[PATCH v4 09/11] dmaengine: dw: Initialize min_burst capability

From: Serge Semin
Date: Thu May 28 2020 - 18:28:25 EST


According to the DW APB DMAC data book the minimum burst transaction
length is 1 and it's true for any version of the controller since
isn't parametrised in the coreAssembler so can't be changed at the
IP-core synthesis stage. Let's initialise the min_burst member of the
DMA controller descriptor so the DMA clients could use it to properly
optimize the DMA requests.

Signed-off-by: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx>
Cc: Alexey Malahov <Alexey.Malahov@xxxxxxxxxxxxxxxxxxxx>
Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxxx
Cc: devicetree@xxxxxxxxxxxxxxx

---

Changelog v4:
- This is a new patch suggested by Andy.
---
drivers/dma/dw/core.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
index ceded21537e2..a8cebb1dbb68 100644
--- a/drivers/dma/dw/core.c
+++ b/drivers/dma/dw/core.c
@@ -1229,6 +1229,7 @@ int do_dma_probe(struct dw_dma_chip *chip)
dw->dma.device_issue_pending = dwc_issue_pending;

/* DMA capabilities */
+ dw->dma.min_burst = 1;
dw->dma.src_addr_widths = DW_DMA_BUSWIDTHS;
dw->dma.dst_addr_widths = DW_DMA_BUSWIDTHS;
dw->dma.directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV) |
--
2.26.2