From: Matt Porter <mporter@xxxxxx> 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 <joelf@xxxxxx>: Allocate sg_limits structure in client driver, and have the dmaengine implementation fill it up] Signed-off-by: Matt Porter <mporter@xxxxxx> Acked-by: Tony Lindgren <tony@xxxxxxxxxxx> Signed-off-by: Joel Fernandes <joelf@xxxxxx> Cc: Mark Jackson <mpfj-list@xxxxxxxxxxxxx> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
