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SubjectRe: [PATCH v3 2/2] Input: xen-kbdfront - allow better run-time configuration
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On 05/17/2018 12:08 AM, Dmitry Torokhov wrote:
> On Wed, May 16, 2018 at 08:47:30PM +0300, Oleksandr Andrushchenko wrote:
>> On 05/16/2018 08:15 PM, Dmitry Torokhov wrote:
>>> Hi Oleksandr,
>>>
>>> On Mon, May 14, 2018 at 05:40:29PM +0300, Oleksandr Andrushchenko wrote:
>>>> @@ -211,93 +220,114 @@ static int xenkbd_probe(struct xenbus_device *dev,
>>>> if (!info->page)
>>>> goto error_nomem;
>>>> - /* Set input abs params to match backend screen res */
>>>> - abs = xenbus_read_unsigned(dev->otherend,
>>>> - XENKBD_FIELD_FEAT_ABS_POINTER, 0);
>>>> - ptr_size[KPARAM_X] = xenbus_read_unsigned(dev->otherend,
>>>> - XENKBD_FIELD_WIDTH,
>>>> - ptr_size[KPARAM_X]);
>>>> - ptr_size[KPARAM_Y] = xenbus_read_unsigned(dev->otherend,
>>>> - XENKBD_FIELD_HEIGHT,
>>>> - ptr_size[KPARAM_Y]);
>>>> - if (abs) {
>>>> - ret = xenbus_write(XBT_NIL, dev->nodename,
>>>> - XENKBD_FIELD_REQ_ABS_POINTER, "1");
>>>> - if (ret) {
>>>> - pr_warn("xenkbd: can't request abs-pointer\n");
>>>> - abs = 0;
>>>> - }
>>>> - }
>>>> + /*
>>>> + * The below are reverse logic, e.g. if the feature is set, then
>>>> + * do not expose the corresponding virtual device.
>>>> + */
>>>> + with_kbd = !xenbus_read_unsigned(dev->nodename,
>>>> + XENKBD_FIELD_FEAT_DSBL_KEYBRD, 0);
>>>> - touch = xenbus_read_unsigned(dev->nodename,
>>>> - XENKBD_FIELD_FEAT_MTOUCH, 0);
>>>> - if (touch) {
>>>> + with_ptr = !xenbus_read_unsigned(dev->nodename,
>>>> + XENKBD_FIELD_FEAT_DSBL_POINTER, 0);
>>>> +
>>>> + /* Direct logic: if set, then create multi-touch device. */
>>>> + with_mtouch = xenbus_read_unsigned(dev->nodename,
>>>> + XENKBD_FIELD_FEAT_MTOUCH, 0);
>>>> + if (with_mtouch) {
>>>> ret = xenbus_write(XBT_NIL, dev->nodename,
>>>> XENKBD_FIELD_REQ_MTOUCH, "1");
>>>> if (ret) {
>>>> pr_warn("xenkbd: can't request multi-touch");
>>>> - touch = 0;
>>>> + with_mtouch = 0;
>>>> }
>>>> }
>>> Does it make sense to still end up calling xenkbd_connect_backend() when
>>> all interfaces (keyboard, pointer, and multitouch) are disabled? Should
>>> we do:
>>>
>>> if (!(with_kbd || || with_ptr || with_mtouch))
>>> return -ENXIO;
>>>
>>> ?
>> It does make sense. Then we probably need to move all xenbus_read_unsigned
>> calls to the very beginning of the .probe, so no memory allocations are made
>> which will be useless if we return -ENXIO, e.g. something like
>>
>> static int xenkbd_probe(struct xenbus_device *dev,
>>                   const struct xenbus_device_id *id)
>> {
>>     int ret, i;
>>     bool with_mtouch, with_kbd, with_ptr;
>>     struct xenkbd_info *info;
>>     struct input_dev *kbd, *ptr, *mtouch;
>>
>> <read with_mtouch, with_kbd, with_ptr here>
>>
>> if (!(with_kbd | with_ptr | with_mtouch))
>>         return -ENXIO;
>>
>> Does the above looks ok?
> Yes. Another option is to keep the check where I suggested and do
>
> if (...) {
> ret = -ENXIO;
> goto error;
> }
>
> Whichever you prefer is fine with me.
I will go with the change you suggested and
I'll send v4 tomorrow then.
> Thanks.
>
Thank you,
Oleksandr

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