Re: [linux-usb-devel] [PATCH] Driver for Apple Cinema Display

[Oliver Neukum]

Am Freitag, 26. Mai 2006 11:15 schrieb Michael Hanselmann:
> +static int appledisplay_bl_update_status(struct backlight_device *bd)
> +{
> +       struct appledisplay *pdata = class_get_devdata(&bd->class_dev);
> +       char buffer[2];
> +       int retval;
> +
> +       buffer[0] = 0x10;
> +       buffer[1] = bd->props->brightness;
> +
> +       retval = usb_control_msg(
> +               pdata->udev,
> +               usb_sndctrlpipe(pdata->udev, 0),
> +               USB_REQ_SET_REPORT,
> +               USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
> +               ACD_USB_BRIGHTNESS,
> +               0,
> +               buffer,
> +               sizeof(buffer),
> +               250);
> +
> +       return retval;
> +}

DMA on the stack. You must not do this. Allocate the buffer with kmalloc.

        Regards
                Oliver
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