> > > + u8 buffer[HSC_REG_MEASUREMENT_RD_SIZE]; > > > > This is used for SPI transfers so should be DMA safe. It's not currently. > > Look at how IIO_DMA_MINALIGN is used in other drivers to ensure there is > > no unsafe sharing of cachelines. > > > > On some architectures this is fixed by the stuff that bounces all small transfers > > but I don't think that is universal yet. If you want more info find the talk > > by Wolfram Sang from a few years ago an ELCE on I2C DMA safe buffers. > > that was a nice rabbit hole, thanks for the pointer. :) > > now, based on [2] I will skip explicit i2c dma-related code since my requests > are 4 bytes long. according to the document, any i2c xfer below 8bytes is not > worth the overhead. > > [2] https://www.kernel.org/doc/html/latest/i2c/dma-considerations.html > > > > +static int hsc_spi_probe(struct spi_device *spi) > > > +{ > > > + struct iio_dev *indio_dev; > > > + struct hsc_data *hsc; > > > + struct device *dev = &spi->dev; > > > + > > > + indio_dev = devm_iio_device_alloc(dev, sizeof(*hsc)); > > > + if (!indio_dev) > > > + return -ENOMEM; > > > + > > > + hsc = iio_priv(indio_dev); > > > + hsc->xfer = hsc_spi_xfer; > > > > Also, pass the callback and spi->dev into hsc probe. Easy to use > > a container_of() to get back to the struct spi_device *spi > > I'd rather simply pass along the client struct. > I don't like the fact it has to be a void * The core code has no idea what is in there. At least we constraint it somewhat with a struct device. If you want to use a union of the possible types, that would also be fine. > > > + hsc->client = spi; > > > + > > > + return hsc_probe(indio_dev, &spi->dev, spi_get_device_id(spi)->name, > > > + spi_get_device_id(spi)->driver_data); > > Don't use anything form spi_get_device_id() > > > > Name is a fixed string currently so pass that directly. > > For driver data, there isn't any yet but if there were use > > spi_get_device_match_data() and make sure to provide the data in all the > > id tables. That function will search the firmware ones first then call > > back to the spi specific varient. > > along the way driver_data became redundant, so it was removed from the function > prototype. > > best regards, > peter > >
