From 6077fbf31d4263222eb1815f1c4edf67e90a3434 Mon Sep 17 00:00:00 2001 From: Matt Porter Date: Wed, 6 Mar 2013 19:56:06 +0000 Subject: [PATCH 02/13] dma: edma: add device_slave_sg_limits() support 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. Signed-off-by: Matt Porter Signed-off-by: Joel A Fernandes --- drivers/dma/edma.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c index 5f3e532..e008ed2 100644 --- a/drivers/dma/edma.c +++ b/drivers/dma/edma.c @@ -70,6 +70,7 @@ struct edma_chan { bool alloced; int slot[EDMA_MAX_SLOTS]; struct dma_slave_config cfg; + struct dma_slave_sg_limits sg_limits; }; struct edma_cc { @@ -462,6 +463,20 @@ static void edma_issue_pending(struct dma_chan *chan) spin_unlock_irqrestore(&echan->vchan.lock, flags); } +static struct dma_slave_sg_limits +*edma_get_slave_sg_limits(struct dma_chan *chan, + enum dma_slave_buswidth addr_width, + u32 maxburst) +{ + struct edma_chan *echan; + + echan = to_edma_chan(chan); + echan->sg_limits.max_seg_len = + (SZ_64K - 1) * addr_width * maxburst; + + return &echan->sg_limits; +} + static size_t edma_desc_size(struct edma_desc *edesc) { int i; @@ -521,6 +536,7 @@ static void __init edma_chan_init(struct edma_cc *ecc, echan->ch_num = EDMA_CTLR_CHAN(ecc->ctlr, i); echan->ecc = ecc; echan->vchan.desc_free = edma_desc_free; + echan->sg_limits.max_seg_nr = MAX_NR_SG; vchan_init(&echan->vchan, dma); @@ -537,6 +553,7 @@ 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; -- 1.8.2.1