linux-kernel - Re: [PATCH 1/4] iio: adc: rockchip_saradc: reset saradc controller before programming it

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Date:	Tue, 26 Jul 2016 18:49:56 +0800
From:	Caesar Wang <wxt@...k-chips.com>
To:	John Keeping <john@...anate.com>, Heiko Stuebner <heiko@...ech.de>
CC:	Caesar Wang <wxt@...k-chips.com>, devicetree@...r.kernel.org,
	linux-iio@...r.kernel.org, dianders@...omium.org,
	linux-kernel@...r.kernel.org, linux-rockchip@...ts.infradead.org,
	robh+dt@...nel.org, linux@...ck-us.net, jic23@...nel.org
Subject: Re: [PATCH 1/4] iio: adc: rockchip_saradc: reset saradc controller
 before programming it

On 2016年07月26日 17:00, John Keeping wrote:
> On Tue, 26 Jul 2016 14:11:47 +0800, Caesar Wang wrote:
>
>> SARADC controller needs to be reset before programming it, otherwise
>> it will not function properly.
>>
>> Signed-off-by: Caesar Wang <wxt@...k-chips.com>
>> Cc: Jonathan Cameron <jic23@...nel.org>
>> Cc: Heiko Stuebner <heiko@...ech.de>
>> Cc: Rob Herring <robh+dt@...nel.org>
>> Cc: linux-iio@...r.kernel.org
>> Cc: linux-rockchip@...ts.infradead.org
>> ---
>>
>> diff --git a/drivers/iio/adc/rockchip_saradc.c b/drivers/iio/adc/rockchip_saradc.c
>> index f9ad6c2..2f0e110 100644
>> --- a/drivers/iio/adc/rockchip_saradc.c
>> +++ b/drivers/iio/adc/rockchip_saradc.c
>> @@ -218,6 +231,13 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
>>   	if (IS_ERR(info->regs))
>>   		return PTR_ERR(info->regs);
>>   
>> +	info->reset = devm_reset_control_get(&pdev->dev, "saradc-apb");
>> +	if (IS_ERR(info->reset)) {
>> +		ret = PTR_ERR(info->reset);
>> +		dev_err(&pdev->dev, "failed to get saradc reset: %d\n", ret);
>> +		return ret;
>> +	}
> Does this need to handle ENOENT so as to avoid failing with old device
> tree blobs?

I'm no sure why we have to support the old device tree,
We can apply this series patches if we need to support the reset property.
---

Maybe, I can follow you suggestion to handle the ENOENT, as following:

+ /*
+ * The reset should be an optional property, as it should work
+ * with old devicetrees as well
+ */
+ info->reset = devm_reset_control_get(&pdev->dev, "saradc-apb");
+ if (IS_ERR(info->reset)) {
+ if (PTR_ERR(info->reset) == -EPROBE_DEFER) {
+ ret = -EPROBE_DEFER;
+ return ret;
+ }
+ dev_dbg(&pdev->dev, "no reset control found\n");
+ info->reset = NULL;
+ }
...

+ if (info->reset)
+ rockchip_saradc_reset_controller(info->reset);
+

How about it?

-
Caesar
>
> _______________________________________________
> Linux-rockchip mailing list
> Linux-rockchip@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-rockchip

-- 
caesar wang | software engineer | wxt@...k-chip.com

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