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_channel_caps() API. If the nr_segs capability is present, the value is used to configure mmc->max_segs appropriately. Signed-off-by: Matt Porter <mporter@xxxxxx> --- drivers/mmc/host/omap_hsmmc.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c index e79b12d..f74bd69 100644 --- a/drivers/mmc/host/omap_hsmmc.c +++ b/drivers/mmc/host/omap_hsmmc.c @@ -1769,6 +1769,7 @@ 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 dmaengine_chan_caps *dma_chan_caps; struct pinctrl *pinctrl; match = of_match_device(of_match_ptr(omap_mmc_of_match), &pdev->dev); @@ -1935,6 +1936,11 @@ static int omap_hsmmc_probe(struct platform_device *pdev) goto err_irq; } + /* Some DMA Engines only handle a limited number of SG segments */ + dma_chan_caps = dma_get_channel_caps(host->rx_chan, DMA_DEV_TO_MEM); + if (dma_chan_caps && dma_chan_caps->seg_nr) + mmc->max_segs = dma_chan_caps->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
