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From 4e62a443aa8ffecca7918db93329d8bd8210a92c Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Thu, 20 Aug 2015 13:50:18 +0100
Subject: [PATCH 165/171] bcm2708-dmaengine: Use more DMA channels (but not 12)
1) Only the bcm2708_fb drivers uses the legacy DMA API, and
it requires a BULK-capable channel, so all other types
(FAST, NORMAL and LITE) can be made available to the regular
DMA API.
2) DMA channels 11-14 share an interrupt. The driver can't
handle this, so don't use channels 12-14 (12 was used, probably
because it appears to have an interrupt, but in reality that
interrupt is for activity on ANY channel). This may explain
a lockup encountered when running out of DMA channels.
The combined effect of this patch is to leave 7 DMA channels
available + channel 0 for bcm2708_fb via the legacy API.
See: https://github.com/raspberrypi/linux/issues/1110
https://github.com/raspberrypi/linux/issues/1108
---
arch/arm/boot/dts/bcm2708_common.dtsi | 5 ++--
drivers/dma/bcm2708-dmaengine.c | 43 +++++++++++++++++++++++------------
2 files changed, 31 insertions(+), 17 deletions(-)
--- a/arch/arm/boot/dts/bcm2708_common.dtsi
+++ b/arch/arm/boot/dts/bcm2708_common.dtsi
@@ -59,11 +59,10 @@
<1 24>,
<1 25>,
<1 26>,
- <1 27>,
- <1 28>;
+ <1 27>;
#dma-cells = <1>;
- brcm,dma-channel-mask = <0x7f35>;
+ brcm,dma-channel-mask = <0x0f35>;
};
intc: interrupt-controller {
--- a/drivers/dma/bcm2708-dmaengine.c
+++ b/drivers/dma/bcm2708-dmaengine.c
@@ -184,7 +184,7 @@ static void vc_dmaman_init(struct vc_dma
}
static int vc_dmaman_chan_alloc(struct vc_dmaman *dmaman,
- unsigned preferred_feature_set)
+ unsigned required_feature_set)
{
u32 chans;
int chan = 0;
@@ -193,10 +193,8 @@ static int vc_dmaman_chan_alloc(struct v
chans = dmaman->chan_available;
for (feature = 0; feature < BCM_DMA_FEATURE_COUNT; feature++)
/* select the subset of available channels with the desired
- feature so long as some of the candidate channels have that
- feature */
- if ((preferred_feature_set & (1 << feature)) &&
- (chans & dmaman->has_feature[feature]))
+ features */
+ if (required_feature_set & (1 << feature))
chans &= dmaman->has_feature[feature];
if (!chans)
@@ -228,7 +226,7 @@ static int vc_dmaman_chan_free(struct vc
/* DMA Manager Monitor */
-extern int bcm_dma_chan_alloc(unsigned preferred_feature_set,
+extern int bcm_dma_chan_alloc(unsigned required_feature_set,
void __iomem **out_dma_base, int *out_dma_irq)
{
struct vc_dmaman *dmaman = g_dmaman;
@@ -240,7 +238,7 @@ extern int bcm_dma_chan_alloc(unsigned p
return -ENODEV;
mutex_lock(&dmaman->lock);
- chan = vc_dmaman_chan_alloc(dmaman, preferred_feature_set);
+ chan = vc_dmaman_chan_alloc(dmaman, required_feature_set);
if (chan < 0)
goto out;
@@ -442,6 +440,7 @@ static inline struct bcm2835_desc *to_bc
return container_of(t, struct bcm2835_desc, vd.tx);
}
+#if 0
static void dma_dumpregs(struct bcm2835_chan *c)
{
pr_debug("-------------DMA DUMPREGS-------------\n");
@@ -457,6 +456,7 @@ static void dma_dumpregs(struct bcm2835_
readl(c->chan_base + BCM2835_DMA_NEXTCB));
pr_debug("--------------------------------------\n");
}
+#endif
static void bcm2835_dma_desc_free(struct virt_dma_desc *vd)
{
@@ -862,6 +862,7 @@ static struct dma_async_tx_descriptor *b
uint32_t len = sg_dma_len(sgent);
for (j = 0; j < len; j += max_size) {
+ u32 waits;
struct bcm2835_dma_cb *control_block =
&d->control_block_base[i+splitct];
@@ -879,7 +880,7 @@ static struct dma_async_tx_descriptor *b
}
/* Common part */
- u32 waits = SDHCI_BCM_DMA_WAITS;
+ waits = SDHCI_BCM_DMA_WAITS;
if ((dma_debug >> 0) & 0x1f)
waits = (dma_debug >> 0) & 0x1f;
control_block->info |= BCM2835_DMA_WAITS(waits);
@@ -1074,6 +1075,14 @@ static int bcm2835_dma_probe(struct plat
int rc;
int i;
int irq;
+#ifdef CONFIG_DMA_BCM2708_LEGACY
+ static const u32 wanted_features[] = {
+ BCM_DMA_FEATURE_FAST,
+ BCM_DMA_FEATURE_NORMAL,
+ BCM_DMA_FEATURE_LITE
+ };
+ int j;
+#endif
if (!pdev->dev.dma_mask)
@@ -1120,20 +1129,24 @@ static int bcm2835_dma_probe(struct plat
platform_set_drvdata(pdev, od);
- for (i = 0; i < 5; i++) {
+ for (i = 0, j = 0; j < ARRAY_SIZE(wanted_features);) {
+
void __iomem *chan_base;
int chan_id;
- chan_id = bcm_dma_chan_alloc(BCM_DMA_FEATURE_LITE,
- &chan_base,
- &irq);
-
- if (chan_id < 0)
- break;
+ chan_id = bcm_dma_chan_alloc(wanted_features[j],
+ &chan_base,
+ &irq);
+
+ if (chan_id < 0) {
+ j++;
+ continue;
+ }
rc = bcm2708_dma_chan_init(od, chan_base, chan_id, irq);
if (rc)
goto err_no_dma;
+ i++;
}
if (pdev->dev.of_node) {
@@ -1146,6 +1159,8 @@ static int bcm2835_dma_probe(struct plat
}
}
+ dev_info(&pdev->dev, "Initialized %i DMA channels (+ 1 legacy)\n", i);
+
#else
rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
if (rc)
|
