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dmaengine: dw-axi-dmac: report per-channel max_burst via device_caps

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The patch "dmaengine: dw-axi-dmac: add per-channel AXI burst length
support" programs ARLEN/AWLEN from the snps,axi-max-burst-len array but
still exposed a single max_burst value via dma_get_slave_caps(). As a
result all channels reported 8 even when limited to 4, leading to
warnings:

  dma dma2chan5: requested source burst length 8 exceeds supported 4

Add a .device_caps callback to return the correct per-channel max_burst.
This allows drivers like amba-pl011 to clamp burst lengths properly.

Fixes: 0e4e6a0c4f4e ("dmaengine: dw-axi-dmac: add per-channel AXI burst length support")
Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>
This commit is contained in:
Nicolai Buchwitz
2025-08-21 21:42:25 +02:00
committed by Dom Cobley
parent 79465ff1fe
commit 86bd72ff71
1 changed files with 11 additions and 1 deletions
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12
drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
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@@ -1476,6 +1476,16 @@ static int __maybe_unused axi_dma_runtime_resume(struct device *dev)
return axi_dma_resume(chip);
}
static void dw_axi_dma_device_caps(struct dma_chan *dchan,
struct dma_slave_caps *caps)
{
struct axi_dma_chan *chan = dchan_to_axi_dma_chan(dchan);
struct dw_axi_dma *dw = chan->chip->dw;
if (dw->hdata->restrict_axi_burst_len)
caps->max_burst = dw->hdata->axi_rw_burst_len[chan->id];
}
static bool dw_axi_dma_filter_fn(struct dma_chan *dchan, void *filter_param)
{
struct axi_dma_chan *chan = dchan_to_axi_dma_chan(dchan);
@@ -1746,7 +1756,7 @@ static int dw_probe(struct platform_device *pdev)
dma_cap_set(DMA_CYCLIC, dw->dma.cap_mask);
/* DMA capabilities */
dw->dma.max_burst = hdata->axi_rw_burst_len[0];
dw->dma.device_caps = dw_axi_dma_device_caps;
dw->dma.src_addr_widths = AXI_DMA_BUSWIDTHS;
dw->dma.dst_addr_widths = AXI_DMA_BUSWIDTHS;
dw->dma.directions = BIT(DMA_MEM_TO_MEM);