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dmaengine: dw-axi-dmac: Honour snps,block-size

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The snps,block-size DT property declares the maximum block size for each
channel of the dw-axi-dmac. However, the driver ignores these when
setting max_seg_size and uses MAX_BLOCK_SIZE (4096) instead.

To take advantage of the efficiencies of larger blocks, calculate the
minimum block size across all channels and use that instead.

See: https://github.com/raspberrypi/linux/issues/6256

Signed-off-by: Phil Elwell <phil@raspberrypi.com>
This commit is contained in:
Phil Elwell
2024-07-10 14:47:17 +01:00
committed by Dom Cobley
parent f8c0c47eef
commit a031979b5b
1 changed files with 14 additions and 1 deletions
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15
drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
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@@ -1563,6 +1563,7 @@ static int dw_probe(struct platform_device *pdev)
struct dw_axi_dma *dw;
struct dw_axi_dma_hcfg *hdata;
struct reset_control *resets;
unsigned int max_seg_size;
unsigned int flags;
u32 i;
int ret;
@@ -1673,9 +1674,21 @@ static int dw_probe(struct platform_device *pdev)
* Synopsis DesignWare AxiDMA datasheet mentioned Maximum
* supported blocks is 1024. Device register width is 4 bytes.
* Therefore, set constraint to 1024 * 4.
* However, if all channels specify a greater value, use that instead.
*/
dw->dma.dev->dma_parms = &dw->dma_parms;
dma_set_max_seg_size(&pdev->dev, MAX_BLOCK_SIZE);
max_seg_size = UINT_MAX;
for (i = 0; i < dw->hdata->nr_channels; i++) {
unsigned int block_size = chip->dw->hdata->block_size[i];
if (!block_size)
block_size = MAX_BLOCK_SIZE;
max_seg_size = min(block_size, max_seg_size);
}
dma_set_max_seg_size(&pdev->dev, max_seg_size);
platform_set_drvdata(pdev, chip);
pm_runtime_enable(chip->dev);