On Sat, Jul 14, 2018 at 02:15:24PM +0800, jimqu wrote: > ??? 2018/7/13 17:27, Lukas Wunner ??????: > >On Fri, Jul 13, 2018 at 04:06:02PM +0800, Jim Qu wrote: > >>On modern laptop, there are more and more platforms > >>have two GPUs, and each of them maybe have audio codec > >>for HDMP/DP output. For some dGPU which is no output, > >>audio codec usually is disabled. > >> > >>In currect HDA audio driver, it will set all codec as > >>VGA_SWITCHEROO_DIS, the audio which is binded to UMA > >>will be suspended if user use debugfs to contorl power > >> > >>In HDA driver side, it is difficult to know which GPU > >>the audio has binded to. So set the bound gpu pci dev > >>to vgaswitchroo, the correct audio id will be set in > >>vgaswitchreoo enable function. > >> > >>Signed-off-by: Jim Qu <Jim.Qu at amd.com> > >The approach you've taken in this patch won't work if the HDA controller > >is bound to a driver after both GPUs have already been bound to a driver > >and the handler has already been registered. > > > >That's because vga_switcheroo_enable() is run when two GPUs have registered > >as clients and the handler has also registered. If the HDA controller is > >probed afterwards, its ID will be stuck at VGA_SWITCHEROO_UNKNOWN_ID. > > In genernic speaking, there are two cases , a. audio client is the third > client. b. audio client is not the third client. > > if audio is third client. vga_switcheroo_ready() is true, > vga_switcheroo_enable() can be called in audio client register fuction. > if audio is not the third client, vga_switcheroo_enable() will be called in > the second GFX client register. > In vga_switcheroo_enable() , the first list loop will set two GPU clients' > id, and the second list loop will select audio client, set id by its bound > gpu pci dev. No, if audio is the third client, vga_switcheroo_ready() is *not* true because vgasr_priv.active is true. This is set to true once the two GPUs and the handler have registered. If the audio device registers afterwards, vga_switcheroo_enable() will already have been called. It's never called twice because it sets vgasr_priv.active = true. As a result, the audio device is stuck at VGA_SWITCHEROO_UNKNOWN_ID. Thanks, Lukas
