From 2dea7cd7287781cd4bfd0167dba423e0f486ef61 Mon Sep 17 00:00:00 2001 From: Ian Abbott Date: Wed, 8 Mar 2017 16:02:57 +0000 Subject: [PATCH] USB: serial: ftdi_sio: don't access latency timer on old chips 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 Signed-off-by: Johan Hovold --- 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; -- 2.39.2