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 <[email protected]>
Reviewed-by: Peter Chen <[email protected]> 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
