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@xxxxxxxxx>
> ---
> 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
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