udlfb: fix sleeping inside spinlock
If a framebuffer device is used as a console, the rendering calls (copyarea, fillrect, imageblit) may be done with the console spinlock held. On udlfb, these function call dlfb_handle_damage that takes a blocking semaphore before acquiring an URB. In order to fix the bug, this patch changes the calls copyarea, fillrect and imageblit to offload USB work to a workqueue. A side effect of this patch is 3x improvement in console scrolling speed because the device doesn't have to be updated after each copyarea call. Signed-off-by:Mikulas Patocka <mpatocka@redhat.com> Cc: Bernie Thompson <bernie@plugable.com> Cc: Ladislav Michl <ladis@linux-mips.org> Cc: <stable@vger.kernel.org> Signed-off-by:
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
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