Am 31.10.2013 13:03, schrieb Mika Westerberg:
> On Thu, Oct 31, 2013 at 01:09:55PM +0200, Mika Westerberg wrote:
>> On Wed, Oct 30, 2013 at 11:14:34PM +0100, Frank Schäfer wrote:
>>> Hmm... try to replace the whole pl2303.c from 3.12 with the one from 3.11.
>>> If it makes no difference, it's not a pl2303 issue.
>> I did that and the 3.11 pl2303.c works (whereas 3.12 doesn't).
>>
>> Can you tell me why do we even want to use this "divisor" based calculation
>> if we can do the same with direct method?
>>
>> I mean why the driver can't do this:
>>
>> 1) Try direct method for *all* chips.
>> 2) If it succeeds, use that value. Then we don't get any difference
>> between actual and set baud rate.
>> 3) If it fails, then and only then use "divisor" based method.
>>
>> I would expect that the above cures my problem and possibly others who
>> might have affected by this regression.
> Something like the patch below.
>
> diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
> index bedf8e47713b..85f3fa4afc81 100644
> --- a/drivers/usb/serial/pl2303.c
> +++ b/drivers/usb/serial/pl2303.c
> @@ -461,11 +461,11 @@ static void pl2303_encode_baudrate(struct tty_struct
> *tty,
> enum pl2303_type type,
> u8 buf[4])
> {
> - int baud;
> + int baud_req, baud;
>
> - baud = tty_get_baud_rate(tty);
> - dev_dbg(&port->dev, "baud requested = %d\n", baud);
> - if (!baud)
> + baud_req = tty_get_baud_rate(tty);
> + dev_dbg(&port->dev, "baud requested = %d\n", baud_req);
> + if (!baud_req)
> return;
> /*
> * There are two methods for setting/encoding the baud rate
> @@ -480,10 +480,10 @@ static void pl2303_encode_baudrate(struct tty_struct
> *tty,
> * the device likely uses the same baud rate generator for both methods
> * so that there is likley no difference.
> */
> - if (type == type_0 || type == type_1 || type == HX_CLONE)
> - baud = pl2303_baudrate_encode_direct(baud, type, buf);
> - else
> - baud = pl2303_baudrate_encode_divisor(baud, type, buf);
> + baud = pl2303_baudrate_encode_direct(baud_req, type, buf);
> + if (baud != baud_req)
> + baud = pl2303_baudrate_encode_divisor(baud_req, type, buf);
> +
That doesn't work.
The direct encoding always succeeds.
But if an unsupported baud rate is set, original chips silently run at
9600 baud and the Chinese clones produce data corruption. :/
Frank
> /* Save resulting baud rate */
> tty_encode_baud_rate(tty, baud, baud);
> dev_dbg(&port->dev, "baud set = %d\n", baud);
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