• Daniel Vetter's avatar
    drm: remove FASYNC support · b0e898ac
    Daniel Vetter authored
    So I've stumbled over drm_fasync and wondered what it does. Digging
    that up is quite a story.
    
    First I've had to read up on what this does and ended up being rather
    bewildered why peopled loved signals so much back in the days that
    they've created SIGIO just for that ...
    
    Then I wondered how this ever works, and what that strange "No-op."
    comment right above it should mean. After all calling the core fasync
    helper is pretty obviously not a noop. After reading through the
    kernels FASYNC implementation I've noticed that signals are only sent
    out to the processes attached with FASYNC by calling kill_fasync.
    
    No merged drm driver has ever done that.
    
    After more digging I've found out that the only driver that ever used
    this is the so called GAMMA driver. I've frankly never heard of such a
    gpu brand ever before. Now FASYNC seems to not have been the only bad
    thing with that driver, since Dave Airlie removed it from the drm
    driver with prejudice:
    
    commit 1430163b4bbf7b00367ea1066c1c5fe85dbeefed
    Author: Dave Airlie <airlied@linux.ie>
    Date:   Sun Aug 29 12:04:35 2004 +0000
    
        Drop GAMMA DRM from a great height ...
    
    Long story short, the drm fasync support seems to be doing absolutely
    nothing. And the only user of it was never merged into the upstream
    kernel. And we don't need any fops->fasync callback since the fcntl
    implementation in the kernel already implements the noop case
    correctly.
    
    So stop this particular cargo-cult and rip it all out.
    
    v2: Kill drm_fasync assignments in rcar (newly added) and imx drivers
    (somehow I've missed that one in staging). Also drop the reference in
    the drm DocBook. ARM compile-fail reported by Rob Clark.
    
    v3: Move the removal of dev->buf_asnyc assignment in drm_setup to this
    patch here.
    
    v4: Actually git add ... tsk.
    
    Cc: Dave Airlie <airlied@linux.ie>
    Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
    Cc: Rob Clark <robdclark@gmail.com>
    Acked-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
    Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
    Reviewed-by: default avatarDavid Herrmann <dh.herrmann@gmail.com>
    Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
    b0e898ac
shmob_drm_drv.c 9.13 KB