linux/drivers/usb
Frank Schäfer 034d1527ad pl2303: improve the chip type detection/distinction
The driver currently knows about 3 different PL2303 chip types:
The two legacy chip types type_0 and type_1 (PL2303H ?) and the HX
type.
The device distinction is currently completely based on the examination
of the USB descriptors.
During the last years, Prolific has introduced further PL2303 chips,
such as the HXD (HX rev. D), TA (which replaced the X/HX chips), SA,
RA, EA and TB variants.
Unfortunately, all these new chips are currently detected as HX chips,
because they are all using the same bMaxPacketSize0 = 0x40 value in the
USB device descriptor.

At this point it is not clear if these chips are really working with
the driver, there are just some positive indicators (like device
manufacturers claiming Linux support for these devices or commit
8d48fdf689 "correctly handle baudrates above 115200" which should only
be necessary for newer devices, ...)

For a complete support of all devices, we need to distinguish between
them, because they differ in several functional aspects, such  as the
maximum supported baud rate (HXD, TB, EA: 12Mbps, HX, TA: 6Mbps,
RA: 1Mbps, SA: 115.2kbps), handshaking line support, RS422/485 and
GPIO ports support (currently not supported by the driver).
And there might be further differences that we don't know yet.

This patch improves the chip type detection by evaluating the bcdDevice
value of the device descriptor. The values are taken from the
datasheets and are safe to use because manufacturers can't change them:

3.00: X/HX, TA
4.00: HXD, EA, RA, SA
5.00: TB

The rest of the device descriptors is completely identical, so no
further distinction is possible this way.
Anyway, Prolifics "checkChipVersion.exe"-tool is definitely able to
distinguish for example between the X/HX and the TA chips, so there
must be a possibility to improve the distinction further...

Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-08-14 12:12:43 -07:00
..
atm usb: atm: speedtch: be careful with bInterval 2013-07-25 11:49:30 -07:00
c67x00 USB: c67x00: use dev_get_platdata() 2013-07-31 17:28:44 -07:00
chipidea usb: patches for v3.12 merge window 2013-08-13 15:28:01 -07:00
class USB: cdc-wdm: fix race between interrupt handler and tasklet 2013-08-12 15:41:07 -07:00
core usb/hcd: Log error code if reset() fails 2013-08-12 13:13:32 -07:00
dwc3 Merge branch 'nop-phy-rename' into next 2013-08-09 17:31:23 +03:00
early fix build of EHCI debug port code when USB_CHIPIDEA but !USB_EHCI_HCD 2012-11-02 10:13:33 -07:00
gadget usb: patches for v3.12 merge window 2013-08-13 15:28:01 -07:00
host usb: patches for v3.12 merge window 2013-08-13 15:28:01 -07:00
image USB: regroup all depends on USB within an if USB block 2013-04-09 16:49:07 -07:00
misc usb: ehci: Add support for SINGLE_STEP_SET_FEATURE test of EHSET 2013-08-12 13:13:32 -07:00
mon USB: regroup all depends on USB within an if USB block 2013-04-09 16:49:07 -07:00
musb usb: patches for v3.12 merge window 2013-08-13 15:28:01 -07:00
phy usb: patches for v3.12 merge window 2013-08-13 15:28:01 -07:00
renesas_usbhs usb: renesas: use dev_get_platdata() 2013-07-31 17:28:45 -07:00
serial pl2303: improve the chip type detection/distinction 2013-08-14 12:12:43 -07:00
storage USB: storage: Add MicroVault Flash Drive to unusual_devs 2013-07-22 11:29:26 -07:00
wusbcore wusbcore: clean up list locking in urb enqueue 2013-08-12 13:13:33 -07:00
Kconfig usb: Move definition of USB_EHCI_BIG_ENDIAN_MMIO et al. out side of the ifs. 2013-08-12 12:18:38 -07:00
Makefile usb: patches for v3.12 merge window 2013-08-13 15:28:01 -07:00
README
usb-common.c usb: common: introduce of_usb_get_maximum_speed() 2013-07-29 13:56:46 +03:00
usb-skeleton.c USB: usb-skeleton.c: add retry for nonblocking read 2013-07-25 12:01:13 -07:00

README

To understand all the Linux-USB framework, you'll use these resources:

    * This source code.  This is necessarily an evolving work, and
      includes kerneldoc that should help you get a current overview.
      ("make pdfdocs", and then look at "usb.pdf" for host side and
      "gadget.pdf" for peripheral side.)  Also, Documentation/usb has
      more information.

    * The USB 2.0 specification (from www.usb.org), with supplements
      such as those for USB OTG and the various device classes.
      The USB specification has a good overview chapter, and USB
      peripherals conform to the widely known "Chapter 9".

    * Chip specifications for USB controllers.  Examples include
      host controllers (on PCs, servers, and more); peripheral
      controllers (in devices with Linux firmware, like printers or
      cell phones); and hard-wired peripherals like Ethernet adapters.

    * Specifications for other protocols implemented by USB peripheral
      functions.  Some are vendor-specific; others are vendor-neutral
      but just standardized outside of the www.usb.org team.

Here is a list of what each subdirectory here is, and what is contained in
them.

core/		- This is for the core USB host code, including the
		  usbfs files and the hub class driver ("khubd").

host/		- This is for USB host controller drivers.  This
		  includes UHCI, OHCI, EHCI, and others that might
		  be used with more specialized "embedded" systems.

gadget/		- This is for USB peripheral controller drivers and
		  the various gadget drivers which talk to them.


Individual USB driver directories.  A new driver should be added to the
first subdirectory in the list below that it fits into.

image/		- This is for still image drivers, like scanners or
		  digital cameras.
../input/	- This is for any driver that uses the input subsystem,
		  like keyboard, mice, touchscreens, tablets, etc.
../media/	- This is for multimedia drivers, like video cameras,
		  radios, and any other drivers that talk to the v4l
		  subsystem.
../net/		- This is for network drivers.
serial/		- This is for USB to serial drivers.
storage/	- This is for USB mass-storage drivers.
class/		- This is for all USB device drivers that do not fit
		  into any of the above categories, and work for a range
		  of USB Class specified devices. 
misc/		- This is for all USB device drivers that do not fit
		  into any of the above categories.