"The patch is probably fine. But I can't invent an explanation if I don't know what the problem is." @Jani @libin, is it possible for you to help contact Intel graphics hardware design engineer to get the reason why M/N doesn't work as you implemented in kernel code in Kabylake platform? I don't find good reason in bspec. Thanks. -----Original Message----- From: Jani Nikula [mailto:jani.nikula@xxxxxxxxxxxxxxx] Sent: Friday, May 26, 2017 7:01 PM To: Wang, Quanxian <quanxian.wang@xxxxxxxxx>; intel-gfx@xxxxxxxxxxxxxxxxxxxxx Cc: Yang, Libin <libin.yang@xxxxxxxxx> Subject: RE: [PATCH] Defined NM doesn't work on KBL and uses automatic N/M. On Fri, 26 May 2017, "Wang, Quanxian" <quanxian.wang@xxxxxxxxx> wrote: > [Wang, Quanxian] in Ubuntu 17.04, we do audio testing on KBL/SKL/APL > and more, the audio doesn't work on KBL specially, and other platform > works fine. Even if with latest upstream kernel, but it works on 4.8 > kernel. Therefore It is a regression issue. After investigation, we > found it is caused by commit > "6014ac122ed081feca99217bc57b2e15c7fc1a51] drm/i915/audio: set proper > N/M in modeset". Therefore I provided this patch. If it's a regression, we need to backport the fix to stable kernels, and the patch needs annotation: Fixes: 6014ac122ed0 ("drm/i915/audio: set proper N/M in modeset") Cc: <stable@xxxxxxxxxxxxxxx> # v4.10+ > After getting suggestion from you and Libin, we do more testing on 4K > monitor for audio delay issue. Also talked with Libin why not use > transcoder disable/enable process described in bspec, it will affect > performance. > > This is the whole story. You can check LCK number 3791 in Intel JIRA > about that. Actually, I can't. And the commit message needs to have the explanation. I still do not know what the bug is specifically, or why Kabylake, and only Kabylake, needs this. > [Wang, Quanxian] Basically if upstream could provide a reasonable > patch, it will appreciate since you are expert in this area. > Thanks for your understanding. The patch is probably fine. But I can't invent an explanation if I don't know what the problem is. BR, Jani. -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
