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Re: [PATCH] drm/fb-helper: Only reject FB changes if FB_MISC_USER_EVENT is set

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On 16/03/17 07:09 PM, Daniel Stone wrote:
> On 16 March 2017 at 09:55, Michel Dänzer <michel@daenzer.net> wrote:
>> Otherwise this can also prevent modesets e.g. for switching VTs.
>>
>> FB_MISC_USER_EVENT is set when the request originates from userspace,
>> which is what we're interested in here according to the DRM_DEBUG
>> output.
>>
>> Bugzilla: https://bugs.freedesktop.org/99841
>> Fixes: 865afb11949e ("drm/fb-helper: reject any changes to the fbdev")
>> Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
>> ---
>>
>> I'm not entirely sure why the values can not match for a VT switch. If
>> anybody thinks this just papers over the real issue, please speak up.
> 
> It happens for me in multi-head with different resolutions. A real
> compositor will set native resolutions with separate framebuffers, and
> then fbcon will try to set one buffer for both outputs. This works on
> the output with the larger resolution, but the one with the smaller
> resolution will fail due to [xy]res_virtual (IIRC) being different.

That's more or less the line of thinking that lead me to writing this
patch, based on the assumption that the fb->* values correspond to what
was set by whatever we're VT switching from. However, it occurred to me
that it's an invalid assumption; fb here is always fb_helper's
framebuffer for fbdev. I think Ville is right that the tests are bogus
in the first place.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer

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[PATCH] drm/fb-helper: Only reject FB changes if FB_MISC_USER_EVENT is set Michel Dänzer <michel@daenzer.net> - 2017-03-16 11:00 +0100
  Re: [PATCH] drm/fb-helper: Only reject FB changes if  FB_MISC_USER_EVENT is set Daniel Stone <daniel@fooishbar.org> - 2017-03-16 11:10 +0100
    Re: [PATCH] drm/fb-helper: Only reject FB changes if  FB_MISC_USER_EVENT is set Michel Dänzer <michel@daenzer.net> - 2017-03-17 10:00 +0100
  Re: [PATCH] drm/fb-helper: Only reject FB changes if  FB_MISC_USER_EVENT is set Ville Syrjälä <ville.syrjala@linux.intel.com> - 2017-03-16 11:10 +0100
    Re: [PATCH] drm/fb-helper: Only reject FB changes if  FB_MISC_USER_EVENT is set Michel Dänzer <michel@daenzer.net> - 2017-03-17 10:10 +0100
      Re: [PATCH] drm/fb-helper: Only reject FB changes if  FB_MISC_USER_EVENT is set Ville Syrjälä <ville.syrjala@linux.intel.com> - 2017-03-17 11:50 +0100
        Re: [PATCH] drm/fb-helper: Only reject FB changes if  FB_MISC_USER_EVENT is set Michel Dänzer <michel@daenzer.net> - 2017-03-17 11:50 +0100
          Re: [PATCH] drm/fb-helper: Only reject FB changes if  FB_MISC_USER_EVENT is set Ville Syrjälä <ville.syrjala@linux.intel.com> - 2017-03-17 12:20 +0100
            Re: [PATCH] drm/fb-helper: Only reject FB changes if  FB_MISC_USER_EVENT is set Michel Dänzer <michel@daenzer.net> - 2017-03-21 04:30 +0100
  [PATCH] drm/fb-helper: Allow var->x/yres(_virtual) < fb->width/height again Michel Dänzer <michel@daenzer.net> - 2017-03-23 10:00 +0100
    Re: [PATCH] drm/fb-helper: Allow var->x/yres(_virtual) <  fb->width/height again Daniel Stone <daniel@fooishbar.org> - 2017-03-23 13:10 +0100
      Re: [PATCH] drm/fb-helper: Allow var->x/yres(_virtual) <  fb->width/height again Daniel Vetter <daniel@ffwll.ch> - 2017-03-23 15:00 +0100
    Re: [PATCH] drm/fb-helper: Allow var->x/yres(_virtual) <  fb->width/height again Stefan Agner <stefan@agner.ch> - 2017-03-24 02:00 +0100

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