[PATCH 42/44] powerpc/cell: use the dma_supported method for ops switching
From: benh@kernel.crashing.org (Benjamin Herrenschmidt)
Date: 2017-06-17 20:51:54
Also in:
dri-devel, linux-iommu, linux-mips, linux-s390, linux-samsung-soc, linux-sh, linux-tegra, linuxppc-dev, lkml, netdev, sparclinux
On Fri, 2017-06-16 at 20:10 +0200, Christoph Hellwig wrote:
Besides removing the last instance of the set_dma_mask method this also reduced the code duplication.
What is your rationale here ? (I have missed patch 0 it seems). dma_supported() was supposed to be pretty much a "const" function simply informing whether a given setup is possible. Having it perform an actual switch of ops seems to be pushing it... What if a driver wants to test various dma masks and then pick one ? Where does the API documents that if a driver calls dma_supported() it then *must* set the corresponding mask and use that ? I don't like a function that is a "boolean query" like this one to have such a major side effect.
From an API standpoint, dma_set_mask() is when the mask is established,
and thus when the ops switch should happen. Ben.
quoted hunk ↗ jump to hunk
Signed-off-by: Christoph Hellwig <hch@lst.de> --- arch/powerpc/platforms/cell/iommu.c | 25 +++++++++---------------- 1 file changed, 9 insertions(+), 16 deletions(-)diff --git a/arch/powerpc/platforms/cell/iommu.c b/arch/powerpc/platforms/cell/iommu.c index 497bfbdbd967..29d4f96ed33e 100644 --- a/arch/powerpc/platforms/cell/iommu.c +++ b/arch/powerpc/platforms/cell/iommu.c@@ -644,20 +644,14 @@ static void dma_fixed_unmap_sg(struct device *dev, struct scatterlist *sg, direction, attrs); } -static int dma_fixed_dma_supported(struct device *dev, u64 mask) -{ - return mask == DMA_BIT_MASK(64); -} - -static int dma_set_mask_and_switch(struct device *dev, u64 dma_mask); +static int dma_suported_and_switch(struct device *dev, u64 dma_mask); static const struct dma_map_ops dma_iommu_fixed_ops = { .alloc = dma_fixed_alloc_coherent, .free = dma_fixed_free_coherent, .map_sg = dma_fixed_map_sg, .unmap_sg = dma_fixed_unmap_sg, - .dma_supported = dma_fixed_dma_supported, - .set_dma_mask = dma_set_mask_and_switch, + .dma_supported = dma_suported_and_switch, .map_page = dma_fixed_map_page, .unmap_page = dma_fixed_unmap_page, .mapping_error = dma_iommu_mapping_error,@@ -952,11 +946,8 @@ static u64 cell_iommu_get_fixed_address(struct device *dev) return dev_addr; } -static int dma_set_mask_and_switch(struct device *dev, u64 dma_mask) +static int dma_suported_and_switch(struct device *dev, u64 dma_mask) { - if (!dev->dma_mask || !dma_supported(dev, dma_mask)) - return -EIO; - if (dma_mask == DMA_BIT_MASK(64) && cell_iommu_get_fixed_address(dev) != OF_BAD_ADDR) { u64 addr = cell_iommu_get_fixed_address(dev) +@@ -965,14 +956,16 @@ static int dma_set_mask_and_switch(struct device *dev, u64 dma_mask) dev_dbg(dev, "iommu: fixed addr = %llx\n", addr); set_dma_ops(dev, &dma_iommu_fixed_ops); set_dma_offset(dev, addr); - } else { + return 1; + } + + if (dma_iommu_dma_supported(dev, dma_mask)) { dev_dbg(dev, "iommu: not 64-bit, using default ops\n"); set_dma_ops(dev, get_pci_dma_ops()); cell_dma_dev_setup(dev); + return 1; } - *dev->dma_mask = dma_mask; - return 0; }@@ -1127,7 +1120,7 @@ static int __init cell_iommu_fixed_mapping_init(void) cell_iommu_setup_window(iommu, np, dbase, dsize, 0); } - dma_iommu_ops.set_dma_mask = dma_set_mask_and_switch; + dma_iommu_ops.dma_supported = dma_suported_and_switch; set_pci_dma_ops(&dma_iommu_ops); return 0;