target/linux/brcm2708/patches-4.1/0163-bcm2708-dmaengine-Use-more-DMA-channels-but-not-12.patch

   1 From 08746a98cb4867e704bb799506301ca7200d78fa Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.org>
   3 Date: Thu, 20 Aug 2015 13:50:18 +0100
   4 Subject: [PATCH 163/222] bcm2708-dmaengine: Use more DMA channels (but not 12)
   5
   6 1) Only the bcm2708_fb drivers uses the legacy DMA API, and
   7 it requires a BULK-capable channel, so all other types
   8 (FAST, NORMAL and LITE) can be made available to the regular
   9 DMA API.
  10
  11 2) DMA channels 11-14 share an interrupt. The driver can't
  12 handle this, so don't use channels 12-14 (12 was used, probably
  13 because it appears to have an interrupt, but in reality that
  14 interrupt is for activity on ANY channel). This may explain
  15 a lockup encountered when running out of DMA channels.
  16
  17 The combined effect of this patch is to leave 7 DMA channels
  18 available + channel 0 for bcm2708_fb via the legacy API.
  19
  20 See: https://github.com/raspberrypi/linux/issues/1110
  21      https://github.com/raspberrypi/linux/issues/1108
  22 ---
  23  arch/arm/boot/dts/bcm2708_common.dtsi |  5 ++--
  24  drivers/dma/bcm2708-dmaengine.c       | 43 +++++++++++++++++++++++------------
  25  2 files changed, 31 insertions(+), 17 deletions(-)
  26
  27 --- a/arch/arm/boot/dts/bcm2708_common.dtsi
  28 +++ b/arch/arm/boot/dts/bcm2708_common.dtsi
  29 @@ -59,11 +59,10 @@
  30                                      <1 24>,
  31                                      <1 25>,
  32                                      <1 26>,
  33 -                                    <1 27>,
  34 -                                    <1 28>;
  35 +                                    <1 27>;
  36
  37                         #dma-cells = <1>;
  38 -                       brcm,dma-channel-mask = <0x7f35>;
  39 +                       brcm,dma-channel-mask = <0x0f35>;
  40                 };
  41
  42                 intc: interrupt-controller {
  43 --- a/drivers/dma/bcm2708-dmaengine.c
  44 +++ b/drivers/dma/bcm2708-dmaengine.c
  45 @@ -184,7 +184,7 @@ static void vc_dmaman_init(struct vc_dma
  46  }
  47
  48  static int vc_dmaman_chan_alloc(struct vc_dmaman *dmaman,
  49 -                               unsigned preferred_feature_set)
  50 +                               unsigned required_feature_set)
  51  {
  52         u32 chans;
  53         int chan = 0;
  54 @@ -193,10 +193,8 @@ static int vc_dmaman_chan_alloc(struct v
  55         chans = dmaman->chan_available;
  56         for (feature = 0; feature < BCM_DMA_FEATURE_COUNT; feature++)
  57                 /* select the subset of available channels with the desired
  58 -                  feature so long as some of the candidate channels have that
  59 -                  feature */
  60 -               if ((preferred_feature_set & (1 << feature)) &&
  61 -                   (chans & dmaman->has_feature[feature]))
  62 +                  features */
  63 +               if (required_feature_set & (1 << feature))
  64                         chans &= dmaman->has_feature[feature];
  65
  66         if (!chans)
  67 @@ -228,7 +226,7 @@ static int vc_dmaman_chan_free(struct vc
  68
  69  /* DMA Manager Monitor */
  70
  71 -extern int bcm_dma_chan_alloc(unsigned preferred_feature_set,
  72 +extern int bcm_dma_chan_alloc(unsigned required_feature_set,
  73                               void __iomem **out_dma_base, int *out_dma_irq)
  74  {
  75         struct vc_dmaman *dmaman = g_dmaman;
  76 @@ -240,7 +238,7 @@ extern int bcm_dma_chan_alloc(unsigned p
  77                 return -ENODEV;
  78
  79         mutex_lock(&dmaman->lock);
  80 -       chan = vc_dmaman_chan_alloc(dmaman, preferred_feature_set);
  81 +       chan = vc_dmaman_chan_alloc(dmaman, required_feature_set);
  82         if (chan < 0)
  83                 goto out;
  84
  85 @@ -442,6 +440,7 @@ static inline struct bcm2835_desc *to_bc
  86         return container_of(t, struct bcm2835_desc, vd.tx);
  87  }
  88
  89 +#if 0
  90  static void dma_dumpregs(struct bcm2835_chan *c)
  91  {
  92         pr_debug("-------------DMA DUMPREGS-------------\n");
  93 @@ -457,6 +456,7 @@ static void dma_dumpregs(struct bcm2835_
  94                 readl(c->chan_base + BCM2835_DMA_NEXTCB));
  95         pr_debug("--------------------------------------\n");
  96  }
  97 +#endif
  98
  99  static void bcm2835_dma_desc_free(struct virt_dma_desc *vd)
 100  {
 101 @@ -862,6 +862,7 @@ static struct dma_async_tx_descriptor *b
 102                 uint32_t len = sg_dma_len(sgent);
 103
 104                 for (j = 0; j < len; j += max_size) {
 105 +                       u32 waits;
 106                         struct bcm2835_dma_cb *control_block =
 107                                 &d->control_block_base[i+splitct];
 108
 109 @@ -879,7 +880,7 @@ static struct dma_async_tx_descriptor *b
 110                         }
 111
 112                         /* Common part */
 113 -                       u32 waits = SDHCI_BCM_DMA_WAITS;
 114 +                       waits = SDHCI_BCM_DMA_WAITS;
 115                         if ((dma_debug >> 0) & 0x1f)
 116                                 waits = (dma_debug >> 0) & 0x1f;
 117                         control_block->info |= BCM2835_DMA_WAITS(waits);
 118 @@ -1074,6 +1075,14 @@ static int bcm2835_dma_probe(struct plat
 119         int rc;
 120         int i;
 121         int irq;
 122 +#ifdef CONFIG_DMA_BCM2708_LEGACY
 123 +       static const u32 wanted_features[] = {
 124 +               BCM_DMA_FEATURE_FAST,
 125 +               BCM_DMA_FEATURE_NORMAL,
 126 +               BCM_DMA_FEATURE_LITE
 127 +       };
 128 +       int j;
 129 +#endif
 130
 131
 132         if (!pdev->dev.dma_mask)
 133 @@ -1120,20 +1129,24 @@ static int bcm2835_dma_probe(struct plat
 134
 135         platform_set_drvdata(pdev, od);
 136
 137 -       for (i = 0; i < 5; i++) {
 138 +       for (i = 0, j = 0; j < ARRAY_SIZE(wanted_features);) {
 139 +
 140                 void __iomem *chan_base;
 141                 int chan_id;
 142
 143 -               chan_id = bcm_dma_chan_alloc(BCM_DMA_FEATURE_LITE,
 144 -                       &chan_base,
 145 -                       &irq);
 146 -
 147 -               if (chan_id < 0)
 148 -                       break;
 149 +               chan_id = bcm_dma_chan_alloc(wanted_features[j],
 150 +                                            &chan_base,
 151 +                                            &irq);
 152 +
 153 +               if (chan_id < 0) {
 154 +                       j++;
 155 +                       continue;
 156 +               }
 157
 158                 rc = bcm2708_dma_chan_init(od, chan_base, chan_id, irq);
 159                 if (rc)
 160                         goto err_no_dma;
 161 +               i++;
 162         }
 163
 164         if (pdev->dev.of_node) {
 165 @@ -1146,6 +1159,8 @@ static int bcm2835_dma_probe(struct plat
 166                 }
 167         }
 168
 169 +       dev_info(&pdev->dev, "Initialized %i DMA channels (+ 1 legacy)\n", i);
 170 +
 171  #else
 172         rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
 173         if (rc)