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

[Johan Hovold <johan@kernel.org>]

On Thu, Jul 29, 2021 at 10:37:00AM -0700, Vasily Khoruzhick wrote:
> On Thu, Jul 29, 2021 at 3:02 AM Johan Hovold <johan@kernel.org> wrote:
> > On Tue, Jul 27, 2021 at 05:00:20PM -0700, Vasily Khoruzhick wrote:

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

> > 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
> 
> > > 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