77 lines
2.4 KiB
Diff
77 lines
2.4 KiB
Diff
From 6077fbf31d4263222eb1815f1c4edf67e90a3434 Mon Sep 17 00:00:00 2001
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From: Matt Porter <mporter@ti.com>
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Date: Wed, 6 Mar 2013 19:56:06 +0000
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Subject: [PATCH 02/13] dma: edma: add device_slave_sg_limits() support
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Implement device_slave_sg_limits().
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EDMA has a finite set of PaRAM slots available for linking a
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multi-segment SG transfer. In order to prevent any one channel
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from consuming all PaRAM slots to fulfill a large SG transfer,
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the driver reports a static per-channel max number of SG segments
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it will handle.
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The maximum size of an SG segment is limited by the addr_width
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and maxburst of a given transfer request. These values are
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provided by the client driver and used to calculate and return
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the maximum segment length.
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Signed-off-by: Matt Porter <mporter@ti.com>
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Signed-off-by: Joel A Fernandes <joelagnel@ti.com>
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---
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drivers/dma/edma.c | 17 +++++++++++++++++
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1 file changed, 17 insertions(+)
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diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
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index 5f3e532..e008ed2 100644
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--- a/drivers/dma/edma.c
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+++ b/drivers/dma/edma.c
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@@ -70,6 +70,7 @@ struct edma_chan {
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bool alloced;
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int slot[EDMA_MAX_SLOTS];
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struct dma_slave_config cfg;
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+ struct dma_slave_sg_limits sg_limits;
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};
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struct edma_cc {
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@@ -462,6 +463,20 @@ static void edma_issue_pending(struct dma_chan *chan)
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spin_unlock_irqrestore(&echan->vchan.lock, flags);
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}
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+static struct dma_slave_sg_limits
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+*edma_get_slave_sg_limits(struct dma_chan *chan,
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+ enum dma_slave_buswidth addr_width,
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+ u32 maxburst)
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+{
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+ struct edma_chan *echan;
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+
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+ echan = to_edma_chan(chan);
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+ echan->sg_limits.max_seg_len =
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+ (SZ_64K - 1) * addr_width * maxburst;
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+
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+ return &echan->sg_limits;
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+}
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+
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static size_t edma_desc_size(struct edma_desc *edesc)
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{
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int i;
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@@ -521,6 +536,7 @@ static void __init edma_chan_init(struct edma_cc *ecc,
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echan->ch_num = EDMA_CTLR_CHAN(ecc->ctlr, i);
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echan->ecc = ecc;
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echan->vchan.desc_free = edma_desc_free;
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+ echan->sg_limits.max_seg_nr = MAX_NR_SG;
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vchan_init(&echan->vchan, dma);
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@@ -537,6 +553,7 @@ static void edma_dma_init(struct edma_cc *ecc, struct dma_device *dma,
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dma->device_alloc_chan_resources = edma_alloc_chan_resources;
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dma->device_free_chan_resources = edma_free_chan_resources;
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dma->device_issue_pending = edma_issue_pending;
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+ dma->device_slave_sg_limits = edma_get_slave_sg_limits;
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dma->device_tx_status = edma_tx_status;
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dma->device_control = edma_control;
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dma->dev = dev;
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--
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1.8.2.1
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