From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2A5CCC2BC61 for ; Tue, 30 Oct 2018 13:09:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3F68220831 for ; Tue, 30 Oct 2018 13:09:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3F68220831 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727845AbeJ3WDQ (ORCPT ); Tue, 30 Oct 2018 18:03:16 -0400 Received: from gate.crashing.org ([63.228.1.57]:37568 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727705AbeJ3WDQ (ORCPT ); Tue, 30 Oct 2018 18:03:16 -0400 Received: from localhost (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id w9UD9TCI030426; Tue, 30 Oct 2018 08:09:31 -0500 Message-ID: <30359cc433e97739d93e13717b2897e462895097.camel@kernel.crashing.org> Subject: Re: [PATCH] powerpc/npu-dma: Remove NPU DMA ops From: Benjamin Herrenschmidt To: Christoph Hellwig , Alistair Popple Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, mpe@ellerman.id.au Date: Wed, 31 Oct 2018 00:09:29 +1100 In-Reply-To: <20181030125841.GB30158@lst.de> References: <20181030110203.27257-1-alistair@popple.id.au> <20181030125841.GB30158@lst.de> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-1.fc28) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2018-10-30 at 13:58 +0100, Christoph Hellwig wrote: > Please take my patch instead. We have a kernel polcity to not keep > dead code around, and everyone including Linus and the attending IBMers > confirmed this. Let's call a cat a cat ... ;-) It's not *dead* code. It's code that is used by an out of tree driver (which also happen not to be open source). Just making things clear for everybody. Cheers, Ben. > On Tue, Oct 30, 2018 at 10:02:03PM +1100, Alistair Popple wrote: > > The NPU IOMMU is setup to mirror the parent PCIe device IOMMU > > setup. Therefore it does not make sense to call dma operations such as > > dma_map_page, etc. directly on these devices. The existing dma-ops > > simply print a warning if they are ever called, however this is > > unnecessary and the warnings are likely to go unnoticed. > > > > It is instead simpler to remove these operations and let the generic > > DMA code print warnings (eg. via a NULL pointer deref) in cases of > > buggy drivers attempting dma operations on NVLink devices. > > > > Signed-off-by: Alistair Popple > > --- > > arch/powerpc/platforms/powernv/npu-dma.c | 64 ++------------------------------ > > 1 file changed, 4 insertions(+), 60 deletions(-) > > > > diff --git a/arch/powerpc/platforms/powernv/npu-dma.c b/arch/powerpc/platforms/powernv/npu-dma.c > > index 6f60e0931922..75b935252981 100644 > > --- a/arch/powerpc/platforms/powernv/npu-dma.c > > +++ b/arch/powerpc/platforms/powernv/npu-dma.c > > @@ -102,63 +102,6 @@ struct pci_dev *pnv_pci_get_npu_dev(struct pci_dev *gpdev, int index) > > } > > EXPORT_SYMBOL(pnv_pci_get_npu_dev); > > > > -#define NPU_DMA_OP_UNSUPPORTED() \ > > - dev_err_once(dev, "%s operation unsupported for NVLink devices\n", \ > > - __func__) > > - > > -static void *dma_npu_alloc(struct device *dev, size_t size, > > - dma_addr_t *dma_handle, gfp_t flag, > > - unsigned long attrs) > > -{ > > - NPU_DMA_OP_UNSUPPORTED(); > > - return NULL; > > -} > > - > > -static void dma_npu_free(struct device *dev, size_t size, > > - void *vaddr, dma_addr_t dma_handle, > > - unsigned long attrs) > > -{ > > - NPU_DMA_OP_UNSUPPORTED(); > > -} > > - > > -static dma_addr_t dma_npu_map_page(struct device *dev, struct page *page, > > - unsigned long offset, size_t size, > > - enum dma_data_direction direction, > > - unsigned long attrs) > > -{ > > - NPU_DMA_OP_UNSUPPORTED(); > > - return 0; > > -} > > - > > -static int dma_npu_map_sg(struct device *dev, struct scatterlist *sglist, > > - int nelems, enum dma_data_direction direction, > > - unsigned long attrs) > > -{ > > - NPU_DMA_OP_UNSUPPORTED(); > > - return 0; > > -} > > - > > -static int dma_npu_dma_supported(struct device *dev, u64 mask) > > -{ > > - NPU_DMA_OP_UNSUPPORTED(); > > - return 0; > > -} > > - > > -static u64 dma_npu_get_required_mask(struct device *dev) > > -{ > > - NPU_DMA_OP_UNSUPPORTED(); > > - return 0; > > -} > > - > > -static const struct dma_map_ops dma_npu_ops = { > > - .map_page = dma_npu_map_page, > > - .map_sg = dma_npu_map_sg, > > - .alloc = dma_npu_alloc, > > - .free = dma_npu_free, > > - .dma_supported = dma_npu_dma_supported, > > - .get_required_mask = dma_npu_get_required_mask, > > -}; > > - > > /* > > * Returns the PE assoicated with the PCI device of the given > > * NPU. Returns the linked pci device if pci_dev != NULL. > > @@ -270,10 +213,11 @@ static void pnv_npu_dma_set_32(struct pnv_ioda_pe *npe) > > rc = pnv_npu_set_window(npe, 0, gpe->table_group.tables[0]); > > > > /* > > - * We don't initialise npu_pe->tce32_table as we always use > > - * dma_npu_ops which are nops. > > + * NVLink devices use the same TCE table configuration as > > + * their parent device so drivers shouldn't be doing DMA > > + * operations directly on these devices. > > */ > > - set_dma_ops(&npe->pdev->dev, &dma_npu_ops); > > + set_dma_ops(&npe->pdev->dev, NULL); > > } > > > > /* > > -- > > 2.11.0 > > ---end quoted text---