Re: [PATCH 3/5] usb: gadget: gmidi: remove bus powered requirement on bmAttributes

Felipe Balbi
2016-03-04T07:17:31Z

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Hi,

"Felipe F. Tonello" <eu@felipetonello.com> writes:
> [ text/plain ]
> This gadget uses a bmAttributes and MaxPower that requires the USB bus to be
> powered from the host, which is not correct because this configuration is device
> specific, not a USB-MIDI requirement.
>
> This patch adds two modules parameters, bmAttributes and MaxPower, that allows
> the user to set those flags. The default values are what the gadget used to use
> for backward compatibility.
>
> Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
> ---
> drivers/usb/gadget/legacy/gmidi.c | 14 ++++++++++++--
> 1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/gadget/legacy/gmidi.c b/drivers/usb/gadget/legacy/gmidi.c
> index fc2ac150f5ff..0553435cc360 100644
> --- a/drivers/usb/gadget/legacy/gmidi.c
> +++ b/drivers/usb/gadget/legacy/gmidi.c
> @@ -63,6 +63,14 @@ static unsigned int out_ports = 1;
> module_param(out_ports, uint, S_IRUGO);
> MODULE_PARM_DESC(out_ports, "Number of MIDI output ports");
>
> +static unsigned int bmAttributes = USB_CONFIG_ATT_ONE;
> +module_param(bmAttributes, uint, S_IRUGO);
> +MODULE_PARM_DESC(bmAttributes, "Configuration Descriptor's bmAttributes parameter");
> +
> +static unsigned int MaxPower = CONFIG_USB_GADGET_VBUS_DRAW;
> +module_param(MaxPower, uint, S_IRUGO);
> +MODULE_PARM_DESC(MaxPower, "Used to calculate Configuration Descriptor's bMaxPower parameter");

you didn't run checkpatch, did you ? Also, are you sure you will need to
change this by simply reloading the module ? I'm not convinced.

> @@ -119,8 +127,8 @@ static struct usb_configuration midi_config = {
> .label = "MIDI Gadget",
> .bConfigurationValue = 1,
> /* .iConfiguration = DYNAMIC */
> - .bmAttributes = USB_CONFIG_ATT_ONE,

nack, nackety nack nack nack :-)

USB_CONFIG_ATT_ONE *must* always be set. With your module parameter you
give users the oportunity to violate USB spec.

--
balbi

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