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authorStephen Warren <swarren@nvidia.com>2011-02-23 14:49:30 -0700
committerColin Cross <ccross@android.com>2011-02-23 14:06:03 -0800
commitccac05152e7c6a8103b9e7a801bc995180a800fc (patch)
tree034bc068b7cd9c3042c52f3cf8dc77ccf701c098 /arch/arm/mach-tegra/dma.c
parentddb7d5d80edb58e8235f1bc6c350eac40bfe85d1 (diff)
ARM: Tegra: DMA: Fail safe if initialization fails
tegra_dma_init currently simply bails out early if any initialization fails. This skips various data-structure initialization. In turn, this means that tegra_dma_allocate_channel can still hand out channels. In this case, when tegra_dma_free_channel is called, which calls tegra_dma_cancel, the walking on ch->list will OOPS since the list's next/prev pointers may still be NULL. To solve this, add an explicit "initialized" flag, only set this once _init has fully completed successfully, and have _allocate_channel refuse to hand out channels if this is not set. While at it, simplify _init: * Remove redundant memsets * Use bitmap_fill to mark all channels as in-use up-front, and remove some now-redundant bitmap initialization loops. * Only mark a channel as free once all channel-related initialization has completed. Finally, the successful exit path from _init always has ret==0, so just hard-code that return. The error path still returns ret. Signed-off-by: Stephen Warren <swarren@nvidia.com> Signed-off-by: Colin Cross <ccross@android.com>
Diffstat (limited to 'arch/arm/mach-tegra/dma.c')
-rw-r--r--arch/arm/mach-tegra/dma.c22
1 files changed, 10 insertions, 12 deletions
diff --git a/arch/arm/mach-tegra/dma.c b/arch/arm/mach-tegra/dma.c
index bd4f62a613a..e945ae28ee7 100644
--- a/arch/arm/mach-tegra/dma.c
+++ b/arch/arm/mach-tegra/dma.c
@@ -127,6 +127,7 @@ struct tegra_dma_channel {
#define NV_DMA_MAX_CHANNELS 32
+static bool tegra_dma_initialized;
static DEFINE_MUTEX(tegra_dma_lock);
static DECLARE_BITMAP(channel_usage, NV_DMA_MAX_CHANNELS);
@@ -352,6 +353,9 @@ struct tegra_dma_channel *tegra_dma_allocate_channel(int mode)
int channel;
struct tegra_dma_channel *ch = NULL;
+ if (WARN_ON(!tegra_dma_initialized))
+ return NULL;
+
mutex_lock(&tegra_dma_lock);
/* first channel is the shared channel */
@@ -678,6 +682,8 @@ int __init tegra_dma_init(void)
void __iomem *addr;
struct clk *c;
+ bitmap_fill(channel_usage, NV_DMA_MAX_CHANNELS);
+
c = clk_get_sys("tegra-dma", NULL);
if (IS_ERR(c)) {
pr_err("Unable to get clock for APB DMA\n");
@@ -696,18 +702,9 @@ int __init tegra_dma_init(void)
writel(0xFFFFFFFFul >> (31 - TEGRA_SYSTEM_DMA_CH_MAX),
addr + APB_DMA_IRQ_MASK_SET);
- memset(channel_usage, 0, sizeof(channel_usage));
- memset(dma_channels, 0, sizeof(dma_channels));
-
- /* Reserve all the channels we are not supposed to touch */
- for (i = 0; i < TEGRA_SYSTEM_DMA_CH_MIN; i++)
- __set_bit(i, channel_usage);
-
for (i = TEGRA_SYSTEM_DMA_CH_MIN; i <= TEGRA_SYSTEM_DMA_CH_MAX; i++) {
struct tegra_dma_channel *ch = &dma_channels[i];
- __clear_bit(i, channel_usage);
-
ch->id = i;
snprintf(ch->name, TEGRA_DMA_NAME_SIZE, "dma_channel_%d", i);
@@ -726,14 +723,15 @@ int __init tegra_dma_init(void)
goto fail;
}
ch->irq = irq;
+
+ __clear_bit(i, channel_usage);
}
/* mark the shared channel allocated */
__set_bit(TEGRA_SYSTEM_DMA_CH_MIN, channel_usage);
- for (i = TEGRA_SYSTEM_DMA_CH_MAX+1; i < NV_DMA_MAX_CHANNELS; i++)
- __set_bit(i, channel_usage);
+ tegra_dma_initialized = true;
- return ret;
+ return 0;
fail:
writel(0, addr + APB_DMA_GEN);
for (i = TEGRA_SYSTEM_DMA_CH_MIN; i <= TEGRA_SYSTEM_DMA_CH_MAX; i++) {