linux-kernel - Re: [Xen-devel] [PATCH v2] xen, input: try to read screen resolution for xen-kbdfront

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Date:   Fri, 27 Jan 2017 09:31:19 +0100
From:   Juergen Gross <jgross@...e.com>
To:     Oleksandr Andrushchenko <andr2000@...il.com>,
        linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
        xen-devel@...ts.xenproject.org
Cc:     dmitry.torokhov@...il.com
Subject: Re: [Xen-devel] [PATCH v2] xen, input: try to read screen resolution
 for xen-kbdfront

On 27/01/17 09:26, Oleksandr Andrushchenko wrote:
> On 01/27/2017 10:14 AM, Juergen Gross wrote:
>> On 27/01/17 08:53, Oleksandr Andrushchenko wrote:
>>> On 01/27/2017 09:46 AM, Juergen Gross wrote:
>>>> On 27/01/17 08:21, Oleksandr Andrushchenko wrote:
>>>>> On 01/27/2017 09:12 AM, Juergen Gross wrote:
>>>>>> Instead of using the default resolution of 800*600 for the pointing
>>>>>> device of xen-kbdfront try to read the resolution of the (virtual)
>>>>>> framebuffer device. Use the default as fallback only.
>>>>>>
>>>>>> Signed-off-by: Juergen Gross <jgross@...e.com>
>>>>>> ---
>>>>>> V2: get framebuffer resolution only if CONFIG_FB (Dmitry Torokhov)
>>>>>> ---
>>>>>>     drivers/input/misc/xen-kbdfront.c | 15 ++++++++++++---
>>>>>>     1 file changed, 12 insertions(+), 3 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/input/misc/xen-kbdfront.c
>>>>>> b/drivers/input/misc/xen-kbdfront.c
>>>>>> index 3900875..3aae9b4 100644
>>>>>> --- a/drivers/input/misc/xen-kbdfront.c
>>>>>> +++ b/drivers/input/misc/xen-kbdfront.c
>>>>>> @@ -16,6 +16,7 @@
>>>>>>     #include <linux/kernel.h>
>>>>>>     #include <linux/errno.h>
>>>>>>     #include <linux/module.h>
>>>>>> +#include <linux/fb.h>
>>>>>>     #include <linux/input.h>
>>>>>>     #include <linux/slab.h>
>>>>>>     @@ -108,7 +109,7 @@ static irqreturn_t input_handler(int rq, void
>>>>>> *dev_id)
>>>>>>     static int xenkbd_probe(struct xenbus_device *dev,
>>>>>>                       const struct xenbus_device_id *id)
>>>>>>     {
>>>>>> -    int ret, i;
>>>>>> +    int ret, i, width, height;
>>>>>>         unsigned int abs;
>>>>>>         struct xenkbd_info *info;
>>>>>>         struct input_dev *kbd, *ptr;
>>>>>> @@ -173,9 +174,17 @@ static int xenkbd_probe(struct xenbus_device
>>>>>> *dev,
>>>>>>         ptr->id.product = 0xfffe;
>>>>>>           if (abs) {
>>>>>> +        width = XENFB_WIDTH;
>>>>>> +        height = XENFB_HEIGHT;
>>>>>> +#ifdef CONFIG_FB
>>>>>> +        if (registered_fb[0]) {
>>>>> This still will not help if FB gets registered after kbd+ptr
>>>> Hmm, so you think I should add a call to fb_register_client() to get
>>>> events for new registered framebuffer devices?
>>> yes, but also pay attention to CONFIG_FB_NOTIFY: you may still
>>> end up w/o notification.
>> Okay, that's not worse than today.
> agree
>>>> This would probably work. I'll have a try.
>>>>
>>>>
>>>> Thanks,
>>>>
>>>> Juergen
>>> My bigger concern here is that we try to tie keyboard and pointer device
>>> to the framebuffer. IMO, these are independent parts of the system and
>>> the relation
>>> depends on the use-case. One can have graphics enabled w/o framebuffer
>>> at all, e.g.
>>> DRM/KMS + OpenGLES + Weston + kbd + ptr...
>> Again: that's a use case which will work as today. The current defaults
>> are being used.
>>
>> The question is whether we should add a module parameter switching off
>> the automatic adaption of the resolution as there might be use cases
>> where we don't want this feature.
> I think for those who doesn't want this resolution there is
> still a possibility to change it on backend's XenbusStateConnected
> So, no need for module parameter, IMO

Fine.

I'll send V3 soon.


Juergen