The 64/32-bit DMA mask hackery in the EMAC driver is not actually necessary,
and is technically not accurate. The EMAC hardware is limted to a 45-bit
DMA address. Although no EMAC-enabled system can have that much DDR,
an IOMMU could possible provide a larger address. Rather than play games
with the DMA mappings, the driver should provide a correct value and
trust the DMA/IOMMU layers to do the right thing.
Signed-off-by: Timur Tabi <ti...@codeaurora.org>
---
drivers/net/ethernet/qualcomm/emac/emac.c | 17 ++++-------------
1 file changed, 4 insertions(+), 13 deletions(-)
diff --git a/drivers/net/ethernet/qualcomm/emac/emac.c
b/drivers/net/ethernet/qualcomm/emac/emac.c
index f477ba29c569..ee6f2d27502c 100644
--- a/drivers/net/ethernet/qualcomm/emac/emac.c
+++ b/drivers/net/ethernet/qualcomm/emac/emac.c
@@ -615,20 +615,11 @@ static int emac_probe(struct platform_device *pdev)
u32 reg;
int ret;
- /* The EMAC itself is capable of 64-bit DMA, so try that first. */
- ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
+ /* The TPD buffer address is limited to 45 bits. */
+ ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(45));
if (ret) {
- /* Some platforms may restrict the EMAC's address bus to less
- * then the size of DDR. In this case, we need to try a
- * smaller mask. We could try every possible smaller mask,
- * but that's overkill. Instead, just fall to 32-bit, which
- * should always work.
- */
- ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
- if (ret) {
- dev_err(&pdev->dev, "could not set DMA mask\n");
- return ret;
- }
+ dev_err(&pdev->dev, "could not set DMA mask\n");
+ return ret;
}
netdev = alloc_etherdev(sizeof(struct emac_adapter));
--
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm
Technologies, Inc. Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.
