From: Matt Porter <mpor...@ti.com>
The EDMA DMAC has a hardware limitation that prevents supporting
scatter gather lists with any number of segments. The DMA Engine
API reports the maximum number of segments a channel can support
via the optional dma_get_slave_sg_limits() API. If the max_nr_segs
limit is present, the value is used to configure mmc->max_segs
appropriately.
[Joel Fernandes <jo...@ti.com>: Allocate sg_limits structure in
client driver, and have the dmaengine implementation fill it up]
Signed-off-by: Matt Porter <mpor...@ti.com>
Acked-by: Tony Lindgren <t...@atomide.com>
Signed-off-by: Joel Fernandes <jo...@ti.com>
Cc: Mark Jackson <mpfj-l...@newflow.co.uk>
---
drivers/mmc/host/omap_hsmmc.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
index eccedc7..b723095 100644
--- a/drivers/mmc/host/omap_hsmmc.c
+++ b/drivers/mmc/host/omap_hsmmc.c
@@ -1776,6 +1776,7 @@ static int omap_hsmmc_probe(struct platform_device *pdev)
const struct of_device_id *match;
dma_cap_mask_t mask;
unsigned tx_req, rx_req;
+ struct dma_slave_sg_limits dma_sg_limits;
struct pinctrl *pinctrl;
match = of_match_device(of_match_ptr(omap_mmc_of_match), &pdev->dev);
@@ -1952,6 +1953,14 @@ static int omap_hsmmc_probe(struct platform_device *pdev)
goto err_irq;
}
+ /* Some DMA Engines only handle a limited number of SG segments */
+ ret = dma_get_slave_sg_limits(host->rx_chan,
+ DMA_SLAVE_BUSWIDTH_4_BYTES,
+ mmc->max_blk_size / 4,
+ &dma_sg_limits);
+ if (!ret && dma_sg_limits.max_seg_nr)
+ mmc->max_segs = dma_sg_limits.max_seg_nr;
+
/* Request IRQ for MMC operations */
ret = request_irq(host->irq, omap_hsmmc_irq, 0,
mmc_hostname(mmc), host);
--
1.7.9.5
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