linux-kernel - Re: [PATCH v5 5/5] Add ioctls to enable and disable local controls on an instrument

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Date:	Wed, 18 Nov 2015 11:41:30 +0200
From:	Andy Shevchenko <andy.shevchenko@...il.com>
To:	Dave Penkler <dpenkler@...il.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	peter.chen@...escale.com, teuniz@...il.com,
	USB <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 5/5] Add ioctls to enable and disable local controls on
 an instrument

On Wed, Nov 18, 2015 at 10:38 AM, Dave Penkler <dpenkler@...il.com> wrote:
> These ioctls provide support for the USBTMC-USB488 control requests
> for REN_CONTROL, GO_TO_LOCAL and LOCAL_LOCKOUT

Couple of comments below.

> diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
> index 2358991..d416a5f 100644
> --- a/drivers/usb/class/usbtmc.c
> +++ b/drivers/usb/class/usbtmc.c
> @@ -476,6 +476,62 @@ static int usbtmc488_ioctl_read_stb(struct usbtmc_device_data *data,
>         return rv;
>  }
>
> +static int usbtmc488_ioctl_simple(struct usbtmc_device_data *data,
> +                               unsigned long arg,
> +                               unsigned int cmd)
> +{
> +       u8 *buffer;
> +       struct device *dev = &data->intf->dev;
> +       int rv;
> +       unsigned int val;
> +       u16 wValue;
> +
> +       if (!(data->usb488_caps & USBTMC488_CAPABILITY_SIMPLE))
> +               return -EINVAL;
> +
> +       buffer = kmalloc(8, GFP_KERNEL);
> +       if (!buffer)
> +               return -ENOMEM;
> +
> +       if (cmd == USBTMC488_REQUEST_REN_CONTROL) {
> +               rv = copy_from_user(&val, (void __user *)arg, sizeof(val));
> +               if (rv) {
> +                       rv = -EFAULT;
> +                       goto exit;
> +               }
> +               wValue = val ? 1 : 0;
> +       } else {
> +               wValue = 0;
> +       }
> +
> +       rv = usb_control_msg(data->usb_dev,
> +                       usb_rcvctrlpipe(data->usb_dev, 0),
> +                       cmd,
> +                       USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
> +                       wValue,
> +                       data->ifnum,
> +                       buffer, 0x01, USBTMC_TIMEOUT);
> +

Redundant empty line

> +       if (rv < 0) {
> +               dev_err(dev, "simple usb_control_msg failed %d\n", rv);
> +               goto exit;
> +       } else if (rv != 1) {
> +               dev_warn(dev, "simple usb_control_msg returned %d\n", rv);

Actually here what king of results could be? 0? 2+? In all cases of
error you have to provide an error code.

> +               goto exit;
> +       }
> +
> +       if (buffer[0] != USBTMC_STATUS_SUCCESS) {
> +               dev_err(dev, "simple control status returned %x\n", buffer[0]);
> +               rv = -EIO;
> +               goto exit;
> +       }
> +       rv = 0;
> +
> + exit:
> +       kfree(buffer);
> +       return rv;
> +}
> +

-- 
With Best Regards,
Andy Shevchenko
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