caesar Wang wrote:

quoted

Hi Guenter,

Thanks for fixing it.

On 2016年07月26日 03:39, Guenter Roeck wrote:

quoted

If the ADC is read for the first time, the caller gets a timeout error,
and the kernel log shows

read channel() error: -110

The ADC may be enabled on boot, and needs to be explicitly disabled
for a read sequence to work (otherwise there is no completion interrupt).
Disaple it explicitly in the probe function.

Fixes: 44d6f2ef94f9 ("iio: adc: add driver for Rockchip saradc")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
  drivers/iio/adc/rockchip_saradc.c | 3 +++
  1 file changed, 3 insertions(+)

diff --git a/drivers/iio/adc/rockchip_saradc.c b/drivers/iio/adc/rockchip_saradc.c
index f9ad6c2d6821..6aa3271d86b5 100644
--- a/drivers/iio/adc/rockchip_saradc.c
+++ b/drivers/iio/adc/rockchip_saradc.c

@@ -280,6 +280,9 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
          goto err_pclk;
      }
+    /* Make sure ADC is disabled */
+    writel_relaxed(0, info->regs + SARADC_CTRL);

I think we should reset the saradc controller.
Since make sure the reset value is 0 and loader-->kernel may even cause harm, as my experience on tsadc. (drivers/thermal/rockchip_thermal.c)


e.g.:
/**
* Reset SARADC Controller, reset all saradc registers.
*/
static void rockchip_saradc_reset_controller(struct reset_control *reset)
{
reset_control_assert(reset);
usleep_range(10, 20);
reset_control_deassert(reset);
}

..probe()
{
...
rockchip_saradc_reset_controller();
...
}

Ok, I'll give it a try.

Guenter

Could you confirm if this patch is superseded by that
change or not?

quoted

-
Caesar

quoted

+
      platform_set_drvdata(pdev, indio_dev);
      indio_dev->name = dev_name(&pdev->dev);

-- 
To unsubscribe from this list: send the line "unsubscribe linux-iio" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html