On Thu, 28 Mar 2024 16:16:59 -0500 David Lechner <dlechner@xxxxxxxxxxxx> wrote: > This modifies the ad7944 driver to use spi_optimize_message() to reduce > CPU usage and increase the max sample rate by avoiding repeating > validation of the spi message on each transfer. > > Signed-off-by: David Lechner <dlechner@xxxxxxxxxxxx> Applied to the togreg branch of iio.git and pushed out as testing. Thanks, Jonathan > --- > Changes in v2: > - Fix wrong array index in ad7944_3wire_cs_mode_init_msg() > - Fixed wrong number of xfers in ad7944_4wire_mode_init_msg() > - Link to v1: https://lore.kernel.org/r/20240325-ad7944-spi-optimize-message-v1-1-cded69b9e27f@xxxxxxxxxxxx > --- > drivers/iio/adc/ad7944.c | 177 +++++++++++++++++++++++++++-------------------- > 1 file changed, 103 insertions(+), 74 deletions(-) > > diff --git a/drivers/iio/adc/ad7944.c b/drivers/iio/adc/ad7944.c > index 261a3f645fd8..e09ab0c842d3 100644 > --- a/drivers/iio/adc/ad7944.c > +++ b/drivers/iio/adc/ad7944.c > @@ -51,6 +51,8 @@ static const char * const ad7944_spi_modes[] = { > struct ad7944_adc { > struct spi_device *spi; > enum ad7944_spi_mode spi_mode; > + struct spi_transfer xfers[3]; > + struct spi_message msg; > /* Chip-specific timing specifications. */ > const struct ad7944_timing_spec *timing_spec; > /* GPIO connected to CNV pin. */ > @@ -130,6 +132,88 @@ AD7944_DEFINE_CHIP_INFO(ad7985, ad7944, 16, 0); > /* fully differential */ > AD7944_DEFINE_CHIP_INFO(ad7986, ad7986, 18, 1); > > +static void ad7944_unoptimize_msg(void *msg) > +{ > + spi_unoptimize_message(msg); > +} > + > +static int ad7944_3wire_cs_mode_init_msg(struct device *dev, struct ad7944_adc *adc, > + const struct iio_chan_spec *chan) > +{ > + unsigned int t_conv_ns = adc->always_turbo ? adc->timing_spec->turbo_conv_ns > + : adc->timing_spec->conv_ns; > + struct spi_transfer *xfers = adc->xfers; > + int ret; > + > + /* > + * NB: can get better performance from some SPI controllers if we use > + * the same bits_per_word in every transfer. > + */ > + xfers[0].bits_per_word = chan->scan_type.realbits; > + /* > + * CS is tied to CNV and we need a low to high transition to start the > + * conversion, so place CNV low for t_QUIET to prepare for this. > + */ > + xfers[0].delay.value = T_QUIET_NS; > + xfers[0].delay.unit = SPI_DELAY_UNIT_NSECS; > + > + /* > + * CS has to be high for full conversion time to avoid triggering the > + * busy indication. > + */ > + xfers[1].cs_off = 1; > + xfers[1].delay.value = t_conv_ns; > + xfers[1].delay.unit = SPI_DELAY_UNIT_NSECS; > + xfers[1].bits_per_word = chan->scan_type.realbits; > + > + /* Then we can read the data during the acquisition phase */ > + xfers[2].rx_buf = &adc->sample.raw; > + xfers[2].len = BITS_TO_BYTES(chan->scan_type.storagebits); > + xfers[2].bits_per_word = chan->scan_type.realbits; > + > + spi_message_init_with_transfers(&adc->msg, xfers, 3); > + > + ret = spi_optimize_message(adc->spi, &adc->msg); > + if (ret) > + return ret; > + > + return devm_add_action_or_reset(dev, ad7944_unoptimize_msg, &adc->msg); > +} > + > +static int ad7944_4wire_mode_init_msg(struct device *dev, struct ad7944_adc *adc, > + const struct iio_chan_spec *chan) > +{ > + unsigned int t_conv_ns = adc->always_turbo ? adc->timing_spec->turbo_conv_ns > + : adc->timing_spec->conv_ns; > + struct spi_transfer *xfers = adc->xfers; > + int ret; > + > + /* > + * NB: can get better performance from some SPI controllers if we use > + * the same bits_per_word in every transfer. > + */ > + xfers[0].bits_per_word = chan->scan_type.realbits; > + /* > + * CS has to be high for full conversion time to avoid triggering the > + * busy indication. > + */ > + xfers[0].cs_off = 1; > + xfers[0].delay.value = t_conv_ns; > + xfers[0].delay.unit = SPI_DELAY_UNIT_NSECS; > + > + xfers[1].rx_buf = &adc->sample.raw; > + xfers[1].len = BITS_TO_BYTES(chan->scan_type.storagebits); > + xfers[1].bits_per_word = chan->scan_type.realbits; > + > + spi_message_init_with_transfers(&adc->msg, xfers, 2); > + > + ret = spi_optimize_message(adc->spi, &adc->msg); > + if (ret) > + return ret; > + > + return devm_add_action_or_reset(dev, ad7944_unoptimize_msg, &adc->msg); > +} > + > /* > * ad7944_3wire_cs_mode_conversion - Perform a 3-wire CS mode conversion and > * acquisition > @@ -145,48 +229,7 @@ AD7944_DEFINE_CHIP_INFO(ad7986, ad7986, 18, 1); > static int ad7944_3wire_cs_mode_conversion(struct ad7944_adc *adc, > const struct iio_chan_spec *chan) > { > - unsigned int t_conv_ns = adc->always_turbo ? adc->timing_spec->turbo_conv_ns > - : adc->timing_spec->conv_ns; > - struct spi_transfer xfers[] = { > - { > - /* > - * NB: can get better performance from some SPI > - * controllers if we use the same bits_per_word > - * in every transfer. > - */ > - .bits_per_word = chan->scan_type.realbits, > - /* > - * CS is tied to CNV and we need a low to high > - * transition to start the conversion, so place CNV > - * low for t_QUIET to prepare for this. > - */ > - .delay = { > - .value = T_QUIET_NS, > - .unit = SPI_DELAY_UNIT_NSECS, > - }, > - > - }, > - { > - .bits_per_word = chan->scan_type.realbits, > - /* > - * CS has to be high for full conversion time to avoid > - * triggering the busy indication. > - */ > - .cs_off = 1, > - .delay = { > - .value = t_conv_ns, > - .unit = SPI_DELAY_UNIT_NSECS, > - }, > - }, > - { > - /* Then we can read the data during the acquisition phase */ > - .rx_buf = &adc->sample.raw, > - .len = BITS_TO_BYTES(chan->scan_type.storagebits), > - .bits_per_word = chan->scan_type.realbits, > - }, > - }; > - > - return spi_sync_transfer(adc->spi, xfers, ARRAY_SIZE(xfers)); > + return spi_sync(adc->spi, &adc->msg); > } > > /* > @@ -200,33 +243,6 @@ static int ad7944_3wire_cs_mode_conversion(struct ad7944_adc *adc, > static int ad7944_4wire_mode_conversion(struct ad7944_adc *adc, > const struct iio_chan_spec *chan) > { > - unsigned int t_conv_ns = adc->always_turbo ? adc->timing_spec->turbo_conv_ns > - : adc->timing_spec->conv_ns; > - struct spi_transfer xfers[] = { > - { > - /* > - * NB: can get better performance from some SPI > - * controllers if we use the same bits_per_word > - * in every transfer. > - */ > - .bits_per_word = chan->scan_type.realbits, > - /* > - * CS has to be high for full conversion time to avoid > - * triggering the busy indication. > - */ > - .cs_off = 1, > - .delay = { > - .value = t_conv_ns, > - .unit = SPI_DELAY_UNIT_NSECS, > - }, > - > - }, > - { > - .rx_buf = &adc->sample.raw, > - .len = BITS_TO_BYTES(chan->scan_type.storagebits), > - .bits_per_word = chan->scan_type.realbits, > - }, > - }; > int ret; > > /* > @@ -234,7 +250,7 @@ static int ad7944_4wire_mode_conversion(struct ad7944_adc *adc, > * and acquisition process. > */ > gpiod_set_value_cansleep(adc->cnv, 1); > - ret = spi_sync_transfer(adc->spi, xfers, ARRAY_SIZE(xfers)); > + ret = spi_sync(adc->spi, &adc->msg); > gpiod_set_value_cansleep(adc->cnv, 0); > > return ret; > @@ -395,10 +411,6 @@ static int ad7944_probe(struct spi_device *spi) > adc->spi_mode = ret; > } > > - if (adc->spi_mode == AD7944_SPI_MODE_CHAIN) > - return dev_err_probe(dev, -EINVAL, > - "chain mode is not implemented\n"); > - > /* > * Some chips use unusual word sizes, so check now instead of waiting > * for the first xfer. > @@ -491,6 +503,23 @@ static int ad7944_probe(struct spi_device *spi) > return dev_err_probe(dev, -EINVAL, > "cannot have both chain mode and always turbo\n"); > > + switch (adc->spi_mode) { > + case AD7944_SPI_MODE_DEFAULT: > + ret = ad7944_4wire_mode_init_msg(dev, adc, &chip_info->channels[0]); > + if (ret) > + return ret; > + > + break; > + case AD7944_SPI_MODE_SINGLE: > + ret = ad7944_3wire_cs_mode_init_msg(dev, adc, &chip_info->channels[0]); > + if (ret) > + return ret; > + > + break; > + case AD7944_SPI_MODE_CHAIN: > + return dev_err_probe(dev, -EINVAL, "chain mode is not implemented\n"); > + } > + > indio_dev->name = chip_info->name; > indio_dev->modes = INDIO_DIRECT_MODE; > indio_dev->info = &ad7944_iio_info; > > --- > base-commit: 526f7f17b651c78ead26fea7cea20948c00e47a5 > change-id: 20240325-ad7944-spi-optimize-message-82debaa2a5a7 > > Best regards,
