Hi Takashi, > -----Original Message----- > From: Takashi Iwai [mailto:ti...@suse.de] > Sent: Wednesday, March 02, 2016 4:57 PM > To: Yang, Libin > Cc: libin.y...@linux.intel.com; intel-gfx@lists.freedesktop.org; > conselv...@gmail.com; jani.nik...@linux.intel.com; > ville.syrj...@linux.intel.com; Vetter, Daniel > Subject: Re: [PATCH] drm/i915: add audio_ptr pointer check > > On Wed, 02 Mar 2016 08:59:23 +0100, > Yang, Libin wrote: > > > > Hi Takashi, > > > > > -----Original Message----- > > > From: Takashi Iwai [mailto:ti...@suse.de] > > > Sent: Wednesday, March 02, 2016 3:44 PM > > > To: libin.y...@linux.intel.com > > > Cc: intel-gfx@lists.freedesktop.org; conselv...@gmail.com; > > > jani.nik...@linux.intel.com; ville.syrj...@linux.intel.com; Vetter, > Daniel; > > > ti...@suse.de; Yang, Libin > > > Subject: Re: [PATCH] drm/i915: add audio_ptr pointer check > > > > > > On Wed, 02 Mar 2016 03:24:31 +0100, > > > libin.y...@linux.intel.com wrote: > > > > > > > > From: Libin Yang <libin.y...@linux.intel.com> > > > > > > > > check to make sure audio_ptr is not NULL before > > > > using it. > > > > > > I don't think non-NULL is mandatory. If any invalid access is seen, > > > it should be fixed rather in the audio side. > > > > When I enable MST with other patches (not submitted so far), > > I found system may be random hang when boot up. > > > > After apply this patch and another patch (I sent the patch in > > ALSA Mail list: ALSA: hda - hdmi defer to register acomp eld notifier), > > the hang issue is fixed. > > > > I make the patch because in sound driver side, setting audio_ptr and > > audio_ops is not in the lock. I'm wondering that the compiler or CPU > > may optimize and change the setting order (the gfx code and alsa code > > may run parallelly?). > > There are several ways to deal with such a thing. An easy one would > be the memory barrier.
Yes, agree to use mb. It will be easier and safer. I think wmb() should be enough for this case, right? I will do the stress test on mb. Regards, Libin > > > Takashi _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
