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USB: serial: ch341: backports to 5.15

PATCH Applied Johan Hovold 2 participants 5 messages Sep 6, 2022 Stable branch

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Johan Hovold

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#0 lore raw

cover USB: serial: ch341: backports to 5.15

Here are backports of two patches that failed to apply to 5.15 and older stable trees.

Only the first one actually needed to have some context adjusted.

Johan

Johan Hovold (2):
USB: serial: ch341: fix lost character on LCR updates
USB: serial: ch341: fix disabled rx timer on older devices

 drivers/usb/serial/ch341.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)
Signature · 1 line
2.35.1
author
#1 lore raw

PATCH 1/2 USB: serial: ch341: fix lost character on LCR updates

commit 8e83622ae7ca481c76c8fd9579877f6abae64ca2 upstream.

Disable LCR updates for pre-0x30 devices which use a different (unknown) protocol for line control and where the current register write causes the next received character to be lost.

Note that updating LCR using the INIT command has no effect on these devices either.

Reported-by Jonathan Woithe <[email protected]>
Tested-by Jonathan Woithe <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Fixes 4e46c410e050 ("USB: serial: ch341: reinitialize chip on reconfiguration")
Fixes 55fa15b5987d ("USB: serial: ch341: fix baud rate and line-control handling")
Cc [email protected] # 4.10
Signed-off-by Johan Hovold <[email protected]>
[ johan: adjust context to 5.15 ]
Signed-off-by Johan Hovold <[email protected]>
---
 drivers/usb/serial/ch341.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)
drivers/usb/serial/ch341.c +9 -1
index b5a1864e9cfd..b787533aec64 100644
@@ -97,7 +97,10 @@ struct ch341_private {
 	u8 mcr;
 	u8 msr;
 	u8 lcr;
+
 	unsigned long quirks;
+	u8 version;
+
 	unsigned long break_end;
 };
 

@@ -271,6 +274,9 @@ static int ch341_set_baudrate_lcr(struct usb_device *dev,
 	 * (stop bits, parity and word length). Version 0x30 and above use
 	 * CH341_REG_LCR only and CH341_REG_LCR2 is always set to zero.
 	 */
+	if (priv->version < 0x30)
+		return 0;
+
 	r = ch341_control_out(dev, CH341_REQ_WRITE_REG,
 			      CH341_REG_LCR2 << 8 | CH341_REG_LCR, lcr);
 	if (r)

@@ -323,7 +329,9 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 	r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size);
 	if (r < 0)
 		goto out;
-	dev_dbg(&dev->dev, "Chip version: 0x%02x\n", buffer[0]);
+
+	priv->version = buffer[0];
+	dev_dbg(&dev->dev, "Chip version: 0x%02x\n", priv->version);
 
 	r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0);
 	if (r < 0)
Signature · 1 line
2.35.1
author
#2 lore raw

PATCH 2/2 USB: serial: ch341: fix disabled rx timer on older devices

In reply to Johan Hovold

commit 41ca302a697b64a3dab4676e01d0d11bb184737d upstream.

At least one older CH341 appears to have the RX timer enable bit inverted so that setting it disables the RX timer and prevents the FIFO from emptying until it is full.

Only set the RX timer enable bit for devices with version newer than 0x27 (even though this probably affects all pre-0x30 devices).

Reported-by Jonathan Woithe <[email protected]>
Tested-by Jonathan Woithe <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Fixes 4e46c410e050 ("USB: serial: ch341: reinitialize chip on reconfiguration")
Cc [email protected] # 4.10
Signed-off-by Johan Hovold <[email protected]>
---
 drivers/usb/serial/ch341.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
drivers/usb/serial/ch341.c +5 -1
index b787533aec64..752daa952abd 100644
@@ -259,8 +259,12 @@ static int ch341_set_baudrate_lcr(struct usb_device *dev,
 	/*
 	 * CH341A buffers data until a full endpoint-size packet (32 bytes)
 	 * has been received unless bit 7 is set.
+	 *
+	 * At least one device with version 0x27 appears to have this bit
+	 * inverted.
 	 */
-	val |= BIT(7);
+	if (priv->version > 0x27)
+		val |= BIT(7);
 
 	r = ch341_control_out(dev, CH341_REQ_WRITE_REG,
 			      CH341_REG_DIVISOR << 8 | CH341_REG_PRESCALER,
Signature · 1 line
2.35.1
maintainer Applied
#3 lore raw
In reply to Johan Hovold
Quoted 4 lines · Johan Hovold

Here are backports of two patches that failed to apply to 5.15 and older stable trees.

Only the first one actually needed to have some context adjusted.

Applied to 5.10.y and 5.15.y. didn't apply to anything older, odds are no one cares about this driver for those kernels anyway :)

thanks,

greg k-h

author
#4 lore raw
Quoted 8 lines · Greg Kroah-Hartman
Quoted 4 lines · Johan Hovold

Here are backports of two patches that failed to apply to 5.15 and older stable trees.

Only the first one actually needed to have some context adjusted.

Applied to 5.10.y and 5.15.y. didn't apply to anything older, odds are no one cares about this driver for those kernels anyway :)

True. But now backported for "completeness". :)

Johan