Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S941866AbcJFM5T (ORCPT ); Thu, 6 Oct 2016 08:57:19 -0400 Received: from mail-it0-f43.google.com ([209.85.214.43]:36924 "EHLO mail-it0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934042AbcJFM5M (ORCPT ); Thu, 6 Oct 2016 08:57:12 -0400 MIME-Version: 1.0 In-Reply-To: References: <1474893160-12321-1-git-send-email-ard.biesheuvel@linaro.org> <1474893160-12321-2-git-send-email-ard.biesheuvel@linaro.org> From: Ard Biesheuvel Date: Thu, 6 Oct 2016 13:57:10 +0100 Message-ID: Subject: Re: [Nouveau] [PATCH v4 1/3] drm/nouveau: set streaming DMA mask early To: Alexandre Courbot 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: 2022 Lines: 42 On 3 October 2016 at 06:39, Alexandre Courbot wrote: > 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. OK, will do that.