PKGBUILDs/core/linux-raspberrypi-latest/armdma.patch

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diff -urN linux-3.1-rc4-a/arch/arm/include/asm/dma-mapping.h linux-3.1-rc4-b/arch/arm/include/asm/dma-mapping.h
--- linux-3.1-rc4-a/arch/arm/include/asm/dma-mapping.h 2011-08-29 05:16:01.000000000 +0100
+++ linux-3.1-rc4-b/arch/arm/include/asm/dma-mapping.h 2011-09-02 12:09:00.000000000 +0100
@@ -205,6 +205,15 @@
int dma_mmap_writecombine(struct device *, struct vm_area_struct *,
void *, dma_addr_t, size_t);
+#ifdef CONFIG_ARM_DMA_MEM_BUFFERABLE
+#define ARCH_HAS_DMA_COHERENT_WRITE_SYNC
+
+static inline void dma_coherent_write_sync(void)
+{
+ dsb();
+ outer_sync();
+}
+#endif
#ifdef CONFIG_DMABOUNCE
/*
diff -urN linux-3.1-rc4-a/Documentation/DMA-API-HOWTO.txt linux-3.1-rc4-b/Documentation/DMA-API-HOWTO.txt
--- linux-3.1-rc4-a/Documentation/DMA-API-HOWTO.txt 2011-08-29 05:16:01.000000000 +0100
+++ linux-3.1-rc4-b/Documentation/DMA-API-HOWTO.txt 2011-09-02 12:01:09.000000000 +0100
@@ -400,6 +400,22 @@
from a pool before you destroy the pool. This function may not
be called in interrupt context.
+Some architectures which supporting DMA coherent memory may still have write
+buffering between the CPU and DMA memory. This buffering may delay CPU writes
+from reaching coherent memory in a timely manner. These delays in turn can
+lead lead to dramatic performance issues in certain cases. An architecture
+may mitigate this problem to a large degree by having a write buffer flush
+implicit in the MMIO functions used to write to device registers. This works
+for the most common cases where a driver needs to write to a register to tell
+a device that something was written to the shared coherent memory. There are
+other cases where the device polls the dma-coherent memory for data written
+by the driver. In such cases, the driver needs to explicity force write buffer
+data to memory by calling:
+
+ dma_coherent_write_sync();
+
+
+
DMA Direction
The interfaces described in subsequent portions of this document
diff -urN linux-3.1-rc4-a/Documentation/DMA-API.txt linux-3.1-rc4-b/Documentation/DMA-API.txt
--- linux-3.1-rc4-a/Documentation/DMA-API.txt 2011-08-29 05:16:01.000000000 +0100
+++ linux-3.1-rc4-b/Documentation/DMA-API.txt 2011-09-02 12:03:06.000000000 +0100
@@ -418,6 +418,18 @@
....
+Part Ie - Write buffering to dma-coherent memory
+------------------------------------------------
+
+Some architectures supporting DMA coherent memory may have write
+buffering between the CPU and DMA memory. This buffering may delay
+CPU writes from reaching coherent memory in a timely manner.
+
+ void
+ dma_coherent_write_sync()
+
+Force any outstanding coherent writes to memory.
+
Part II - Advanced dma_ usage
-----------------------------
diff -urN linux-3.1-rc4-a/drivers/usb/host/ehci-q.c linux-3.1-rc4-b/drivers/usb/host/ehci-q.c
--- linux-3.1-rc4-a/drivers/usb/host/ehci-q.c 2011-08-29 05:16:01.000000000 +0100
+++ linux-3.1-rc4-b/drivers/usb/host/ehci-q.c 2011-09-02 12:17:20.000000000 +0100
@@ -114,6 +114,7 @@
/* HC must see latest qtd and qh data before we clear ACTIVE+HALT */
wmb ();
hw->hw_token &= cpu_to_hc32(ehci, QTD_TOGGLE | QTD_STS_PING);
+ dma_coherent_write_sync();
}
/* if it weren't for a common silicon quirk (writing the dummy into the qh
@@ -404,6 +405,7 @@
wmb();
hw->hw_token = cpu_to_hc32(ehci,
token);
+ dma_coherent_write_sync();
goto retry_xacterr;
}
stopped = 1;
@@ -753,8 +755,10 @@
}
/* by default, enable interrupt on urb completion */
- if (likely (!(urb->transfer_flags & URB_NO_INTERRUPT)))
+ if (likely(!(urb->transfer_flags & URB_NO_INTERRUPT))) {
qtd->hw_token |= cpu_to_hc32(ehci, QTD_IOC);
+ dma_coherent_write_sync();
+ }
return head;
cleanup:
@@ -1081,6 +1085,7 @@
/* let the hc process these next qtds */
wmb ();
dummy->hw_token = token;
+ dma_coherent_write_sync();
urb->hcpriv = qh_get (qh);
}
diff -urN linux-3.1-rc4-a/include/linux/dma-mapping.h linux-3.1-rc4-b/include/linux/dma-mapping.h
--- linux-3.1-rc4-a/include/linux/dma-mapping.h 2011-08-29 05:16:01.000000000 +0100
+++ linux-3.1-rc4-b/include/linux/dma-mapping.h 2011-09-02 12:06:06.000000000 +0100
@@ -154,6 +154,12 @@
}
#endif
+#ifndef ARCH_HAS_DMA_COHERENT_WRITE_SYNC
+static inline void dma_coherent_write_sync(void)
+{
+}
+#endif
+
/*
* Managed DMA API
*/