Hello.
On 27-07-2011 8:06, Greg Kroah-Hartman wrote:
From: Michał Sroczyński<msroczyn@xxxxxxxxx>
PL2303: correctly handle baudrates above 115200
Haven't seen this patch before, so have to comment now.
Signed-off-by: Michal Sroczynski<msroczyn@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman<gregkh@xxxxxxx>
---
drivers/usb/serial/pl2303.c | 26 ++++++++++++++++++++++----
1 files changed, 22 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index 30461fc..ee28115 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -342,10 +342,28 @@ static void pl2303_set_termios(struct tty_struct *tty,
baud = 6000000;
}
dbg("%s - baud set = %d", __func__, baud);
- buf[0] = baud & 0xff;
- buf[1] = (baud >> 8) & 0xff;
- buf[2] = (baud >> 16) & 0xff;
- buf[3] = (baud >> 24) & 0xff;
+ if (baud <= 115200) {
+ buf[0] = baud & 0xff;
+ buf[1] = (baud >> 8) & 0xff;
+ buf[2] = (baud >> 16) & 0xff;
+ buf[3] = (baud >> 24) & 0xff;
+ } else {
+ /* apparently the formula for higher speeds is:
+ * baudrate = 12M * 32 / (2^buf[1]) / buf[0]
+ */
+ unsigned tmp = 12*1000*1000*32 / baud;
+ buf[3] = 0x80;
+ buf[2] = 0;
+ buf[1] = (tmp >= 256);
+ while (tmp >= 256) {
+ tmp>>= 2;
+ buf[1]<<= 1;
+ }
+ if (tmp > 256) {
This will never be true due to the *while* loop above. Also, {} are not
needed.
+ tmp %= 256;
+ }
+ buf[0] = tmp;
+ }
}
/* For reference buf[4]=0 is 1 stop bits */
WBR, Sergei
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