linux-kernel - [PATCH] dma: edma: add device_slave

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Date:	Tue, 23 Jul 2013 11:43:24 -0500
From:	Joel Fernandes <joelf@...com>
To:	Vinod Koul <vinod.koul@...el.com>, Dan Williams <djbw@...com>
CC:	Tony Lindgren <tony@...mide.com>, Sekhar Nori <nsekhar@...com>,
	Arnd Bergmann <arnd@...db.de>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Rajendra Nayak <rnayak@...com>,
	Lokesh Vutla <lokeshvutla@...com>, Balaji TK <balajitk@...com>,
	Matt Porter <matt@...orter.com>,
	Rob Herring <rob.herring@...xeda.com>,
	Jason Kridner <jkridner@...gleboard.org>,
	Koen Kooi <koen@...gleboard.org>,
	Linux OMAP List <linux-omap@...r.kernel.org>,
	Linux ARM Kernel List <linux-arm-kernel@...ts.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux MMC List <linux-mmc@...r.kernel.org>,
	Joel Fernandes <joelf@...com>
Subject: [PATCH] dma: edma: add device_slave_caps() support

Implement device_slave_caps(). EDMA has a limited number of slots.
Slave drivers such as omap_hsmmc will query the driver to make
sure they don't pass in more than these many scatter segments.

Signed-off-by: Joel Fernandes <joelf@...com>
---
Vinod, or Dan- If this patch looks ok, can you please merge in for
-rc cycle? This patch is required to fix MMC support on AM33xx. This
patch is blocking 3 other patches which fix various MMC things. Thanks!

Notes:
(1) this approach is temporary and only for -rc cycle to fix MMC on
AM335x. It will be replace by the RFC series in future kernels:
http://www.spinics.net/lists/arm-kernel/msg260094.html

(2) Patch depends Vinod's patch at:
http://permalink.gmane.org/gmane.linux.kernel/1525112

 drivers/dma/edma.c |    9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index 7222cbe..81d5429 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -517,6 +517,14 @@ static void edma_issue_pending(struct dma_chan *chan)
 	spin_unlock_irqrestore(&echan->vchan.lock, flags);
 }
 
+static inline int edma_slave_caps(struct dma_chan *chan,
+	struct dma_slave_caps *caps)
+{
+	caps->max_sg_nr = MAX_NR_SG;
+
+	return 0;
+}
+
 static size_t edma_desc_size(struct edma_desc *edesc)
 {
 	int i;
@@ -594,6 +602,7 @@ static void edma_dma_init(struct edma_cc *ecc, struct dma_device *dma,
 	dma->device_issue_pending = edma_issue_pending;
 	dma->device_tx_status = edma_tx_status;
 	dma->device_control = edma_control;
+	dma->device_slave_caps = edma_slave_caps;
 	dma->dev = dev;
 
 	INIT_LIST_HEAD(&dma->channels);
-- 
1.7.9.5

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