Messages in this thread | | | Subject | Re: [PATCH] powerpc/npu-dma: Remove NPU DMA ops | From | Benjamin Herrenschmidt <> | Date | Wed, 31 Oct 2018 00:09:29 +1100 |
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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 <alistair@popple.id.au> > > --- > > 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---
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