Re: Commit 8a7bf7510d1f ("USB: serial: pl2303: amend and tighten type detection") broke pl2303 driver for my adapter

On Thu, Jul 29, 2021 at 10:37:00AM -0700, Vasily Khoruzhick wrote:

On Thu, Jul 29, 2021 at 3:02 AM Johan Hovold [off-list ref] wrote:

quoted

On Tue, Jul 27, 2021 at 05:00:20PM -0700, Vasily Khoruzhick wrote:

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My PL2303 adapter isn't working after I upgraded to 5.13.

quoted

Thanks for the report. Can you please post the output of lsusb -v for
this device?

Here it is:

Bus 001 Device 024: ID 067b:23c3 Prolific Technology, Inc. USB-Serial
Controller
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            0
  bDeviceSubClass         0
  bDeviceProtocol         0
  bMaxPacketSize0        64
  idVendor           0x067b Prolific Technology, Inc.
  idProduct          0x23c3
  bcdDevice            3.05

Thanks. Based on the above it looks like either a TA using the default
GT idProduct and new subminor release number (3.05), or it's a GT with
an undocumented release number (the datasheet says it should be 1.00).

  iManufacturer           1 Prolific Technology Inc.
  iProduct                2 USB-Serial Controller
  iSerial                 3 CMA>b103Y23
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength       0x0027
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0
    bmAttributes         0xa0
      (Bus Powered)
      Remote Wakeup
    MaxPower              100mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           3
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      0
      bInterfaceProtocol      0
      iInterface              0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x000a  1x 10 bytes
        bInterval               1
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x02  EP 2 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x83  EP 3 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval               0

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Any ideas on how to fix it properly? Should I send a patch that
handles bcdDevice == 0x305 and returns TYPE_HX for it from
pl2303_detect_type()?

The device id indicates that this is in fact a PL2303GT so we may need
to amend the HXN type detection.

What's the difference between HX and HXN?

The HXN type, or rather G-series, uses a different protocol from the
older types and would not work at all unless detected correctly.

Could you try applying the patch below and check the log for that
pl2303_supports_hx_status() printk? If it is indeed a GT then this
should also make the device work again.

Johan


From 4e964bc27a02bc37446caf7fcfb796aed6666830 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Fri, 30 Jul 2021 14:35:24 +0200
Subject: [PATCH] USB: serial: pl2303: add type instrumentation

---
 drivers/usb/serial/pl2303.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index 2f2f5047452b..8ef159473504 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c

@@ -394,6 +394,8 @@ static bool pl2303_supports_hx_status(struct usb_serial *serial)
 			VENDOR_READ_REQUEST_TYPE, PL2303_READ_TYPE_HX_STATUS,
 			0, &buf, 1, 100, GFP_KERNEL);
 
+	dev_info(&serial->interface->dev, "%s - ret = %d\n", __func__, ret);
+
 	return ret == 0;
 }
 

@@ -420,6 +422,7 @@ static int pl2303_detect_type(struct usb_serial *serial)
 
 	switch (bcdDevice) {
 	case 0x100:
+	case 0x305:
 		/*
 		 * Assume it's an HXN-type if the device doesn't support the old read
 		 * request value.

-- 
2.31.1