4.16-stable review patch. If anyone has any objections, please let me know.
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From: Ard Biesheuvel ard.biesheuvel@linaro.org
[ Upstream commit 312564269535892cc082bc80592150cd1f5e8ec3 ]
The netsec network controller IP can drive 64 address bits for DMA, and the DMA mask is set accordingly in the driver. However, the SynQuacer SoC, which is the only silicon incorporating this IP at the moment, integrates this IP in a manner that leaves address bits [63:40] unconnected.
Up until now, this has not resulted in any problems, given that the DDR controller doesn't decode those bits to begin with. However, recent firmware updates for platforms incorporating this SoC allow the IOMMU to be enabled, which does decode address bits [47:40], and allocates top down from the IOVA space, producing DMA addresses that have bits set that have been left unconnected.
Both the DT and ACPI (IORT) descriptions of the platform take this into account, and only describe a DMA address space of 40 bits (using either dma-ranges DT properties, or DMA address limits in IORT named component nodes). However, even though our IOMMU and bus layers may take such limitations into account by setting a narrower DMA mask when creating the platform device, the netsec probe() entrypoint follows the common practice of setting the DMA mask uncondionally, according to the capabilities of the IP block itself rather than to its integration into the chip.
It is currently unclear what the correct fix is here. We could hack around it by only setting the DMA mask if it deviates from its default value of DMA_BIT_MASK(32). However, this makes it impossible for the bus layer to use DMA_BIT_MASK(32) as the bus limit, and so it appears that a more comprehensive approach is required to take DMA limits imposed by the SoC as a whole into account.
In the mean time, let's limit the DMA mask to 40 bits. Given that there is currently only one SoC that incorporates this IP, this is a reasonable approach that can be backported to -stable and buys us some time to come up with a proper fix going forward.
Fixes: 533dd11a12f6 ("net: socionext: Add Synquacer NetSec driver") Cc: Robin Murphy robin.murphy@arm.com Cc: Jassi Brar jaswinder.singh@linaro.org Cc: Masahisa Kojima masahisa.kojima@linaro.org Cc: Ilias Apalodimas ilias.apalodimas@linaro.org Signed-off-by: Ard Biesheuvel ard.biesheuvel@linaro.org Reviewed-by: Robin Murphy robin.murphy@arm.com Acked-by: Jassi Brar jaswinder.singh@linaro.org Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/ethernet/socionext/netsec.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/net/ethernet/socionext/netsec.c +++ b/drivers/net/ethernet/socionext/netsec.c @@ -1674,8 +1674,8 @@ static int netsec_probe(struct platform_ if (ret) goto unreg_napi;
- if (dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64))) - dev_warn(&pdev->dev, "Failed to enable 64-bit DMA\n"); + if (dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(40))) + dev_warn(&pdev->dev, "Failed to set DMA mask\n");
ret = register_netdev(ndev); if (ret) {