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Re: [PATCH] ALSA: hda - allow 40 bit DMA mask for NVidia devices

From Ard Biesheuvel <ard.biesheuvel@linaro.org>
Newsgroups linux.kernel
Subject Re: [PATCH] ALSA: hda - allow 40 bit DMA mask for NVidia devices
Date 2016-10-18 14:50 +0200
Message-ID <stC0f-1Ip-3@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>
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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.

> 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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Thread

[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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