aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/video4linux/cx2341x/fw-dma.txt
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/video4linux/cx2341x/fw-dma.txt')
-rw-r--r--Documentation/video4linux/cx2341x/fw-dma.txt16
1 files changed, 9 insertions, 7 deletions
diff --git a/Documentation/video4linux/cx2341x/fw-dma.txt b/Documentation/video4linux/cx2341x/fw-dma.txt
index 8123e262d5b6..be52b6fd1e9a 100644
--- a/Documentation/video4linux/cx2341x/fw-dma.txt
+++ b/Documentation/video4linux/cx2341x/fw-dma.txt
@@ -22,6 +22,8 @@ urged to choose a smaller block size and learn the scatter-gather technique.
22 22
23Mailbox #10 is reserved for DMA transfer information. 23Mailbox #10 is reserved for DMA transfer information.
24 24
25Note: the hardware expects little-endian data ('intel format').
26
25Flow 27Flow
26==== 28====
27 29
@@ -64,7 +66,7 @@ addresses are the physical memory location of the target DMA buffer.
64 66
65Each S-G array element is a struct of three 32-bit words. The first word is 67Each S-G array element is a struct of three 32-bit words. The first word is
66the source address, the second is the destination address. Both take up the 68the source address, the second is the destination address. Both take up the
67entire 32 bits. The lowest 16 bits of the third word is the transfer byte 69entire 32 bits. The lowest 18 bits of the third word is the transfer byte
68count. The high-bit of the third word is the "last" flag. The last-flag tells 70count. The high-bit of the third word is the "last" flag. The last-flag tells
69the card to raise the DMA_DONE interrupt. From hard personal experience, if 71the card to raise the DMA_DONE interrupt. From hard personal experience, if
70you forget to set this bit, the card will still "work" but the stream will 72you forget to set this bit, the card will still "work" but the stream will
@@ -78,8 +80,8 @@ Array Element:
78 80
79- 32-bit Source Address 81- 32-bit Source Address
80- 32-bit Destination Address 82- 32-bit Destination Address
81- 16-bit reserved (high bit is the last flag) 83- 14-bit reserved (high bit is the last flag)
82- 16-bit byte count 84- 18-bit byte count
83 85
84DMA Transfer Status 86DMA Transfer Status
85=================== 87===================
@@ -87,8 +89,8 @@ DMA Transfer Status
87Register 0x0004 holds the DMA Transfer Status: 89Register 0x0004 holds the DMA Transfer Status:
88 90
89Bit 91Bit
904 Scatter-Gather array error
913 DMA write error
922 DMA read error
931 write completed
940 read completed 920 read completed
931 write completed
942 DMA read error
953 DMA write error
964 Scatter-Gather array error