Re: non-standard baud rates with Prolific 2303 USB-serial

From: Johan Hovold <johan@kernel.org>
To: Charles Yeh <charlesyeh522@gmail.com>
Cc: "Michael G. Katzmann" <michaelk@ieee.org>,
	"Yeh.Charles [葉榮鑫]" <charles-yeh@prolific.com.tw>,
	linux-serial@vger.kernel.org, linux-usb@vger.kernel.org,
	"Joe Abbott" <jabbott@rollanet.org>
Subject: Re: non-standard baud rates with Prolific 2303 USB-serial
Date: Wed, 24 Feb 2021 18:00:53 +0100	[thread overview]
Message-ID: <YDaGRRYrEO5BEJv0@hovoldconsulting.com> (raw)
In-Reply-To: <CAAZvQQ6F=cQ-EhC0kgeTVM3GrtBWR+HfM6UJWj2AEF1NYZ-vAQ@mail.gmail.com>

On Wed, Feb 24, 2021 at 03:34:43PM +0800, Charles Yeh wrote:
> PL2303HXD
>           ===>Device Descriptor<===
> bLength:                           0x12
> bDescriptorType:                   0x01
> bcdUSB:                          0x0110
> bDeviceClass:                      0x00  -> This is an Interface Class
> Defined Device
> bDeviceSubClass:                   0x00
> bDeviceProtocol:                   0x00
> bMaxPacketSize0:                   0x40 = (64) Bytes
> idVendor:                        0x067B = Prolific Technology, Inc.
> idProduct:                       0x2303
> bcdDevice:                       0x0400
> 
> 
> 
> PL2303TA
>           ===>Device Descriptor<===
> bLength:                           0x12
> bDescriptorType:                   0x01
> bcdUSB:                          0x0200
> bDeviceClass:                      0x00  -> This is an Interface Class
> Defined Device
> bDeviceSubClass:                   0x00
> bDeviceProtocol:                   0x00
> bMaxPacketSize0:                   0x40 = (64) Bytes
> idVendor:                        0x067B = Prolific Technology, Inc.
> idProduct:                       0x2303
> bcdDevice:                       0x0300
> 
> 
> PL2303HX(A)/XA ( EOL : PHASED OUT SINCE 2012 )
>           ===>Device Descriptor<===
> bLength:                           0x12
> bDescriptorType:                   0x01
> bcdUSB:                          0x0110
> bDeviceClass:                      0x00  -> This is an Interface Class
> Defined Device
> bDeviceSubClass:                   0x00
> bDeviceProtocol:                   0x00
> bMaxPacketSize0:                   0x40 = (64) Bytes
> idVendor:                        0x067B = Prolific Technology, Inc.
> idProduct:                       0x2303
> bcdDevice:                       0x0300
> 
> 
> You can use the two fields bcdUSB & bcdDevice to distinguish PL2303HXD
> / PL2303TA / PL2303HX(A)/XA

Thanks a lot, Charles, then we know how to detect the TA.

But can you confirm that your PL2303TA works with the current Linux
driver at 110 Bd (and doesn't need the alternate divisor encoding)?

Johan