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Groups > linux.kernel > #1502979
| From | Mike Travis <travis@sgi.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] ALSA: hda - allow 40 bit DMA mask for NVidia devices |
| Date | 2016-10-18 15:10 +0200 |
| Message-ID | <stCjw-25f-19@gated-at.bofh.it> (permalink) |
| References | <stiXw-5Qr-23@gated-at.bofh.it> <stzOF-lH-1@gated-at.bofh.it> <stC0f-1Ip-5@gated-at.bofh.it> <stC0f-1Ip-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 10/18/2016 5:49 AM, Ard Biesheuvel wrote: > On 18 October 2016 at 13:46, Mike Travis <travis@sgi.com> wrote: >> >> Have you tested this change on a system which has physical >> addressing > 40 bits to insure that addresses > 40 bits are >> not simply truncated to an incorrect (mod 40) address? > > The device should never see addresses > 40 bits, given that the DMA > mask is set to 40 bits not 64. I agree that the device should never see that. But how is that restriction imposed? If a user presents an buffer address > 40 bits how would that be converted to useful buffer at <= 40 bits? I believe I tried this (at the time the kernel was at version 2.6) and it did not work. Since audio I/O was such a low (relative) bandwidth, it was not worth the effort to rework the audio code to allow buffers > 32 bits but <= 40 bits. It may have changed since then? > >> By not restricting the addresses to 32 bits you are not >> restricting the device to the DMA32 zone. >> >> This is what caused the original panic on UV systems. >> >> Btw, the newest nVidia GPUs have > 40 bits of DMA address bits. >> > > Thanks, > Ard. >
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[PATCH] ALSA: hda - allow 40 bit DMA mask for NVidia devices Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-10-17 18:30 +0200
Re: [PATCH] ALSA: hda - allow 40 bit DMA mask for NVidia devices Takashi Iwai <tiwai@suse.de> - 2016-10-18 12:30 +0200
Re: [PATCH] ALSA: hda - allow 40 bit DMA mask for NVidia devices Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-10-18 12:30 +0200
Re: [PATCH] ALSA: hda - allow 40 bit DMA mask for NVidia devices Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-10-18 14:50 +0200
Re: [PATCH] ALSA: hda - allow 40 bit DMA mask for NVidia devices Mike Travis <travis@sgi.com> - 2016-10-18 15:10 +0200
Re: [PATCH] ALSA: hda - allow 40 bit DMA mask for NVidia devices Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-10-18 15:20 +0200
Re: [PATCH] ALSA: hda - allow 40 bit DMA mask for NVidia devices Mike Travis <travis@sgi.com> - 2016-10-18 14:50 +0200
Re: [PATCH] ALSA: hda - allow 40 bit DMA mask for NVidia devices Takashi Iwai <tiwai@suse.de> - 2016-10-18 16:20 +0200
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