On Sat, Jul 21, 2012 at 01:22:40PM -0400, Mike Frysinger wrote:
On Friday 20 July 2012 17:50:33 Tom Rini wrote:
On 07/20/2012 02:47 PM, Mike Frysinger wrote:
On Friday 20 July 2012 07:31:47 Marek Vasut wrote:
Dear Mike Frysinger,
On Saturday 07 July 2012 23:08:14 Marek Vasut wrote:
+/* DEFINE_CACHE_ALIGN_BUFFER() is similar to ALLOC_CACHE_ALIGN_BUFFER, but it's purpose is to allow allocating aligned buffers outside of function scope. Usage of this macro shall be avoided or used with extreme care! */ +#define DEFINE_CACHE_ALIGN_BUFFER(type, name, size) + static char __##name[roundup(size * sizeof(type), ARCH_DMA_MINALIGN)] + __aligned(ARCH_DMA_MINALIGN); + static type *name = (type *)__##name;
how is this any different from doing: static __u8 foo[1234] __aligned(ARCH_DMA_MINALIGN);
Does __aligned() align both start of the buffer downwards and end of it upwards ?
it guarantees the start is aligned. i don't believe it does any tail padding.
that said, you've added just 1 consumer, but it uses in function scope, so i don't see why you had to define a new helper in the first place. the existing one would work fine shouldn't it ?
The rough outline of the problems are:
- We need to have buffers that are multiple of cache size, for clearing.
- Today we know ehci-hcd had a problem. We also know other drivers /
layers have problems, but they aren't as readily breakable.
That's why we put the macro in <common.h> rather than a USB header.
that wasn't the question. no one in the tree needs the new macro at all, regardless of what header it lives in. i guess the answer is that some code in the future (which hasn't been merged) might use it.
Er, between drivers/usb/host/ehci-hcd.c and drivers/usb/eth/smsc95xx.c the three new macros are used today.