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SubjectRe: [PATCH v6 3/6] mfd: ti_am335x_tscadc: Remove unwanted reg_se_cache save


On Tuesday 20 January 2015 09:34 PM, Lee Jones wrote:
> On Tue, 20 Jan 2015, R, Vignesh wrote:
>> 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@ti.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@linaro.org>
>>>
>>> Can this patch be applied on its own?
>>>
>>
>> I prefer to wait until input patches are picked up.
>
> I have no problem with that, but is there a technical reason why?
>

Nothing, in particular. This patch alone has no impact on the
performance of TSC/ADC unit. Patch 2/6 is necessary to observe the
changes caused by this series. Hence, please wait until those 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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