Hi, On 22.01.21 11:23, Fabrice Gasnier wrote: > On 1/21/21 7:02 PM, Ahmad Fatoum wrote: >> For non-DMA usage, we have an easy way to associate a timestamp with a >> sample: iio_pollfunc_store_time stores a timestamp in the primary >> trigger IRQ handler and stm32_adc_trigger_handler runs in the IRQ thread >> to push out the buffer along with the timestamp. >> >> For this to work, the driver needs to register an IIO_TIMESTAMP channel. >> Do this. >> >> For DMA, it's not as easy, because we don't push the buffers out of >> stm32_adc_trigger, but out of stm32_adc_dma_buffer_done, which runs in >> a tasklet scheduled after a DMA completion. >> >> Preferably, the DMA controller would copy us the timestamp into that buffer >> as well. Until this is implemented, restrict timestamping support to >> only PIO. For low-frequency sampling, PIO is probably good enough. >> >> Cc: Holger Assmann <h...@pengutronix.de> >> Signed-off-by: Ahmad Fatoum <a.fat...@pengutronix.de> >> --- >> drivers/iio/adc/stm32-adc.c | 31 +++++++++++++++++++++++++------ >> 1 file changed, 25 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c >> index c067c994dae2..91d9483e1f5f 100644 >> --- a/drivers/iio/adc/stm32-adc.c >> +++ b/drivers/iio/adc/stm32-adc.c >> @@ -1718,7 +1718,7 @@ static void stm32_adc_chan_init_one(struct iio_dev >> *indio_dev, >> } >> } >> >> -static int stm32_adc_chan_of_init(struct iio_dev *indio_dev) >> +static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool >> timestamping) >> { >> struct device_node *node = indio_dev->dev.of_node; >> struct stm32_adc *adc = iio_priv(indio_dev); >> @@ -1766,6 +1766,9 @@ static int stm32_adc_chan_of_init(struct iio_dev >> *indio_dev) >> return -EINVAL; >> } >> >> + if (timestamping) >> + num_channels++; >> + >> channels = devm_kcalloc(&indio_dev->dev, num_channels, >> sizeof(struct iio_chan_spec), GFP_KERNEL); >> if (!channels) >> @@ -1816,6 +1819,19 @@ static int stm32_adc_chan_of_init(struct iio_dev >> *indio_dev) >> stm32_adc_smpr_init(adc, channels[i].channel, smp); >> } >> >> + if (timestamping) { >> + struct iio_chan_spec *timestamp = &channels[scan_index]; >> + >> + timestamp->type = IIO_TIMESTAMP; >> + timestamp->channel = -1; >> + timestamp->scan_index = scan_index; >> + timestamp->scan_type.sign = 's'; >> + timestamp->scan_type.realbits = 64; >> + timestamp->scan_type.storagebits = 64; >> + >> + scan_index++; >> + } >> + >> indio_dev->num_channels = scan_index; >> indio_dev->channels = channels; >> >> @@ -1875,6 +1891,7 @@ static int stm32_adc_probe(struct platform_device >> *pdev) >> struct device *dev = &pdev->dev; >> irqreturn_t (*handler)(int irq, void *p) = NULL; >> struct stm32_adc *adc; >> + bool timestamping = false; >> int ret; >> >> if (!pdev->dev.of_node) >> @@ -1931,16 +1948,18 @@ static int stm32_adc_probe(struct platform_device >> *pdev) >> if (ret < 0) >> return ret; >> >> - ret = stm32_adc_chan_of_init(indio_dev); >> - if (ret < 0) >> - return ret; >> - >> ret = stm32_adc_dma_request(dev, indio_dev); >> if (ret < 0) >> return ret; >> >> - if (!adc->dma_chan) >> + if (!adc->dma_chan) { >> handler = &stm32_adc_trigger_handler; > > Hi Ahmad, > > Just suggesting: maybe add a quick comment to indicate that timestamping > is supported in PIO mode (only), as DMA doesn't fill it into the buffer > (well described in the commit message).
Will do. > >> + timestamping = true; >> + } >> + >> + ret = stm32_adc_chan_of_init(indio_dev, timestamping); >> + if (ret < 0) >> + return ret; > > > DMA resources need to be freed, instead of returning directly here, in > case of error: > > goto err_dma_disable; Ouch, thanks for spotting. Will respin. > > With that fixed, you can add my : > > Acked-by: Fabrice Gasnier <fabrice.gasn...@foss.st.com> Thanks, Ahmad > > Thanks, > > Fabrice > > >> >> ret = iio_triggered_buffer_setup(indio_dev, >> &iio_pollfunc_store_time, handler, > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |