PKGBUILDs/core/linux-trimslice/armdma.patch

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
  */