On 20-10-30 18:34:19, Michael R Sweet wrote:
> The usb_f_printer gadget driver uses a default q_len value of *0* which prevents
> any IO from occurring. Moreover, once the driver is instantiated it is
> impossible to change the q_len value.
>
> The following patch uses a default q_len value of 10 which matches the legacy
> g_printer gadget driver. This minimizes the possibility that you end up with a
> non-working printer gadget. It is still possible to set the q_len to a
> different value using the configfs path of the same name.
>
> Signed-off-by: Michael R Sweet <msweet@xxxxxxxxxx>
Reviewed-by: Peter Chen <peter.chen@xxxxxxx>
Peter
> ---
> drivers/usb/gadget/function/f_printer.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/usb/gadget/function/f_printer.c b/drivers/usb/gadget/function/f_printer.c
> index 9c7ed2539ff7..4f3161005e4f 100644
> --- a/drivers/usb/gadget/function/f_printer.c
> +++ b/drivers/usb/gadget/function/f_printer.c
> @@ -50,6 +50,8 @@
> #define GET_PORT_STATUS 1
> #define SOFT_RESET 2
>
> +#define DEFAULT_Q_LEN 10 /* same as legacy g_printer gadget */
> +
> static int major, minors;
> static struct class *usb_gadget_class;
> static DEFINE_IDA(printer_ida);
> @@ -1317,6 +1319,9 @@ static struct usb_function_instance *gprinter_alloc_inst(void)
> opts->func_inst.free_func_inst = gprinter_free_inst;
> ret = &opts->func_inst;
>
> + /* Make sure q_len is initialized, otherwise the bound device can't support read/write! */
> + opts->q_len = DEFAULT_Q_LEN;
> +
> mutex_lock(&printer_ida_lock);
>
> if (ida_is_empty(&printer_ida)) {
> --
> 2.17.1
>
--
Thanks,
Peter Chen
