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174 lines
4.9 KiB
Diff
174 lines
4.9 KiB
Diff
From 08746a98cb4867e704bb799506301ca7200d78fa Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.org>
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Date: Thu, 20 Aug 2015 13:50:18 +0100
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Subject: [PATCH 163/222] bcm2708-dmaengine: Use more DMA channels (but not 12)
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1) Only the bcm2708_fb drivers uses the legacy DMA API, and
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it requires a BULK-capable channel, so all other types
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(FAST, NORMAL and LITE) can be made available to the regular
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DMA API.
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2) DMA channels 11-14 share an interrupt. The driver can't
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handle this, so don't use channels 12-14 (12 was used, probably
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because it appears to have an interrupt, but in reality that
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interrupt is for activity on ANY channel). This may explain
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a lockup encountered when running out of DMA channels.
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The combined effect of this patch is to leave 7 DMA channels
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available + channel 0 for bcm2708_fb via the legacy API.
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See: https://github.com/raspberrypi/linux/issues/1110
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https://github.com/raspberrypi/linux/issues/1108
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---
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arch/arm/boot/dts/bcm2708_common.dtsi | 5 ++--
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drivers/dma/bcm2708-dmaengine.c | 43 +++++++++++++++++++++++------------
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2 files changed, 31 insertions(+), 17 deletions(-)
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--- a/arch/arm/boot/dts/bcm2708_common.dtsi
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+++ b/arch/arm/boot/dts/bcm2708_common.dtsi
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@@ -59,11 +59,10 @@
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<1 24>,
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<1 25>,
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<1 26>,
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- <1 27>,
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- <1 28>;
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+ <1 27>;
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#dma-cells = <1>;
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- brcm,dma-channel-mask = <0x7f35>;
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+ brcm,dma-channel-mask = <0x0f35>;
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};
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intc: interrupt-controller {
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--- a/drivers/dma/bcm2708-dmaengine.c
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+++ b/drivers/dma/bcm2708-dmaengine.c
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@@ -184,7 +184,7 @@ static void vc_dmaman_init(struct vc_dma
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}
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static int vc_dmaman_chan_alloc(struct vc_dmaman *dmaman,
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- unsigned preferred_feature_set)
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+ unsigned required_feature_set)
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{
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u32 chans;
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int chan = 0;
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@@ -193,10 +193,8 @@ static int vc_dmaman_chan_alloc(struct v
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chans = dmaman->chan_available;
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for (feature = 0; feature < BCM_DMA_FEATURE_COUNT; feature++)
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/* select the subset of available channels with the desired
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- feature so long as some of the candidate channels have that
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- feature */
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- if ((preferred_feature_set & (1 << feature)) &&
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- (chans & dmaman->has_feature[feature]))
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+ features */
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+ if (required_feature_set & (1 << feature))
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chans &= dmaman->has_feature[feature];
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if (!chans)
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@@ -228,7 +226,7 @@ static int vc_dmaman_chan_free(struct vc
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/* DMA Manager Monitor */
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-extern int bcm_dma_chan_alloc(unsigned preferred_feature_set,
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+extern int bcm_dma_chan_alloc(unsigned required_feature_set,
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void __iomem **out_dma_base, int *out_dma_irq)
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{
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struct vc_dmaman *dmaman = g_dmaman;
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@@ -240,7 +238,7 @@ extern int bcm_dma_chan_alloc(unsigned p
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return -ENODEV;
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mutex_lock(&dmaman->lock);
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- chan = vc_dmaman_chan_alloc(dmaman, preferred_feature_set);
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+ chan = vc_dmaman_chan_alloc(dmaman, required_feature_set);
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if (chan < 0)
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goto out;
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@@ -442,6 +440,7 @@ static inline struct bcm2835_desc *to_bc
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return container_of(t, struct bcm2835_desc, vd.tx);
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}
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+#if 0
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static void dma_dumpregs(struct bcm2835_chan *c)
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{
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pr_debug("-------------DMA DUMPREGS-------------\n");
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@@ -457,6 +456,7 @@ static void dma_dumpregs(struct bcm2835_
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readl(c->chan_base + BCM2835_DMA_NEXTCB));
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pr_debug("--------------------------------------\n");
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}
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+#endif
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static void bcm2835_dma_desc_free(struct virt_dma_desc *vd)
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{
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@@ -862,6 +862,7 @@ static struct dma_async_tx_descriptor *b
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uint32_t len = sg_dma_len(sgent);
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for (j = 0; j < len; j += max_size) {
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+ u32 waits;
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struct bcm2835_dma_cb *control_block =
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&d->control_block_base[i+splitct];
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@@ -879,7 +880,7 @@ static struct dma_async_tx_descriptor *b
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}
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/* Common part */
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- u32 waits = SDHCI_BCM_DMA_WAITS;
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+ waits = SDHCI_BCM_DMA_WAITS;
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if ((dma_debug >> 0) & 0x1f)
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waits = (dma_debug >> 0) & 0x1f;
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control_block->info |= BCM2835_DMA_WAITS(waits);
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@@ -1074,6 +1075,14 @@ static int bcm2835_dma_probe(struct plat
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int rc;
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int i;
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int irq;
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+#ifdef CONFIG_DMA_BCM2708_LEGACY
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+ static const u32 wanted_features[] = {
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+ BCM_DMA_FEATURE_FAST,
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+ BCM_DMA_FEATURE_NORMAL,
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+ BCM_DMA_FEATURE_LITE
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+ };
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+ int j;
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+#endif
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if (!pdev->dev.dma_mask)
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@@ -1120,20 +1129,24 @@ static int bcm2835_dma_probe(struct plat
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platform_set_drvdata(pdev, od);
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- for (i = 0; i < 5; i++) {
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+ for (i = 0, j = 0; j < ARRAY_SIZE(wanted_features);) {
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+
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void __iomem *chan_base;
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int chan_id;
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- chan_id = bcm_dma_chan_alloc(BCM_DMA_FEATURE_LITE,
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- &chan_base,
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- &irq);
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-
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- if (chan_id < 0)
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- break;
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+ chan_id = bcm_dma_chan_alloc(wanted_features[j],
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+ &chan_base,
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+ &irq);
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+
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+ if (chan_id < 0) {
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+ j++;
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+ continue;
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+ }
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rc = bcm2708_dma_chan_init(od, chan_base, chan_id, irq);
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if (rc)
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goto err_no_dma;
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+ i++;
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}
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if (pdev->dev.of_node) {
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@@ -1146,6 +1159,8 @@ static int bcm2835_dma_probe(struct plat
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}
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}
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+ dev_info(&pdev->dev, "Initialized %i DMA channels (+ 1 legacy)\n", i);
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+
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#else
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rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
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if (rc)
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