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USB: serial: pl2303: account for deficits of clones

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There are apparently incomplete clones of the HXD type chip in use.
Those return -EPIPE on GET_LINE_REQUEST and BREAK_REQUEST. Avoid
flooding the kernel log with those errors. Detect them during startup
and then use the line_settings cache instead of GET_LINE_REQUEST. Signal
missing break support via -ENOTTY.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
[ johan: fix macro prefix, drop oom error message ]
Signed-off-by: Johan Hovold <johan@kernel.org>
This commit is contained in:
Jan Kiszka 2024-09-12 10:37:39 +02:00 committed by Johan Hovold
parent 59b723cd2a
commit 40827729cf
1 changed files with 37 additions and 1 deletions
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38
drivers/usb/serial/pl2303.c
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@ -31,6 +31,7 @@
#define PL2303_QUIRK_UART_STATE_IDX0 BIT(0)
#define PL2303_QUIRK_LEGACY BIT(1)
#define PL2303_QUIRK_ENDPOINT_HACK BIT(2)
#define PL2303_QUIRK_NO_BREAK_GETLINE BIT(3)
static const struct usb_device_id id_table[] = {
{ USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID),
@ -467,6 +468,25 @@ static int pl2303_detect_type(struct usb_serial *serial)
return -ENODEV;
}
static bool pl2303_is_hxd_clone(struct usb_serial *serial)
{
struct usb_device *udev = serial->dev;
unsigned char *buf;
int ret;
buf = kmalloc(7, GFP_KERNEL);
if (!buf)
return false;
ret = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
GET_LINE_REQUEST, GET_LINE_REQUEST_TYPE,
0, 0, buf, 7, 100);
kfree(buf);
return ret == -EPIPE;
}
static int pl2303_startup(struct usb_serial *serial)
{
struct pl2303_serial_private *spriv;
@ -489,6 +509,9 @@ static int pl2303_startup(struct usb_serial *serial)
spriv->quirks = (unsigned long)usb_get_serial_data(serial);
spriv->quirks |= spriv->type->quirks;
if (type == TYPE_HXD && pl2303_is_hxd_clone(serial))
spriv->quirks |= PL2303_QUIRK_NO_BREAK_GETLINE;
usb_set_serial_data(serial, spriv);
if (type != TYPE_HXN) {
@ -725,9 +748,18 @@ static void pl2303_encode_baud_rate(struct tty_struct *tty,
static int pl2303_get_line_request(struct usb_serial_port *port,
unsigned char buf[7])
{
struct usb_device *udev = port->serial->dev;
struct usb_serial *serial = port->serial;
struct pl2303_serial_private *spriv = usb_get_serial_data(serial);
struct usb_device *udev = serial->dev;
int ret;
if (spriv->quirks & PL2303_QUIRK_NO_BREAK_GETLINE) {
struct pl2303_private *priv = usb_get_serial_port_data(port);
memcpy(buf, priv->line_settings, 7);
return 0;
}
ret = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
GET_LINE_REQUEST, GET_LINE_REQUEST_TYPE,
0, 0, buf, 7, 100);
@ -1064,9 +1096,13 @@ static int pl2303_carrier_raised(struct usb_serial_port *port)
static int pl2303_set_break(struct usb_serial_port *port, bool enable)
{
struct usb_serial *serial = port->serial;
struct pl2303_serial_private *spriv = usb_get_serial_data(serial);
u16 state;
int result;
if (spriv->quirks & PL2303_QUIRK_NO_BREAK_GETLINE)
return -ENOTTY;
if (enable)
state = BREAK_ON;
else