[RFC PATCH v3 11/16] mmc: omap_hsmmc: limit max_segs with the EDMA DMAC
From: Matt Porter <hidden>
Date: 2012-10-18 13:27:51
Also in:
linux-devicetree, linux-mmc, linux-omap, linux-spi, lkml
Subsystem:
multimedia card (mmc), secure digital (sd) and sdio subsystem, omap hs mmc support, the rest · Maintainers:
Ulf Hansson, Linus Torvalds
The EDMA DMAC has a hardware limitation that prevents supporting scatter gather lists with any number of segments. Since the EDMA DMA Engine driver sets the maximum segments to 16, we do the same. TODO: this will be replaced once the DMA Engine API supports an API to query the DMAC's segment size limit. Signed-off-by: Matt Porter <redacted> --- drivers/mmc/host/omap_hsmmc.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
index b327cd0..52bab01 100644
--- a/drivers/mmc/host/omap_hsmmc.c
+++ b/drivers/mmc/host/omap_hsmmc.c@@ -1828,6 +1828,16 @@ static int __devinit omap_hsmmc_probe(struct platform_device *pdev) * as we want. */ mmc->max_segs = 1024; + /* Eventually we should get our max_segs limitation for EDMA by + * querying the dmaengine API */ + if (pdev->dev.of_node) { + struct device_node *parent = pdev->dev.of_node->parent; + struct device_node *node; + node = of_find_node_by_name(parent, "edma"); + if (node) + mmc->max_segs = 16; + } + mmc->max_blk_size = 512; /* Block Length at max can be 1024 */ mmc->max_blk_count = 0xFFFF; /* No. of Blocks is 16 bits */ mmc->max_req_size = mmc->max_blk_size * mmc->max_blk_count;
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1.7.9.5