[PATCH 1/2] MIPS: Octeon: size the swiotlb for a modular OHCI platform driver

[Orgad Shaneh]

plat_swiotlb_setup() raises the swiotlb to 64 MB on OCTEON II with
memory above 4 GB, because that OHCI can only DMA to 32 bits. The test
is "#ifdef CONFIG_USB_OHCI_HCD_PLATFORM", which is false when the driver
is a module - the usual way to build it - so the bump is silently
skipped.

What is left depends on the rest of the function: with PCI enabled the
"memory past the BAR1 hole" branch happens to ask for the same 64 MB,
but with CONFIG_PCI off - which is normal on these SoCs when no PCI
devices are wired - swiotlbsize stays at the PAGE_SIZE it was
initialised to. A full- or low-speed device on an OCTEON II board with
more than 4 GB of RAM then has no bounce buffer to speak of.

Use IS_ENABLED() so a modular OHCI gets the same sizing as a built-in
one. Seen on a CN6635 board with 8 GB of RAM and
CONFIG_USB_OHCI_HCD_PLATFORM=m.

Fixes: a8667d706dfa ("MIPS: OCTEON: dma-octeon: fix OHCI USB config check")
Assisted-by: Claude:claude-opus-5
Signed-off-by: Orgad Shaneh <orgads@xxxxxxxxx>
---
diff --git a/arch/mips/cavium-octeon/dma-octeon.c b/arch/mips/cavium-octeon/dma-octeon.c
--- a/arch/mips/cavium-octeon/dma-octeon.c
+++ b/arch/mips/cavium-octeon/dma-octeon.c
@@ -228,7 +228,7 @@ void __init plat_swiotlb_setup(void)
 		swiotlbsize = 64 * (1<<20);
 	}
 #endif
-#ifdef CONFIG_USB_OHCI_HCD_PLATFORM
+#if IS_ENABLED(CONFIG_USB_OHCI_HCD_PLATFORM)
 	/* OCTEON II ohci is only 32-bit. */
 	if (OCTEON_IS_OCTEON2() && max_addr >= 0x100000000ul)
 		swiotlbsize = 64 * (1<<20);
-- 
2.47.0