[PATCH net-next 3/4] net: ipa: fix table alignment requirement
From: Alex Elder <hidden>
Date: 2021-03-17 22:30:48
Also in:
lkml
Subsystem:
networking drivers, qcom ipa driver, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Alex Elder, Linus Torvalds
We currently have a build-time check to ensure that the minimum DMA allocation alignment satisfies the constraint that IPA filter and route tables must point to rules that are 128-byte aligned. But what's really important is that the actual allocated DMA memory has that alignment, even if the minimum is smaller than that. Remove the BUILD_BUG_ON() call checking against minimim DMA alignment and instead verify at rutime that the allocated memory is properly aligned. Signed-off-by: Alex Elder <redacted> --- drivers/net/ipa/ipa_table.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/drivers/net/ipa/ipa_table.c b/drivers/net/ipa/ipa_table.c
index dd07fe9dd87a3..988f2c2886b95 100644
--- a/drivers/net/ipa/ipa_table.c
+++ b/drivers/net/ipa/ipa_table.c@@ -118,14 +118,6 @@ /* Check things that can be validated at build time. */ static void ipa_table_validate_build(void) { - /* IPA hardware accesses memory 128 bytes at a time. Addresses - * referred to by entries in filter and route tables must be - * aligned on 128-byte byte boundaries. The only rule address - * ever use is the "zero rule", and it's aligned at the base - * of a coherent DMA allocation. - */ - BUILD_BUG_ON(ARCH_DMA_MINALIGN % IPA_TABLE_ALIGN); - /* Filter and route tables contain DMA addresses that refer * to filter or route rules. But the size of a table entry * is 64 bits regardless of what the size of an AP DMA address
@@ -665,6 +657,18 @@ int ipa_table_init(struct ipa *ipa) if (!virt) return -ENOMEM; + /* We put the "zero rule" at the base of our table area. The IPA + * hardware requires rules to be aligned on a 128-byte boundary. + * Make sure the allocation satisfies this constraint. + */ + if (addr % IPA_TABLE_ALIGN) { + dev_err(dev, "table address %pad not %u-byte aligned\n", + &addr, IPA_TABLE_ALIGN); + dma_free_coherent(dev, size, virt, addr); + + return -ERANGE; + } + ipa->table_virt = virt; ipa->table_addr = addr;
--
2.27.0