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  1. 10 9月, 2010 24 次提交
  3. 09 9月, 2010 13 次提交
  5. 08 9月, 2010 3 次提交
    • R
      ARM: Ensure PTE modifications via dma_alloc_coherent are visible · 2be23c47
      由 Russell King 提交于 
      Dave Hylands reports:
| We've observed a problem with dma_alloc_writecombine when the system
| is under heavy load (heavy bus traffic).  We've managed to reduce the
| problem to the following snippet, which is run from a kthread in a
| continuous loop:
|
|   void *virtAddr;
|   dma_addr_t physAddr;
|   unsigned int numBytes = 256;
|
|   for (;;) {
|       virtAddr = dma_alloc_writecombine(NULL,
|             numBytes, &physAddr, GFP_KERNEL);
|       if (virtAddr == NULL) {
|          printk(KERN_ERR "Running out of memory\n");
|          break;
|       }
|
|       /* access DMA memory allocated */
|       tmp = virtAddr;
|       *tmp = 0x77;
|
|       /* free DMA memory */
|       dma_free_writecombine(NULL,
|             numBytes, virtAddr, physAddr);
|
|         ...sleep here...
|     }
|
| By itself, the code will run forever with no issues. However, as we
| increase our bus traffic (typically using DMA) then the *tmp = 0x77
| line will eventually cause a page fault. If we add a small delay (a
| few microseconds) before the *tmp = 0x77, then we don't see a page
| fault, even under heavy load.

A dsb() is required after modifying the PTE entries to ensure that they
will always be visible.  Add this dsb().
Reported-by: NDave Hylands <dhylands@gmail.com>
Tested-by: NDave Hylands <dhylands@gmail.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
      2be23c47
    • T
      semaphore: Add DEFINE_SEMAPHORE · febc88c5
      由 Thomas Gleixner 提交于 
      The full cleanup of init_MUTEX[_LOCKED] and DECLARE_MUTEX has not been
done. Some of the users are real semaphores and we should name them as
such instead of confusing everyone with "MUTEX".

Provide the infrastructure to get finally rid of init_MUTEX[_LOCKED]
and DECLARE_MUTEX.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>
LKML-Reference: <20100907125054.795929962@linutronix.de>
      febc88c5
    • M
      ARM: 6359/1: ep93xx: move clock initialization earlier · a387f0f5
      由 Mika Westerberg 提交于 
      Commit 7cfe2494 ("ARM: AMBA: Add pclk support to AMBA bus
infrastructure") changed AMBA bus to handle the PCLK automatically.
However, in EP93xx clock initialization is arch_initcall which is done
later than AMBA device identification. This causes
amba_get_enable_pclk() to fail resulting device where UARTs are not
functional.

So change ep93xx_clock_init() to be postcore_initcall.
Signed-off-by: NMika Westerberg <mika.westerberg@iki.fi>
Acked-by: NH Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
      a387f0f5