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

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Message-ID: <3ec171a9-c38a-87e6-d1f6-5493211dc87e@gmail.com>
Date:   Fri, 27 Jan 2017 10:26:09 +0200
From:   Oleksandr Andrushchenko <andr2000@...il.com>
To:     Juergen Gross <jgross@...e.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 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
>
> Juergen