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Message-ID: <5796D036.1060101@rock-chips.com>
Date: Tue, 26 Jul 2016 10:51:34 +0800
From: Caesar Wang <wxt@...k-chips.com>
To: Guenter Roeck <linux@...ck-us.net>,
Jonathan Cameron <jic23@...nel.org>,
Heiko Stuebner <heiko@...ech.de>
CC: linux-iio@...r.kernel.org, dianders@...omium.org,
linux-kernel@...r.kernel.org, linux-rockchip@...ts.infradead.org,
Caesar Wang <wxt@...k-chips.com>
Subject: Re: [PATCH] iio: adc: rockchip_saradc: Explicitly disable ADC on
probe
Hi Guenter,
Thanks for fixing it.
On 2016年07月26日 03:39, Guenter Roeck wrote:
> 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@...ck-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();
...
}
-
Caesar
> +
> platform_set_drvdata(pdev, indio_dev);
>
> indio_dev->name = dev_name(&pdev->dev);
--
caesar wang | software engineer | wxt@...k-chip.com
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