kernel/git/next/linux-next.git/drivers/dma/switchtec_dma.c, branch master

dmaengine: switchtec-dma: fix FIELD_GET misuse when programming SE threshold

2026-06-30T11:22:11+00:00

FIELD_GET(SE_THRESH_MASK, thresh) extracts bits [31:23] from thresh and right-shifts them, which is the inverse of the intended operation. Since thresh is derived from se_buf_len / 2 (at most 255), bits [31:23] are always zero, so the SE threshold is never actually programmed into the register. Use FIELD_PREP() instead to correctly left-shift thresh into bits [31:23] of the valid_en_se register, consistent with the FIELD_PREP usage for the perf tuner config just above. Fixes: 30eba9df76ad ("dmaengine: switchtec-dma: Implement hardware initialization and cleanup") Signed-off-by: David Carlier Review-by: Logan Gunthorpe Reviewed-by: Frank Li Link: https://patch.msgid.link/20260317083252.13224-1-devnexen@gmail.com Signed-off-by: Vinod Koul

dmaengine: switchtec-dma: Implement descriptor submission

2026-03-09T07:28:22+00:00

On prep, a spin lock is taken and the next entry in the circular buffer is filled. On submit, the spin lock just needs to be released as the requests are already pending. When switchtec_dma_issue_pending() is called, the sq_tail register is written to indicate there are new jobs for the dma engine to start on. Pause and resume operations are implemented by writing to a control register. Signed-off-by: Kelvin Cao Co-developed-by: George Ge Signed-off-by: George Ge Reviewed-by: Christoph Hellwig Signed-off-by: Logan Gunthorpe Link: https://patch.msgid.link/20260302210419.3656-4-logang@deltatee.com Signed-off-by: Vinod Koul

dmaengine: switchtec-dma: Implement hardware initialization and cleanup

2026-03-09T07:28:22+00:00

Initialize the hardware and create the dma channel queues. Signed-off-by: Kelvin Cao Co-developed-by: George Ge Signed-off-by: George Ge Reviewed-by: Christoph Hellwig Reviewed-by: Frank Li Signed-off-by: Logan Gunthorpe Link: https://patch.msgid.link/20260302210419.3656-3-logang@deltatee.com Signed-off-by: Vinod Koul

dmaengine: switchtec-dma: Introduce Switchtec DMA engine skeleton

2026-03-09T07:28:22+00:00

Some Switchtec Switches can expose DMA engines via extra PCI functions on the upstream ports. At most one such function can be supported on each upstream port. Each function can have one or more DMA channels. This patch is just the core PCI driver skeleton and dma engine registration. Signed-off-by: Kelvin Cao Co-developed-by: George Ge Signed-off-by: George Ge Reviewed-by: Christoph Hellwig Reviewed-by: Frank Li Signed-off-by: Logan Gunthorpe Link: https://patch.msgid.link/20260302210419.3656-2-logang@deltatee.com Signed-off-by: Vinod Koul