Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752343AbcJCFkV (ORCPT ); Mon, 3 Oct 2016 01:40:21 -0400 Received: from mail-it0-f65.google.com ([209.85.214.65]:34482 "EHLO mail-it0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752026AbcJCFkO (ORCPT ); Mon, 3 Oct 2016 01:40:14 -0400 MIME-Version: 1.0 In-Reply-To: <1474893160-12321-2-git-send-email-ard.biesheuvel@linaro.org> References: <1474893160-12321-1-git-send-email-ard.biesheuvel@linaro.org> <1474893160-12321-2-git-send-email-ard.biesheuvel@linaro.org> From: Alexandre Courbot Date: Mon, 3 Oct 2016 14:39:53 +0900 Message-ID: Subject: Re: [Nouveau] [PATCH v4 1/3] drm/nouveau: set streaming DMA mask early To: Ard Biesheuvel Cc: Linux Kernel Mailing List , Ben Skeggs , David Airlie , "dri-devel@lists.freedesktop.org" , "nouveau@lists.freedesktop.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1887 Lines: 39 On Mon, Sep 26, 2016 at 9:32 PM, Ard Biesheuvel wrote: > Some subdevices (i.e., fb/nv50.c and fb/gf100.c) map a scratch page using > dma_map_page() way before the TTM layer has had a chance to set the DMA > mask. This may prevent the driver from loading at all on platforms whose > system memory is not covered by the default DMA mask of 32-bit (i.e., when > all RAM is above 4 GB). > > So set a preliminary DMA mask right after constructing the PCI device, and > base it on the .dma_bits member of the MMU subdevice, which is what the TTM > layer will base the DMA mask on as well. > > Signed-off-by: Ard Biesheuvel > --- > drivers/gpu/drm/nouveau/nouveau_drm.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c > index 652ab111dd74..e61e9a0adb51 100644 > --- a/drivers/gpu/drm/nouveau/nouveau_drm.c > +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c > @@ -361,6 +361,17 @@ static int nouveau_drm_probe(struct pci_dev *pdev, > > pci_set_master(pdev); > > + /* > + * Set a preliminary DMA mask based on the .dma_bits member of the > + * MMU subdevice. This allows other subdevices to create DMA mappings > + * in their init() function, which are called before the TTM layer sets > + * the DMA mask definitively. > + * This is necessary for platforms where the default DMA mask of 32 > + * does not cover any system memory, i.e., when all RAM is > 4 GB. > + */ > + dma_set_mask_and_coherent(device->dev, > + DMA_BIT_MASK(device->mmu->dma_bits)); I would just move this to nvkm_device_pci_new() so that it perfectly mirrors the same call done in nvkm_device_tegra_new(), which was done for the same purpose. Otherwise, looks good to me.