On Mon, 27 May 2024 20:37:59 +0200 Vasileios Amoiridis <vassilisamir@xxxxxxxxx> wrote: > Calibration data are located in contiguous-ish registers > inside the chip. For that reason we can use bulk reads as is > done as well in the BME68x Sensor API [1]. > > The arrays that are used for reading the data out of the sensor > are located inside DMA safe buffer. See below. I think in this case that isn't necessary. However it's a quirk of how the custom regmap works. Whilst we can't rely on regmap core spi implementations continuing to bounce buffer, we can rely on one local to our particular driver. > > [1]: https://github.com/boschsensortec/BME68x_SensorAPI/blob/v4.4.8/bme68x.c#L1769 > Signed-off-by: Vasileios Amoiridis <vassilisamir@xxxxxxxxx> > diff --git a/drivers/iio/chemical/bme680_core.c b/drivers/iio/chemical/bme680_core.c > index 681f271f9b06..ed4cdb4d64af 100644 > --- a/drivers/iio/chemical/bme680_core.c > +++ b/drivers/iio/chemical/bme680_core.c > + > struct bme680_calib { > u16 par_t1; > s16 par_t2; > @@ -64,6 +109,16 @@ struct bme680_data { > * and humidity compensation calculations. > */ > s32 t_fine; > + > + /* > + * DMA (thus cache coherency maintenance) may require the > + * transfer buffers to live in their own cache lines. > + */ > + union { > + u8 bme680_cal_buf_1[BME680_CALIB_RANGE_1_LEN]; > + u8 bme680_cal_buf_2[BME680_CALIB_RANGE_2_LEN]; > + u8 bme680_cal_buf_3[BME680_CALIB_RANGE_3_LEN]; > + } __aligned(IIO_DMA_MINALIGN); Ah! I should have read ahead. I don't think you need this alignment forcing because bme680_regmap_spi_read uses spi_write_then_read() which always bounces the data. > }; > > static const struct regmap_range bme680_volatile_ranges[] = { > @@ -112,217 +167,73 @@ static int bme680_read_calib(struct bme680_data *data, > struct bme680_calib *calib) > { > + calib->par_h3 = data->bme680_cal_buf_2[H3]; > + calib->par_h4 = data->bme680_cal_buf_2[H4]; > + calib->par_h5 = data->bme680_cal_buf_2[H5]; > + calib->par_h6 = data->bme680_cal_buf_2[H6]; > + calib->par_h7 = data->bme680_cal_buf_2[H7]; > + calib->par_t1 = get_unaligned_le16(&data->bme680_cal_buf_2[T1_LSB]); > + calib->par_gh2 = get_unaligned_le16(&data->bme680_cal_buf_2[GH2_LSB]); > + calib->par_gh1 = data->bme680_cal_buf_2[GH1]; > + calib->par_gh3 = data->bme680_cal_buf_2[GH3]; > > - ret = regmap_read(data->regmap, BME680_H7_REG, &tmp); > + ret = regmap_bulk_read(data->regmap, BME680_REG_RES_HEAT_VAL, > + &data->bme680_cal_buf_3[0], This one is always debated, but personally I'd prefer data->bme680_cal_buf_3, for cases like this. Up to you though. > + sizeof(data->bme680_cal_buf_3)); > if (ret < 0) { > - dev_err(dev, "failed to read BME680_H7_REG\n"); > + dev_err(dev, "failed to read 3rd set of calib data;\n"); > return ret; > }
