Hi Takashi We verified on Ubuntu 19.10 with kernel 5.4.0.0-050400-generic (please refer to attachment), the result is positive which symptom doesn't happen anymore once I played music or video sound output through Dell S2718D Type-C monitor. It seems had some fix in latest kernel. Thanks. -----Original Message----- From: Takashi Iwai Sent: Friday, January 3, 2020 5:16 PM To: Cheng. AJ (TPE) Cc: intel-gfx@lists.freedesktop.org; alsa-devel@alsa-project.org; nathan.d.ciobanu@linux.intel.com; Wang. CindyXT (TPE) ; Ye. Nelson (TPE) ; Yap. Shane (TPE) ; Kao. Lucien (TPE) ; Tseng. Evan (TPE) Subject: Re: [alsa-devel] USB Type-C monitor flashes once when play a video file after unplug and re-plug the monitor On Fri, 03 Jan 2020 02:57:03 +0100, wrote: > > Hi Sirs, > Here is chromebook SW team from Compal. > As the mail title, we hit issue that the external monitor will flash once when play video after hot pluging. > We can reproduce not only on chromebook but also ubuntu 16.04. > There has higher failure rate with Dell Solomon dock and Dell S2718D monitor. > > We found adding the delay in "sound/pci/hda/patch_hdmi.c " can fix > this issue.(as the attachment) May need your help to review and advice. Thanks. > > Here is the issue number in gitlab for more detail. > https://gitlab.freedesktop.org/drm/intel/issues/318 Could you check whether it still happens with the latest upstream kernel, at least 5.4.y, if it wasn't tested yet? I don't want to put a long delay just because of random reason unless it's really mandatory. I'm wondering whether the recent write-sync change improves the situation, so let's check the recent code. thanks, Takashi > > > > AJ Cheng > NID/NID1 > e-mail: AJ_Cheng@compal.com > Tel: +886-2-8797-8599 ext. 17561 > Mobile : +886-932827829 > COMPAL Electronics, Inc. > > [2 flash_once.diff ] > > _______________________________________________ > Alsa-devel mailing list > Alsa-devel@alsa-project.org > https://mailman.alsa-project.org/mailman/listinfo/alsa-devel