From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755090Ab3AKFoq (ORCPT ); Fri, 11 Jan 2013 00:44:46 -0500 Received: from mail-qc0-f176.google.com ([209.85.216.176]:52653 "EHLO mail-qc0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755009Ab3AKFom (ORCPT ); Fri, 11 Jan 2013 00:44:42 -0500 From: Matt Porter To: Tony Lindgren , Sekhar Nori , Grant Likely , Mark Brown , Benoit Cousson , Russell King , Vinod Koul , Rob Landley , Chris Ball Cc: 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 , Dan Williams , Rob Herring Subject: [PATCH v4 09/14] mmc: omap_hsmmc: set max_segs based on dma engine limitations Date: Fri, 11 Jan 2013 00:48:45 -0500 Message-Id: <1357883330-5364-10-git-send-email-mporter@ti.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1357883330-5364-1-git-send-email-mporter@ti.com> References: <1357883330-5364-1-git-send-email-mporter@ti.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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