linux-kernel - Re: [linux-sunxi] [PATCH 1/7] pinctrl: sunxi: add support for pin controllers without bus gate

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Date:   Thu, 11 Jan 2018 18:15:21 +0800
From:   Icenowy Zheng <icenowy@...c.io>
To:     andre.przywara@....com, Andre Przywara <andre.przywara@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Linus Walleij <linus.walleij@...aro.org>
CC:     linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-sunxi@...glegroups.com
Subject: Re: [linux-sunxi] [PATCH 1/7] pinctrl: sunxi: add support for pin controllers without bus gate



于 2018年1月11日 GMT+08:00 下午6:08:19, Andre Przywara <andre.przywara@....com> 写到:
>Hi,
>
>On 06/01/18 04:23, Icenowy Zheng wrote:
>> The Allwinner H6 pin controllers (both the main one and the CPUs one)
>> have no bus gate clocks.
>> 
>> Add support for this kind of pin controllers.
>> 
>> Signed-off-by: Icenowy Zheng <icenowy@...c.io>
>> ---
>>  drivers/pinctrl/sunxi/pinctrl-sunxi.c | 30
>++++++++++++++++++++----------
>>  drivers/pinctrl/sunxi/pinctrl-sunxi.h |  1 +
>>  2 files changed, 21 insertions(+), 10 deletions(-)
>> 
>> diff --git a/drivers/pinctrl/sunxi/pinctrl-sunxi.c
>b/drivers/pinctrl/sunxi/pinctrl-sunxi.c
>> index 4b6cb25bc796..68cd505679d9 100644
>> --- a/drivers/pinctrl/sunxi/pinctrl-sunxi.c
>> +++ b/drivers/pinctrl/sunxi/pinctrl-sunxi.c
>> @@ -1182,7 +1182,12 @@ static int sunxi_pinctrl_setup_debounce(struct
>sunxi_pinctrl *pctl,
>>  	unsigned int hosc_div, losc_div;
>>  	struct clk *hosc, *losc;
>>  	u8 div, src;
>> -	int i, ret;
>> +	int i, ret, clk_count;
>> +
>> +	if (pctl->desc->without_bus_gate)
>> +		clk_count = 2;
>> +	else
>> +		clk_count = 3;
>>  
>>  	/* Deal with old DTs that didn't have the oscillators */
>>  	if (of_count_phandle_with_args(node, "clocks", "#clock-cells") !=
>3)
>> @@ -1360,15 +1365,19 @@ int sunxi_pinctrl_init_with_variant(struct
>platform_device *pdev,
>>  			goto gpiochip_error;
>>  	}
>>  
>> -	clk = devm_clk_get(&pdev->dev, NULL);
>> -	if (IS_ERR(clk)) {
>> -		ret = PTR_ERR(clk);
>> -		goto gpiochip_error;
>> -	}
>> +	if (!desc->without_bus_gate) {
>
>Do we really need explicit support for that case?
>Can't we have something that works automatically?

It can be a sanity check. When a SoC comes with bus gate
support but no apb is provided, there's something wrong.

>
>if (node has clock-names property)		(A)
>	use clocks as enumerated and named there
>else if (node has one clock reference)		(B)
>	use this as gate clock, no debounce support
>else if (node has no clock property at all)	(C)
>	no gate clock needed, no debounce support

This should not happen in practice, as no gate clock is implemented
after debounce.

>
>On top of that we should add the clock-names property to all DTs, even
>for those with only a "apb" clock. Shouldn't hurt existing kernels.
>Possibly even add debounce support for those on the way, if applicable.
>
>So we would just support case (B) and (C) for legacy reasons.
>
>Does that make sense?
>
>Cheers,
>Andre.
>
>> +		clk = devm_clk_get(&pdev->dev, NULL);
>> +		if (IS_ERR(clk)) {
>> +			ret = PTR_ERR(clk);
>> +			goto gpiochip_error;
>> +		}
>>  
>> -	ret = clk_prepare_enable(clk);
>> -	if (ret)
>> -		goto gpiochip_error;
>> +		ret = clk_prepare_enable(clk);
>> +		if (ret)
>> +			goto gpiochip_error;
>> +	} else {
>> +		clk = NULL;
>> +	}
>>  
>>  	pctl->irq = devm_kcalloc(&pdev->dev,
>>  				 pctl->desc->irq_banks,
>> @@ -1425,7 +1434,8 @@ int sunxi_pinctrl_init_with_variant(struct
>platform_device *pdev,
>>  	return 0;
>>  
>>  clk_error:
>> -	clk_disable_unprepare(clk);
>> +	if (clk)
>> +		clk_disable_unprepare(clk);
>>  gpiochip_error:
>>  	gpiochip_remove(pctl->chip);
>>  	return ret;
>> diff --git a/drivers/pinctrl/sunxi/pinctrl-sunxi.h
>b/drivers/pinctrl/sunxi/pinctrl-sunxi.h
>> index 11b128f54ed2..ccb6230f0bb5 100644
>> --- a/drivers/pinctrl/sunxi/pinctrl-sunxi.h
>> +++ b/drivers/pinctrl/sunxi/pinctrl-sunxi.h
>> @@ -113,6 +113,7 @@ struct sunxi_pinctrl_desc {
>>  	unsigned			irq_bank_base;
>>  	bool				irq_read_needs_mux;
>>  	bool				disable_strict_mode;
>> +	bool				without_bus_gate;
>>  };
>>  
>>  struct sunxi_pinctrl_function {
>>