Messages in this thread | | | Date | Wed, 28 Oct 2015 09:51:26 +0100 | From | Johan Hovold <> | Subject | Re: [PATCH v4 3/3] USB: serial: cp210x: Workaround cp2108 GET_LINE_CTL bug |
| |
On Tue, Oct 27, 2015 at 04:53:34PM -0500, Konstantin Shkolnyy wrote: > cp2108 GET_LINE_CTL returns the 16-bit value with the 2 bytes swapped. > However, SET_LINE_CTL functions properly. When the driver tries to modify > the register, it reads it, modifies some bits and writes back. Because the > read bytes were swapped, this often results in an invalid value to be > written. In turn, this causes cp2108 respond with a stall. The stall > sometimes doesn't clear properly and cp2108 starts responding to following > valid commands also with stalls, effectively failing. > > Signed-off-by: Konstantin Shkolnyy <konstantin.shkolnyy@gmail.com> > --- > drivers/usb/serial/cp210x.c | 70 ++++++++++++++++++++++++++++++++++++++++++--- > 1 file changed, 66 insertions(+), 4 deletions(-)
> +/* > + * Must always be called instead of cp210x_get_config(CP210X_GET_LINE_CTL) > + * to workaround cp2108 bug and get correct value. > + */ > +static int cp210x_get_line_ctl(struct usb_serial_port *port, > + unsigned int *ctl)
No need to break this line anymore.
> +{ > + struct cp210x_port_private *port_priv = usb_get_serial_port_data(port); > + int err; > + > + err = cp210x_get_config(port, CP210X_GET_LINE_CTL, ctl, 2); > + if (err) > + return err; > + > + /* Workaround swapped bytes in 16-bit value from CP210X_GET_LINE_CTL */ > + if (port_priv->has_swapped_line_ctl) > + *ctl = swab16((u16)(*ctl)); > + > + return 0; > +}
> @@ -883,6 +940,7 @@ static int cp210x_port_probe(struct usb_serial_port *port) > struct usb_serial *serial = port->serial; > struct usb_host_interface *cur_altsetting; > struct cp210x_port_private *port_priv; > + int err; > > port_priv = kzalloc(sizeof(*port_priv), GFP_KERNEL); > if (!port_priv) > @@ -893,6 +951,10 @@ static int cp210x_port_probe(struct usb_serial_port *port) > > usb_set_serial_port_data(port, port_priv); > > + err = cp210x_detect_swapped_line_ctl(port); > + if (err) > + kfree(port_priv);
You forgot to return err here...
> + > return 0; > }
I gave the series a really quick test on an cp2102-device I had lying around. I assume you verified the changes on some other older devices as well?
Fix the above, and I'll queue this up for 4.4-rc.
Thanks, Johan
| |