Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759272Ab3GRQrm (ORCPT ); Thu, 18 Jul 2013 12:47:42 -0400 Received: from arroyo.ext.ti.com ([192.94.94.40]:34295 "EHLO arroyo.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759171Ab3GRQrj (ORCPT ); Thu, 18 Jul 2013 12:47:39 -0400 From: Joel Fernandes To: Tony Lindgren , Sekhar Nori , Matt Porter , Grant Likely , Rob Herring , Vinod Koul , Mark Brown , Benoit Cousson , Russell King , Balaji TK , Gururaja Hebbar , Chris Ball CC: Jason Kridner , Mark Jackson , Devicetree Discuss , Linux OMAP List , Linux ARM Kernel List , Linux DaVinci Kernel List , Linux Kernel Mailing List , Linux Documentation List , Linux MMC List , Linux SPI Devel List , Arnd Bergmann , Joel Fernandes Subject: [PATCH 2/3] mmc: omap_hsmmc: set max_segs based on dma engine limits Date: Thu, 18 Jul 2013 11:46:40 -0500 Message-ID: <1374166001-31340-3-git-send-email-joelf@ti.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1374166001-31340-1-git-send-email-joelf@ti.com> References: <1374166001-31340-1-git-send-email-joelf@ti.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2022 Lines: 54 From: Matt Porter 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 : Allocate sg_limits structure in client driver, and have the dmaengine implementation fill it up] Signed-off-by: Matt Porter Acked-by: Tony Lindgren Signed-off-by: Joel Fernandes Cc: Mark Jackson --- 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-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/