On 2 May 2013 11:10, Tomasz Figa <tomasz.figa@xxxxxxxxx> wrote: > Hi Naveen, > > On Thursday 02 of May 2013 11:01:03 Naveen Krishna Chatradhi wrote: >> From: Naveen Krishna Chatradhi <ch.naveen@xxxxxxxxxxx> >> >> This patch does the following >> 1. use wait_for_completion_timeout instead of >> wait_for_completion_interruptible_timeout >> 2. Reset software if a timeout happens. >> 3. Also reduce the timeout to 100milli secs > > I wonder what this patch is trying to fix. In what conditions can an ADC > conversion time out? > > Sorry if it was already explained in discussion. Still, I think that > commit message of a patch should explain why it is needed. The discussion started with a bug reported by Dan Carpenter http://www.gossamer-threads.com/lists/linux/kernel/1693284?page=last and during the discussion we found out the return cases of wait_for_completion_interruptible_timeout() were not handled properly. so we implemented hw_reset during the error cases. As such ISR only does a regiser access. Which may never timeout. This patch reduces the timeout and removes the use of interruptible. As, ADC's ISR would be too fast to handle the interruptible operation. Now i see, there is nothing much this driver is fixing. As you suggest, the subject can be little less harsh. > > Best regards, > Tomasz Thanks for the review. Naveen > >> Note: submitted for review at >> https://patchwork.kernel.org/patch/2279591/ >> >> Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@xxxxxxxxxxx> >> Cc: Doug Anderson <dianders@xxxxxxxxxxxx> >> Cc: Lars-Peter Clausen <lars@xxxxxxxxxx> >> --- >> Changes since v1: >> As per discussion at >> http://marc.info/?l=linux-kernel&m=136517637228869&w=3 >> >> This patch does the following >> 1. use wait_for_completion_timeout instead of >> wait_for_completion_interruptible_timeout >> 2. Reset software if a timeout happens. >> 3. Also reduce the timeout to 100milli secs >> >> drivers/iio/adc/exynos_adc.c | 73 >> ++++++++++++++++++++++++------------------ 1 file changed, 42 >> insertions(+), 31 deletions(-) >> >> diff --git a/drivers/iio/adc/exynos_adc.c b/drivers/iio/adc/exynos_adc.c >> index 9f3a8ef..a400bb8 100644 >> --- a/drivers/iio/adc/exynos_adc.c >> +++ b/drivers/iio/adc/exynos_adc.c >> @@ -81,7 +81,7 @@ enum adc_version { >> #define ADC_CON_EN_START (1u << 0) >> #define ADC_DATX_MASK 0xFFF >> >> -#define EXYNOS_ADC_TIMEOUT (msecs_to_jiffies(1000)) >> +#define EXYNOS_ADC_TIMEOUT (msecs_to_jiffies(100)) >> >> struct exynos_adc { >> void __iomem *regs; >> @@ -111,6 +111,35 @@ static inline unsigned int >> exynos_adc_get_version(struct platform_device *pdev) return (unsigned >> int)match->data; >> } >> >> +static void exynos_adc_hw_init(struct exynos_adc *info) >> +{ >> + u32 con1, con2; >> + int delay; >> + >> + if (info->version == ADC_V2) { >> + con1 = ADC_V2_CON1_SOFT_RESET; >> + writel(con1, ADC_V2_CON1(info->regs)); >> + >> + /* ADC H/W requires 25PCLKs before other register access > */ >> + delay = DIV_ROUND_UP(25 * 1000000, clk_get_rate(info- >>clk)); >> + udelay(delay); >> + >> + con2 = ADC_V2_CON2_OSEL | ADC_V2_CON2_ESEL | >> + ADC_V2_CON2_HIGHF | ADC_V2_CON2_C_TIME(0); >> + writel(con2, ADC_V2_CON2(info->regs)); >> + >> + /* Enable interrupts */ >> + writel(1, ADC_V2_INT_EN(info->regs)); >> + } else { >> + /* set default prescaler values and Enable prescaler */ >> + con1 = ADC_V1_CON_PRSCLV(49) | ADC_V1_CON_PRSCEN; >> + >> + /* Enable 12-bit ADC resolution */ >> + con1 |= ADC_V1_CON_RES; >> + writel(con1, ADC_V1_CON(info->regs)); >> + } >> +} >> + >> static int exynos_read_raw(struct iio_dev *indio_dev, >> struct iio_chan_spec const *chan, >> int *val, >> @@ -120,6 +149,7 @@ static int exynos_read_raw(struct iio_dev >> *indio_dev, struct exynos_adc *info = iio_priv(indio_dev); >> unsigned long timeout; >> u32 con1, con2; >> + int ret; >> >> if (mask != IIO_CHAN_INFO_RAW) >> return -EINVAL; >> @@ -144,16 +174,21 @@ static int exynos_read_raw(struct iio_dev >> *indio_dev, ADC_V1_CON(info->regs)); >> } >> >> - timeout = wait_for_completion_interruptible_timeout >> + timeout = wait_for_completion_timeout >> (&info->completion, EXYNOS_ADC_TIMEOUT); >> - *val = info->value; >> >> - mutex_unlock(&indio_dev->mlock); >> + if (timeout == 0) { >> + dev_warn(&indio_dev->dev, "Conversion timed out > reseting\n"); >> + exynos_adc_hw_init(info); >> + ret = -ETIMEDOUT; >> + } else { >> + *val = info->value; >> + ret = IIO_VAL_INT; >> + } >> >> - if (timeout == 0) >> - return -ETIMEDOUT; >> + mutex_unlock(&indio_dev->mlock); >> >> - return IIO_VAL_INT; >> + return ret; >> } >> >> static irqreturn_t exynos_adc_isr(int irq, void *dev_id) >> @@ -225,30 +260,6 @@ static int exynos_adc_remove_devices(struct device >> *dev, void *c) return 0; >> } >> >> -static void exynos_adc_hw_init(struct exynos_adc *info) >> -{ >> - u32 con1, con2; >> - >> - if (info->version == ADC_V2) { >> - con1 = ADC_V2_CON1_SOFT_RESET; >> - writel(con1, ADC_V2_CON1(info->regs)); >> - >> - con2 = ADC_V2_CON2_OSEL | ADC_V2_CON2_ESEL | >> - ADC_V2_CON2_HIGHF | ADC_V2_CON2_C_TIME(0); >> - writel(con2, ADC_V2_CON2(info->regs)); >> - >> - /* Enable interrupts */ >> - writel(1, ADC_V2_INT_EN(info->regs)); >> - } else { >> - /* set default prescaler values and Enable prescaler */ >> - con1 = ADC_V1_CON_PRSCLV(49) | ADC_V1_CON_PRSCEN; >> - >> - /* Enable 12-bit ADC resolution */ >> - con1 |= ADC_V1_CON_RES; >> - writel(con1, ADC_V1_CON(info->regs)); >> - } >> -} >> - >> static int exynos_adc_probe(struct platform_device *pdev) >> { >> struct exynos_adc *info = NULL; -- Shine bright, (: Nav :) -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
