linux-kernel - Re: [PATCH v6 3/6] mfd: ti_am335x_tscadc: Remove unwanted reg_se

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Message-ID: <54BE4CD1.1020709@ti.com>
Date:	Tue, 20 Jan 2015 18:10:49 +0530
From:	"R, Vignesh" <vigneshr@...com>
To:	Lee Jones <lee.jones@...aro.org>
CC:	Jonathan Cameron <jic23@...nel.org>,
	Hartmut Knaack <knaack.h@....de>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Benoit Cousson <bcousson@...libre.com>,
	Tony Lindgren <tony@...mide.com>,
	Russell King <linux@....linux.org.uk>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Peter Meerwald <pmeerw@...erw.net>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Brad Griffis <bgriffis@...com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Sanjeev Sharma <sanjeev_sharma@...tor.com>,
	Jan Kardell <jan.kardell@...liq.com>,
	Felipe Balbi <balbi@...com>, Wolfram Sang <wsa@...-dreams.de>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-omap@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-iio@...r.kernel.org>, <linux-input@...r.kernel.org>
Subject: Re: [PATCH v6 3/6] mfd: ti_am335x_tscadc: Remove unwanted reg_se_cache
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On 1/20/2015 5:23 PM, Lee Jones wrote:
> On Wed, 07 Jan 2015, Vignesh R wrote:
> 
>> In one shot mode, sequencer automatically disables all enabled steps at
>> the end of each cycle. (both ADC steps and TSC steps) Hence these steps
>> need not be saved in reg_se_cache for clearing these steps at a later
>> stage.
>> Also, when ADC wakes up Sequencer should not be busy executing any of the
>> config steps except for the charge step. Previously charge step was 1 ADC
>> clock cycle and hence it was ignored.
>> TSC steps are always disabled at the end of each conversion cycle, hence
>> there is no need to explicitly disable TSC steps by writing 0 to REG_SE.
>>
>> Signed-off-by: Vignesh R <vigneshr@...com>
>> ---
>>
>> v5:
>>  - Remove unnecessary clearing of REG_SE
>>
>>  drivers/mfd/ti_am335x_tscadc.c       | 13 +++++--------
>>  include/linux/mfd/ti_am335x_tscadc.h |  1 +
>>  2 files changed, 6 insertions(+), 8 deletions(-)
> 
> Looks fine.
> 
> For my own reference:
>   Acked-by: Lee Jones <lee.jones@...aro.org>
> 
> Can this patch be applied on its own?
> 

I prefer to wait until input patches are picked up.

>> diff --git a/drivers/mfd/ti_am335x_tscadc.c b/drivers/mfd/ti_am335x_tscadc.c
>> index 467c80e1c4ae..e4e4b22eebc9 100644
>> --- a/drivers/mfd/ti_am335x_tscadc.c
>> +++ b/drivers/mfd/ti_am335x_tscadc.c
>> @@ -68,12 +68,6 @@ static void am335x_tscadc_need_adc(struct ti_tscadc_dev *tsadc)
>>  	DEFINE_WAIT(wait);
>>  	u32 reg;
>>  
>> -	/*
>> -	 * disable TSC steps so it does not run while the ADC is using it. If
>> -	 * write 0 while it is running (it just started or was already running)
>> -	 * then it completes all steps that were enabled and stops then.
>> -	 */
>> -	tscadc_writel(tsadc, REG_SE, 0);
>>  	reg = tscadc_readl(tsadc, REG_ADCFSM);
>>  	if (reg & SEQ_STATUS) {
>>  		tsadc->adc_waiting = true;
>> @@ -86,8 +80,12 @@ static void am335x_tscadc_need_adc(struct ti_tscadc_dev *tsadc)
>>  		spin_lock_irq(&tsadc->reg_lock);
>>  		finish_wait(&tsadc->reg_se_wait, &wait);
>>  
>> +		/*
>> +		 * Sequencer should either be idle or
>> +		 * busy applying the charge step.
>> +		 */
>>  		reg = tscadc_readl(tsadc, REG_ADCFSM);
>> -		WARN_ON(reg & SEQ_STATUS);
>> +		WARN_ON((reg & SEQ_STATUS) && !(reg & CHARGE_STEP));
>>  		tsadc->adc_waiting = false;
>>  	}
>>  	tsadc->adc_in_use = true;
>> @@ -96,7 +94,6 @@ static void am335x_tscadc_need_adc(struct ti_tscadc_dev *tsadc)
>>  void am335x_tsc_se_set_once(struct ti_tscadc_dev *tsadc, u32 val)
>>  {
>>  	spin_lock_irq(&tsadc->reg_lock);
>> -	tsadc->reg_se_cache |= val;
>>  	am335x_tscadc_need_adc(tsadc);
>>  
>>  	tscadc_writel(tsadc, REG_SE, val);
>> diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h
>> index 3f4e994ace2b..1fd50dcfe47c 100644
>> --- a/include/linux/mfd/ti_am335x_tscadc.h
>> +++ b/include/linux/mfd/ti_am335x_tscadc.h
>> @@ -128,6 +128,7 @@
>>  
>>  /* Sequencer Status */
>>  #define SEQ_STATUS BIT(5)
>> +#define CHARGE_STEP		0x11
>>  
>>  #define ADC_CLK			3000000
>>  #define TOTAL_STEPS		16
> 
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