From 23adfc77c22cb959ac84e08dc8a77bac656f1caa Mon Sep 17 00:00:00 2001 From: Aditya Garg Date: Fri, 7 Aug 2026 13:56:36 -0700 Subject: net: mana: Fall back to scattered pages for GDMA queues Each GDMA queue ring is one dma_alloc_coherent() of the whole ring size. Such high-order allocations fail first under memory fragmentation, so queue setup can fail with memory still free. The hardware does not need the ring physically contiguous: mana_gd_create_dma_region() already maps it as a list of MANA_PAGE_SIZE (4K) device addresses. Only the driver's linear CPU view needs contiguity, and it goes through mana_gd_ring_ptr() and mana_gd_ring_contig_avail(); change both to map offsets onto scattered pages. Add a fallback in mana_gd_alloc_memory(): data-path queues pass allow_scatter=true, so when the contiguous allocation fails the ring is backed by a vector of scattered PAGE_SIZE (order-0) coherent pages, presenting the same DMA page-list layout to the device. The HW channel bootstrap keeps allow_scatter=false, and the debugfs ring dumper reads scattered rings through the same helpers. Signed-off-by: Aditya Garg Link: https://patch.msgid.link/20260807210002.1695263-3-gargaditya@linux.microsoft.com Signed-off-by: Paolo Abeni --- include/net/mana/gdma.h | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/include/net/mana/gdma.h b/include/net/mana/gdma.h index 70a7f1fee5d3..9d57a0ea0e5e 100644 --- a/include/net/mana/gdma.h +++ b/include/net/mana/gdma.h @@ -241,6 +241,14 @@ struct gdma_mem_info { void *virt_addr; u64 length; + /* Scattered fallback: when @nr_pages > 0 the ring is that many + * PAGE_SIZE coherent allocations in @pages_va/@pages_dma, not + * @virt_addr/@dma_handle. + */ + void **pages_va; + dma_addr_t *pages_dma; + unsigned int nr_pages; + /* Allocated by the PF driver */ u64 dma_region_handle; }; @@ -516,6 +524,9 @@ int mana_gd_poll_cq(struct gdma_queue *cq, struct gdma_comp *comp, int num_cqe); void mana_gd_ring_cq(struct gdma_queue *cq, u8 arm_bit); +ssize_t mana_gd_read_ring(struct gdma_queue *q, char __user *buf, + size_t count, loff_t *pos); + int mana_schedule_serv_work(struct gdma_context *gc, enum gdma_eqe_type type); void mana_gd_ring_dim(struct gdma_queue *cq, u32 mod_usec, bool mod_usec_vld, @@ -672,6 +683,9 @@ enum { /* Driver supports dynamic interrupt moderation - DIM */ #define GDMA_DRV_CAP_FLAG_1_DYN_INTERRUPT_MODERATION BIT(28) +/* Driver supports non-contiguous queue buffers */ +#define GDMA_DRV_CAP_FLAG_1_NON_CONTIGUOUS_BUFFERS BIT(30) + #define GDMA_DRV_CAP_FLAGS1 \ (GDMA_DRV_CAP_FLAG_1_EQ_SHARING_MULTI_VPORT | \ GDMA_DRV_CAP_FLAG_1_NAPI_WKDONE_FIX | \ @@ -688,7 +702,8 @@ enum { GDMA_DRV_CAP_FLAG_1_HANDLE_STALL_SQ_RECOVERY | \ GDMA_DRV_CAP_FLAG_1_HWC_TIMEOUT_RECOVERY | \ GDMA_DRV_CAP_FLAG_1_EQ_MSI_UNSHARE_MULTI_VPORT | \ - GDMA_DRV_CAP_FLAG_1_DYN_INTERRUPT_MODERATION) + GDMA_DRV_CAP_FLAG_1_DYN_INTERRUPT_MODERATION | \ + GDMA_DRV_CAP_FLAG_1_NON_CONTIGUOUS_BUFFERS) #define GDMA_DRV_CAP_FLAGS2 0 @@ -1049,7 +1064,7 @@ void mana_gd_wq_ring_doorbell(struct gdma_context *gc, struct gdma_queue *queue); int mana_gd_alloc_memory(struct gdma_context *gc, unsigned int length, - struct gdma_mem_info *gmi); + struct gdma_mem_info *gmi, bool allow_scatter); void mana_gd_free_memory(struct gdma_mem_info *gmi); -- cgit v1.2.3