The latency timer was introduced with the FT232BM and FT245BM chips. Do
not bother attempting to read or write it for older chip versions.
Signed-off-by: Ian Abbott <abbo...@mev.co.uk>
---
v2:
- No change.
---
drivers/usb/serial/ftdi_sio.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index c540de15aad2..72314734dfd0 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1406,6 +1406,9 @@ static int write_latency_timer(struct usb_serial_port
*port)
int rv;
int l = priv->latency;
+ if (priv->chip_type == SIO || priv->chip_type == FT8U232AM)
+ return -EINVAL;
+
if (priv->flags & ASYNC_LOW_LATENCY)
l = 1;
@@ -1429,6 +1432,9 @@ static int read_latency_timer(struct usb_serial_port
*port)
unsigned char *buf;
int rv;
+ if (priv->chip_type == SIO || priv->chip_type == FT8U232AM)
+ return -EINVAL;
+
buf = kmalloc(1, GFP_KERNEL);
if (!buf)
return -ENOMEM;
--
2.11.0
--
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