patch "iio: adis16400: Fix burst mode" added to staging-linus

patch "iio: adis16400: Fix burst mode" added to staging-linus

[gregkh]

This is a note to let you know that I've just added the patch titled

    iio: adis16400: Fix burst mode

to my staging git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 9df560350c90f3d3909fe653399b3584c9a17b61 Mon Sep 17 00:00:00 2001
From: Paul Cercueil <paul.cercueil@analog.com>
Date: Fri, 15 May 2015 17:18:37 +0200
Subject: iio: adis16400: Fix burst mode

There are a few issues with the burst mode support. For one we don't setup
the rx buffer, so the buffer will never be filled and all samples will read
as the zero. Furthermore the tx buffer has the wrong type, which means the
driver sends the wrong command and not the right data is returned.

The final issue is that in burst mode all channels are transferred. Hence
the length of the transfer length should be the number of hardware
channels * 2 bytes. Currently the driver uses indio_dev->scan_bytes for
this. But if the timestamp channel is enabled the scan_bytes will be larger
than the burst length. Fix this by just calculating the burst length based
on the number of hardware channels.

Signed-off-by: Paul Cercueil <paul.cercueil@analog.com>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Fixes: 5eda3550a3cc ("staging:iio:adis16400: Preallocate transfer message")
Cc: <stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
---
 drivers/iio/imu/adis16400_buffer.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/iio/imu/adis16400_buffer.c b/drivers/iio/imu/adis16400_buffer.c
index 6e727ffe5262..629ae84d4e62 100644
--- a/drivers/iio/imu/adis16400_buffer.c
+++ b/drivers/iio/imu/adis16400_buffer.c
@@ -18,7 +18,8 @@ int adis16400_update_scan_mode(struct iio_dev *indio_dev,
 {
 	struct adis16400_state *st = iio_priv(indio_dev);
 	struct adis *adis = &st->adis;
-	uint16_t *tx;
+	unsigned int burst_length;
+	u8 *tx;
 
 	if (st->variant->flags & ADIS16400_NO_BURST)
 		return adis_update_scan_mode(indio_dev, scan_mask);
@@ -26,26 +27,27 @@ int adis16400_update_scan_mode(struct iio_dev *indio_dev,
 	kfree(adis->xfer);
 	kfree(adis->buffer);
 
+	/* All but the timestamp channel */
+	burst_length = (indio_dev->num_channels - 1) * sizeof(u16);
+
 	adis->xfer = kcalloc(2, sizeof(*adis->xfer), GFP_KERNEL);
 	if (!adis->xfer)
 		return -ENOMEM;
 
-	adis->buffer = kzalloc(indio_dev->scan_bytes + sizeof(u16),
-		GFP_KERNEL);
+	adis->buffer = kzalloc(burst_length + sizeof(u16), GFP_KERNEL);
 	if (!adis->buffer)
 		return -ENOMEM;
 
-	tx = adis->buffer + indio_dev->scan_bytes;
-
+	tx = adis->buffer + burst_length;
 	tx[0] = ADIS_READ_REG(ADIS16400_GLOB_CMD);
 	tx[1] = 0;
 
 	adis->xfer[0].tx_buf = tx;
 	adis->xfer[0].bits_per_word = 8;
 	adis->xfer[0].len = 2;
-	adis->xfer[1].tx_buf = tx;
+	adis->xfer[1].rx_buf = adis->buffer;
 	adis->xfer[1].bits_per_word = 8;
-	adis->xfer[1].len = indio_dev->scan_bytes;
+	adis->xfer[1].len = burst_length;
 
 	spi_message_init(&adis->msg);
 	spi_message_add_tail(&adis->xfer[0], &adis->msg);
-- 
2.4.1