On Tue, 23 Mar 2021 12:23:16 +0100, Andrey Grodzovsky wrote: > > Just an update, i found the issue which was actually to wake up the HW > before doing stop/restart (using pm_runtime_get_sync), also handled > protecting from concurrent snd_pcm_ioctls accessing the registers > while the BAR is unmapped. Can go through BAR move while aplay is > running now. > > Once again, would be happy for any comments on the code - > https://cgit.freedesktop.org/~agrodzov/linux/log/?h=yadro/pcie_hotplug/movable_bars_v9.1 Hrm, this kind of change is a bit scary; we have some mechanism to stop the HD-audio hardware operation (e.g. for loading the DSP for CA0132 codec), but it's pretty hackish and error-prone. Do we really need the BAR remap while operating the sound streaming? That is, can't we simply refuse the remap if it's in operation? If it can be refused, we may avoid a big locking or such. thanks, Takashi > > > Andrey > > On 2021-03-19 5:22 p.m., Andrey Grodzovsky wrote: > > Hi, I am working on adding AMD related drivers support for PCIe BARs > > move feature developed by Sergei > > (https://linuxplumbersconf.org/event/7/contributions/847/attachments/584/1035/lpc2020_sergmir.pdf). > > > > His feature is still not upstream, all his code and mine on top can > > be seen here - > > https://cgit.freedesktop.org/~agrodzov/linux/log/?h=yadro/pcie_hotplug/movable_bars_v9.1 > > > > I did basic implementation fro amdgpu driver and now I am doing the > > same for snd_hda_intel to support our on GPU Azalia audio > > chips. This relevant commit is here - > > https://cgit.freedesktop.org/~agrodzov/linux/commit/?h=yadro/pcie_hotplug/movable_bars_v9.1&id=7ec0f60633e898cb941cebb3cd18aae1374fc365 > > > > Any driver that wants to support movable BARs needs to implement > > rescan_prepare, rescan_done and bar_fixed callbacks where > > rescan_prepare needs to stop HW/SW and unamp all MMIO mappings and > > rescan_done needs to ioremap the BAR from it's new MMIO location and > > restart HW/SW. > > > > I am able currently to trigger BARs move by sysfs using > > "/sys/bus/pci/rescan" and the driver will go through the sequence I > > described above without hangs. Problem is that after this when i try > > to use mplayer I am getting following errors: > > > > andrey@andrey-test:~$ sudo mplayer -ao alsa:device=hw=0.3 > > Downloads/file_example_MP3_5MG.mp3 > > MPlayer 1.3.0 (Debian), built with gcc-9 (C) 2000-2016 MPlayer Team > > do_connect: could not connect to socket > > connect: No such file or directory > > Failed to open LIRC support. You will not be able to use your remote > > control. > > > > Playing Downloads/file_example_MP3_5MG.mp3. > > libavformat version 58.29.100 (external) > > Audio only file format detected. > > Load subtitles in Downloads/ > > ========================================================================== > > Opening audio decoder: [mpg123] MPEG 1.0/2.0/2.5 layers I, II, III > > AUDIO: 44100 Hz, 2 ch, s16le, 320.0 kbit/22.68% (ratio: 40000->176400) > > Selected audio codec: [mpg123] afm: mpg123 (MPEG 1.0/2.0/2.5 layers > > I, II, III) > > ========================================================================== > > AO: [alsa] 44100Hz 2ch s16le (2 bytes per sample) > > Video: no video > > Starting playback... > > A: 0.1 (00.0) of 132.0 (02:12.0) ??,?% > > Audio device got stuck! > > > > and in dmesg I see > > [ 365.355518] snd_hda_codec_hdmi hdaudioC0D0: Unable to sync > > register 0x2f0d00. -5 > > > > Also I see 296.619014] snd_hda_intel 0000:0a:00.1: CORB reset > > timeout#2, CORBRP = 65535 error during the rescan_done callback > > execution > > > > I know it has to do with the move of BAR's MMIO address because when i > > disallow BAR migration by returning true from bar_fixed callback I > > have no such errors and mplayer works fine. > > > > I enabled MMIO trace and didn't see that post BAR move there is a > > wrong MMIO access - all of them are from the new MMIO base offset - > > 0xfcd80000 (trace attached including mmio trace and dmesg) > > > > I would be happy for any idea on this and any comment on the > > correctness of my sequence in the code > > > > Andrey >
