acd45c5679
UDL driver uses a semaphore for controlling the emptiness of FIFO in a slightly funky way. This patch replaces it with a wait queue and controls the emptiness with the standard wait_event*() macro instead, which is a more straightforward implementation. While we are at it, drop the dead code for delayed semaphore down, too. Tested-by: Thomas Zimmermann <tzimmermann@suse.de> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de> Link: https://patchwork.freedesktop.org/patch/msgid/20220804075826.27036-2-tiwai@suse.de