Patch "iio: adis16400: Fix burst mode" has been added to the 4.0-stable tree

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

iio: adis16400: Fix burst mode

to the 4.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:

     iio-adis16400-fix-burst-mode.patch

and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Paul Cercueil <[email protected]>
Date: Fri, 15 May 2015 17:18:37 +0200
Subject: iio: adis16400: Fix burst mode

From: Paul Cercueil <[email protected]>

commit 9df560350c90f3d3909fe653399b3584c9a17b61 upstream.

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.

---
 drivers/iio/imu/adis16400_buffer.c |   16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

@@ -18,7 +18,8 @@ int adis16400_update_scan_mode(struct ii
 {
 	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 ii
 	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);

Patches currently in stable-queue which might be from [email protected] are

queue-4.0/iio-adis16400-compute-the-scan-mask-from-channel-indices.patch queue-4.0/iio-adis16400-fix-burst-mode.patch queue-4.0/iio-adis16400-use-channel-indices-for-the-two-voltage-channels.patch --
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