Paul Burton 0d0e14770d MIPS: Make (UN)CAC_ADDR() PHYS_OFFSET-agnostic ... Converting an address between cached & uncached (typically addresses in (c)kseg0 & (c)kseg1 or 2 xkphys regions) should not depend upon PHYS_OFFSET in any way - we're converting from a virtual address in one unmapped region to a virtual address in another unmapped region. For some reason our CAC_ADDR() & UNCAC_ADDR() macros make use of PAGE_OFFSET, which typically includes PHYS_OFFSET. This means that platforms with a non-zero PHYS_OFFSET typically have to workaround miscalculation by these 2 macros by also defining UNCAC_BASE to a value that isn't really correct. It appears that an attempt has previously been made to address this with commit 3f4579252aa1 ("MIPS: make CAC_ADDR and UNCAC_ADDR account for PHYS_OFFSET") which was later undone by commit ed3ce16c3d ("Revert "MIPS: make CAC_ADDR and UNCAC_ADDR account for PHYS_OFFSET"") which also introduced the ar7 workaround. That attempt at a fix was roughly equivalent, but essentially caused the CAC_ADDR() & UNCAC_ADDR() macros to cancel out PHYS_OFFSET by adding & then subtracting it again. In his revert Leonid is correct that using PHYS_OFFSET makes no sense in the context of these macros, but appears to have missed its inclusion via PAGE_OFFSET which means PHYS_OFFSET actually had an effect after the revert rather than before it. Here we fix this by modifying CAC_ADDR() & UNCAC_ADDR() to stop using PAGE_OFFSET (& thus PHYS_OFFSET), instead using __pa() & __va() along with UNCAC_BASE. For UNCAC_ADDR(), __pa() will convert a cached address to a physical address which we can simply use as an offset from UNCAC_BASE to obtain an address in the uncached region. For CAC_ADDR() we can undo the effect of UNCAC_ADDR() by subtracting UNCAC_BASE and using __va() on the result. With this change made, remove definitions of UNCAC_BASE from the ar7 & pic32 platforms which appear to have defined them only to workaround this problem. Signed-off-by: Paul Burton <paul.burton@mips.com> References: 3f4579252aa1 ("MIPS: make CAC_ADDR and UNCAC_ADDR account for PHYS_OFFSET") References: ed3ce16c3d ("Revert "MIPS: make CAC_ADDR and UNCAC_ADDR account for PHYS_OFFSET"") Patchwork: https://patchwork.linux-mips.org/patch/20046/ Cc: Florian Fainelli <f.fainelli@gmail.com> Cc: James Hogan <jhogan@kernel.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org Cc: Vladimir Kondratiev <vladimir.kondratiev@intel.com>		2018-07-30 10:27:20 -07:00
..
ar7.h	MIPS: Remove all the uses of custom gpio.h	2015-09-03 12:08:02 +02:00
irq.h	MIPS: Whitespace cleanup.	2013-02-01 10:00:22 +01:00
prom.h
spaces.h	MIPS: Make (UN)CAC_ADDR() PHYS_OFFSET-agnostic	2018-07-30 10:27:20 -07:00