From 4e62a443aa8ffecca7918db93329d8bd8210a92c Mon Sep 17 00:00:00 2001 From: Phil Elwell 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)