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Diffstat (limited to 'target/linux/brcm2708/patches-4.4/0405-dmaengine-bcm2835-Avoid-splitting-periods-into-very-.patch')
-rw-r--r--target/linux/brcm2708/patches-4.4/0405-dmaengine-bcm2835-Avoid-splitting-periods-into-very-.patch56
1 files changed, 0 insertions, 56 deletions
diff --git a/target/linux/brcm2708/patches-4.4/0405-dmaengine-bcm2835-Avoid-splitting-periods-into-very-.patch b/target/linux/brcm2708/patches-4.4/0405-dmaengine-bcm2835-Avoid-splitting-periods-into-very-.patch
deleted file mode 100644
index 6ee4e29c7c..0000000000
--- a/target/linux/brcm2708/patches-4.4/0405-dmaengine-bcm2835-Avoid-splitting-periods-into-very-.patch
+++ /dev/null
@@ -1,56 +0,0 @@
-From d9f7bbf7d6f175dc2363c027b931d36fb5e091d1 Mon Sep 17 00:00:00 2001
-From: Matthias Reichl <hias@horus.com>
-Date: Wed, 8 Jun 2016 13:09:56 +0200
-Subject: [PATCH] dmaengine: bcm2835: Avoid splitting periods into very small
- chunks
-
-The current cyclic DMA period splitting implementation can generate
-very small chunks at the end of each period. For example a 65536 byte
-period will be split into a 65532 byte chunk and a 4 byte chunk on
-the "lite" DMA channels.
-
-This increases pressure on the RAM controller as the DMA controller
-needs to fetch two control blocks from RAM in quick succession and
-could potentially cause latency issues if the RAM is tied up by other
-devices.
-
-We can easily avoid these situations by distributing the remaining
-length evenly between the last-but-one and the last chunk, making
-sure that split chunks will be at least half the maximum length the
-DMA controller can handle.
-
-This patch checks if the last chunk would be less than half of
-the maximum DMA length and if yes distributes the max len+4...max_len*1.5
-bytes evenly between the last 2 chunks. This results in chunk sizes
-between max_len/2 and max_len*0.75 bytes.
-
-Signed-off-by: Matthias Reichl <hias@horus.com>
-Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
-Tested-by: Clive Messer <clive.messer@digitaldreamtime.co.uk>
----
- drivers/dma/bcm2835-dma.c | 14 ++++++++++++++
- 1 file changed, 14 insertions(+)
-
---- a/drivers/dma/bcm2835-dma.c
-+++ b/drivers/dma/bcm2835-dma.c
-@@ -253,6 +253,20 @@ static void bcm2835_dma_create_cb_set_le
-
- /* have we filled in period_length yet? */
- if (*total_len + control_block->length < period_len) {
-+ /*
-+ * If the next control block is the last in the period
-+ * and it's length would be less than half of max_len
-+ * change it so that both control blocks are (almost)
-+ * equally long. This avoids generating very short
-+ * control blocks (worst case would be 4 bytes) which
-+ * might be problematic. We also have to make sure the
-+ * new length is a multiple of 4 bytes.
-+ */
-+ if (*total_len + control_block->length + max_len / 2 >
-+ period_len) {
-+ control_block->length =
-+ DIV_ROUND_UP(period_len - *total_len, 8) * 4;
-+ }
- /* update number of bytes in this period so far */
- *total_len += control_block->length;
- return;