| Message ID | 1387385577-24447-4-git-send-email-bigeasy@linutronix.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, 18 Dec 2013, Sebastian Andrzej Siewior wrote: > The purpose of reg_se_cache has been defeated. It should avoid the > read-back of the register to avoid the latency and the fact that the > bits are reset to 0 after the individual conversation took place. > > The reason why this is required like this to work, is that read-back of > the register removes the bits of the ADC so they do not start another > conversation after the register is re-written from the TSC side for the > update. > To avoid the unrequired read-back I introduce a "set adc" variant which > does not update the cache mask. After the conversation completes, the > register bit is removed from the SE reister anyway and we don't plan a > new conversation "any time soon". > This is a small preparation for a larger sync-rework. > > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > --- > drivers/iio/adc/ti_am335x_adc.c | 2 +- > drivers/mfd/ti_am335x_tscadc.c | 12 ++++++++++-- > include/linux/mfd/ti_am335x_tscadc.h | 1 + > 3 files changed, 12 insertions(+), 3 deletions(-) Looks about right: Acked-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c index e948454..9ad9bd9 100644 --- a/drivers/iio/adc/ti_am335x_adc.c +++ b/drivers/iio/adc/ti_am335x_adc.c @@ -335,7 +335,7 @@ static int tiadc_read_raw(struct iio_dev *indio_dev, return -EBUSY; step_en = get_adc_step_mask(adc_dev); - am335x_tsc_se_set(adc_dev->mfd_tscadc, step_en); + am335x_tsc_se_adc_set(adc_dev->mfd_tscadc, step_en); /* Wait for ADC sequencer to complete sampling */ while (tiadc_readl(adc_dev, REG_ADCFSM) & SEQ_STATUS) { diff --git a/drivers/mfd/ti_am335x_tscadc.c b/drivers/mfd/ti_am335x_tscadc.c index 67d0eb4..2948a41 100644 --- a/drivers/mfd/ti_am335x_tscadc.c +++ b/drivers/mfd/ti_am335x_tscadc.c @@ -58,19 +58,27 @@ void am335x_tsc_se_set(struct ti_tscadc_dev *tsadc, u32 val) unsigned long flags; spin_lock_irqsave(&tsadc->reg_lock, flags); - tsadc->reg_se_cache = tscadc_readl(tsadc, REG_SE); tsadc->reg_se_cache |= val; am335x_tsc_se_update(tsadc); spin_unlock_irqrestore(&tsadc->reg_lock, flags); } EXPORT_SYMBOL_GPL(am335x_tsc_se_set); +void am335x_tsc_se_adc_set(struct ti_tscadc_dev *tsadc, u32 val) +{ + unsigned long flags; + + spin_lock_irqsave(&tsadc->reg_lock, flags); + tscadc_writel(tsadc, REG_SE, tsadc->reg_se_cache | val); + spin_unlock_irqrestore(&tsadc->reg_lock, flags); +} +EXPORT_SYMBOL_GPL(am335x_tsc_se_adc_set); + void am335x_tsc_se_clr(struct ti_tscadc_dev *tsadc, u32 val) { unsigned long flags; spin_lock_irqsave(&tsadc->reg_lock, flags); - tsadc->reg_se_cache = tscadc_readl(tsadc, REG_SE); tsadc->reg_se_cache &= ~val; am335x_tsc_se_update(tsadc); spin_unlock_irqrestore(&tsadc->reg_lock, flags); diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h index 1fe7219..be44a66 100644 --- a/include/linux/mfd/ti_am335x_tscadc.h +++ b/include/linux/mfd/ti_am335x_tscadc.h @@ -177,6 +177,7 @@ static inline struct ti_tscadc_dev *ti_tscadc_dev_get(struct platform_device *p) } void am335x_tsc_se_set(struct ti_tscadc_dev *tsadc, u32 val); +void am335x_tsc_se_adc_set(struct ti_tscadc_dev *tsadc, u32 val); void am335x_tsc_se_clr(struct ti_tscadc_dev *tsadc, u32 val); #endif
The purpose of reg_se_cache has been defeated. It should avoid the read-back of the register to avoid the latency and the fact that the bits are reset to 0 after the individual conversation took place. The reason why this is required like this to work, is that read-back of the register removes the bits of the ADC so they do not start another conversation after the register is re-written from the TSC side for the update. To avoid the unrequired read-back I introduce a "set adc" variant which does not update the cache mask. After the conversation completes, the register bit is removed from the SE reister anyway and we don't plan a new conversation "any time soon". This is a small preparation for a larger sync-rework. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- drivers/iio/adc/ti_am335x_adc.c | 2 +- drivers/mfd/ti_am335x_tscadc.c | 12 ++++++++++-- include/linux/mfd/ti_am335x_tscadc.h | 1 + 3 files changed, 12 insertions(+), 3 deletions(-)