diff options
| author | Dan Williams <dan.j.williams@intel.com> | 2009-09-08 17:42:51 -0700 |
|---|---|---|
| committer | Dan Williams <dan.j.williams@intel.com> | 2009-09-08 17:42:51 -0700 |
| commit | 138f4c359d23d2ec38d18bd70dd9613ae515fe93 (patch) | |
| tree | ad7fafba6eac74d9d92ade839a65171466d67a70 /drivers/dma | |
| parent | 0403e3827788d878163f9ef0541b748b0f88ca5d (diff) | |
dmaengine, async_tx: add a "no channel switch" allocator
Channel switching is problematic for some dmaengine drivers as the
architecture precludes separating the ->prep from ->submit. In these
cases the driver can select ASYNC_TX_DISABLE_CHANNEL_SWITCH to modify
the async_tx allocator to only return channels that support all of the
required asynchronous operations.
For example MD_RAID456=y selects support for asynchronous xor, xor
validate, pq, pq validate, and memcpy. When
ASYNC_TX_DISABLE_CHANNEL_SWITCH=y any channel with all these
capabilities is marked DMA_ASYNC_TX allowing async_tx_find_channel() to
quickly locate compatible channels with the guarantee that dependency
chains will remain on one channel. When
ASYNC_TX_DISABLE_CHANNEL_SWITCH=n async_tx_find_channel() may select
channels that lead to operation chains that need to cross channel
boundaries using the async_tx channel switch capability.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/dma')
| -rw-r--r-- | drivers/dma/Kconfig | 4 | ||||
| -rw-r--r-- | drivers/dma/dmaengine.c | 40 |
2 files changed, 44 insertions, 0 deletions
diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig index 912a51b5cbd..ddcd9793b25 100644 --- a/drivers/dma/Kconfig +++ b/drivers/dma/Kconfig @@ -17,11 +17,15 @@ if DMADEVICES comment "DMA Devices" +config ASYNC_TX_DISABLE_CHANNEL_SWITCH + bool + config INTEL_IOATDMA tristate "Intel I/OAT DMA support" depends on PCI && X86 select DMA_ENGINE select DCA + select ASYNC_TX_DISABLE_CHANNEL_SWITCH help Enable support for the Intel(R) I/OAT DMA engine present in recent Intel Xeon chipsets. diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index 96598479eec..d5bc628d207 100644 --- a/drivers/dma/dmaengine.c +++ b/drivers/dma/dmaengine.c @@ -608,6 +608,40 @@ void dmaengine_put(void) } EXPORT_SYMBOL(dmaengine_put); +static bool device_has_all_tx_types(struct dma_device *device) +{ + /* A device that satisfies this test has channels that will never cause + * an async_tx channel switch event as all possible operation types can + * be handled. + */ + #ifdef CONFIG_ASYNC_TX_DMA + if (!dma_has_cap(DMA_INTERRUPT, device->cap_mask)) + return false; + #endif + + #if defined(CONFIG_ASYNC_MEMCPY) || defined(CONFIG_ASYNC_MEMCPY_MODULE) + if (!dma_has_cap(DMA_MEMCPY, device->cap_mask)) + return false; + #endif + + #if defined(CONFIG_ASYNC_MEMSET) || defined(CONFIG_ASYNC_MEMSET_MODULE) + if (!dma_has_cap(DMA_MEMSET, device->cap_mask)) + return false; + #endif + + #if defined(CONFIG_ASYNC_XOR) || defined(CONFIG_ASYNC_XOR_MODULE) + if (!dma_has_cap(DMA_XOR, device->cap_mask)) + return false; + #endif + + #if defined(CONFIG_ASYNC_PQ) || defined(CONFIG_ASYNC_PQ_MODULE) + if (!dma_has_cap(DMA_PQ, device->cap_mask)) + return false; + #endif + + return true; +} + static int get_dma_id(struct dma_device *device) { int rc; @@ -665,6 +699,12 @@ int dma_async_device_register(struct dma_device *device) BUG_ON(!device->device_issue_pending); BUG_ON(!device->dev); + /* note: this only matters in the + * CONFIG_ASYNC_TX_DISABLE_CHANNEL_SWITCH=y case + */ + if (device_has_all_tx_types(device)) + dma_cap_set(DMA_ASYNC_TX, device->cap_mask); + idr_ref = kmalloc(sizeof(*idr_ref), GFP_KERNEL); if (!idr_ref) return -ENOMEM; |