usb: device_next: Respect granularity in UDC buf pool define (0f419505) · Commits · Wenxi XU / zephyr

Round up buffer size used in UDC_BUF_POOL_DEFINE() to respect the required buffer granularity. The issue was observed with UAC2 explicit feedback data, but the problem applies to any UDC_BUF_POOL_DEFINE() use. In order for every buffer returned by UDC_BUF_POOL_DEFINE() to be both aligned and to have required granurality, it is required to allocate the buffers for ROUND_UP(size, LCM(UDC_BUF_GRANULARITY, UDC_BUF_ALIGN)). Because we do not have Least Common Multiple nor Greatest Common Divisor compile time macros, assume that granularity is multiple of alignment. Validate the assumption with a build time assert. When we get a target where this assumption fails we would have to come up with a solution to compute LCM and/or GCD at compile time. Signed-off-by:

Tomasz Moń <tomasz.mon@nordicsemi.no>

include/zephyr/drivers/usb/udc_buf.h

+4 −2

Original line number	Diff line number	Diff line
		@@ -132,15 +132,17 @@ extern const struct net_buf_data_cb net_buf_dma_cb;
		*/
		#define UDC_BUF_POOL_DEFINE(pname, count, size, ud_size, fdestroy) \
		_NET_BUF_ARRAY_DEFINE(pname, count, ud_size); \
		BUILD_ASSERT((UDC_BUF_GRANULARITY) % (UDC_BUF_ALIGN) == 0, \
		"Code assumes granurality is multiple of alignment"); \
		static uint8_t __nocache __aligned(UDC_BUF_ALIGN) \
		net_buf_data_##pname[count][size]; \
		net_buf_data_##pname[count][ROUND_UP(size, UDC_BUF_GRANULARITY)];\
		static const struct net_buf_pool_fixed net_buf_fixed_##pname = { \
		.data_pool = (uint8_t *)net_buf_data_##pname, \
		}; \
		static const struct net_buf_data_alloc net_buf_fixed_alloc_##pname = { \
		.cb = &net_buf_fixed_cb, \
		.alloc_data = (void *)&net_buf_fixed_##pname, \
		.max_alloc_size = size, \
		.max_alloc_size = ROUND_UP(size, UDC_BUF_GRANULARITY), \
		}; \
		static STRUCT_SECTION_ITERABLE(net_buf_pool, pname) = \
		NET_BUF_POOL_INITIALIZER(pname, &net_buf_fixed_alloc_##pname, \

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