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Subject: Re: [Xen-devel] [PATCH v2] xen, input: try to read screen resolution
 for xen-kbdfront
To: Juergen Gross <jgross@suse.com>, linux-kernel@vger.kernel.org,
        linux-input@vger.kernel.org, xen-devel@lists.xenproject.org
References: <20170127071239.913-1-jgross@suse.com>
 <5cbb25fa-2dee-f82f-e656-bc733c67c398@gmail.com>
 <a27287e1-463e-c91b-5a0f-512baf08ef95@suse.com>
Cc: dmitry.torokhov@gmail.com
From: Oleksandr Andrushchenko <andr2000@gmail.com>
Message-ID: <803639e7-e62e-cce1-6108-05a727612937@gmail.com>
Date: Fri, 27 Jan 2017 09:53:50 +0200
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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@suse.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.
>
> 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...