From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joel Fernandes Subject: [PATCH 3/3] dma: edma: add device_slave_sg_limits() support Date: Thu, 18 Jul 2013 11:46:41 -0500 Message-ID: <1374166001-31340-4-git-send-email-joelf@ti.com> References: <1374166001-31340-1-git-send-email-joelf@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Linux DaVinci Kernel List , Arnd Bergmann , Mark Jackson , Joel Fernandes , Devicetree Discuss , Linux Documentation List , Linux MMC List , Linux Kernel Mailing List , Jason Kridner , Linux SPI Devel List , Linux OMAP List , Linux ARM Kernel List 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 Return-path: In-Reply-To: <1374166001-31340-1-git-send-email-joelf-l0cyMroinI0@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: Errors-To: davinci-linux-open-source-bounces+gld-davinci-linux-open-source=gmane.org-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org List-Id: linux-spi.vger.kernel.org From: Matt Porter Implement device_slave_sg_limits(). EDMA has a finite set of PaRAM slots available for linking a multi-segment SG transfer. In order to prevent any one channel from consuming all PaRAM slots to fulfill a large SG transfer, the driver reports a static per-channel max number of SG segments it will handle. The maximum size of an SG segment is limited by the addr_width and maxburst of a given transfer request. These values are provided by the client driver and used to calculate and return the maximum segment length. [Joel Fernandes : Changes for filling sg_limits by DMAEngine implementation and allocating in client, channel parameter is unused in this implementation as all channels have the same capability] Signed-off-by: Matt Porter Signed-off-by: Joel Fernandes Cc: Mark Jackson --- drivers/dma/edma.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c index 5f3e532..964de26 100644 --- a/drivers/dma/edma.c +++ b/drivers/dma/edma.c @@ -462,6 +462,19 @@ static void edma_issue_pending(struct dma_chan *chan) spin_unlock_irqrestore(&echan->vchan.lock, flags); } +static inline int edma_get_slave_sg_limits(struct dma_chan *chan, + enum dma_slave_buswidth addr_width, + u32 maxburst, + struct dma_slave_sg_limits *sg_limits) +{ + if (!sg_limits) + return -EINVAL; + sg_limits->max_seg_nr = MAX_NR_SG; + sg_limits->max_seg_len = + (SZ_64K - 1) * addr_width * maxburst; + return 0; +} + static size_t edma_desc_size(struct edma_desc *edesc) { int i; @@ -537,6 +550,7 @@ static void edma_dma_init(struct edma_cc *ecc, struct dma_device *dma, dma->device_alloc_chan_resources = edma_alloc_chan_resources; dma->device_free_chan_resources = edma_free_chan_resources; dma->device_issue_pending = edma_issue_pending; + dma->device_slave_sg_limits = edma_get_slave_sg_limits; dma->device_tx_status = edma_tx_status; dma->device_control = edma_control; dma->dev = dev; -- 1.7.9.5