My overall understanding [1] is that devm_ allocations will require an extra 16 bytes at the beginning of the allocated buffer to store information about the managing device, this shifts a little bit the buffer which may then not be fully aligned on cache lines, disqualifying them for being suitable for DMA. Let's switch to a regular kmalloc based allocator to ensure st->buffer is DMA-able, as required by the IIO subsystem. [1] https://linux-arm-kernel.infradead.narkive.com/vyJqy0RQ/question-devm-kmalloc-for-dma Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx> --- drivers/iio/adc/max1027.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c index f27044324141..1167d50c1d67 100644 --- a/drivers/iio/adc/max1027.c +++ b/drivers/iio/adc/max1027.c @@ -438,9 +438,7 @@ static int max1027_probe(struct spi_device *spi) indio_dev->num_channels = st->info->num_channels; indio_dev->available_scan_masks = st->info->available_scan_masks; - st->buffer = devm_kmalloc_array(&indio_dev->dev, - indio_dev->num_channels, 2, - GFP_KERNEL); + st->buffer = kmalloc_array(indio_dev->num_channels, 2, GFP_KERNEL); if (!st->buffer) return -ENOMEM; @@ -451,7 +449,7 @@ static int max1027_probe(struct spi_device *spi) NULL); if (ret < 0) { dev_err(&indio_dev->dev, "Failed to setup buffer\n"); - return ret; + goto free_buffer; } st->trig = devm_iio_trigger_alloc(&spi->dev, "%s-trigger", @@ -460,7 +458,7 @@ static int max1027_probe(struct spi_device *spi) ret = -ENOMEM; dev_err(&indio_dev->dev, "Failed to allocate iio trigger\n"); - return ret; + goto free_buffer; } st->trig->ops = &max1027_trigger_ops; @@ -470,7 +468,7 @@ static int max1027_probe(struct spi_device *spi) if (ret < 0) { dev_err(&indio_dev->dev, "Failed to register iio trigger\n"); - return ret; + goto free_buffer; } ret = devm_request_threaded_irq(&spi->dev, spi->irq, @@ -481,7 +479,7 @@ static int max1027_probe(struct spi_device *spi) st->trig); if (ret < 0) { dev_err(&indio_dev->dev, "Failed to allocate IRQ.\n"); - return ret; + goto free_buffer; } } @@ -490,7 +488,7 @@ static int max1027_probe(struct spi_device *spi) ret = spi_write(st->spi, &st->reg, 1); if (ret < 0) { dev_err(&indio_dev->dev, "Failed to reset the ADC\n"); - return ret; + goto free_buffer; } /* Disable averaging */ @@ -498,10 +496,15 @@ static int max1027_probe(struct spi_device *spi) ret = spi_write(st->spi, &st->reg, 1); if (ret < 0) { dev_err(&indio_dev->dev, "Failed to configure averaging register\n"); - return ret; + goto free_buffer; } return devm_iio_device_register(&spi->dev, indio_dev); + +free_buffer: + kfree(st->buffer); + + return ret; } static struct spi_driver max1027_driver = { -- 2.27.0
