X-Git-Url: https://git.wh0rd.org/?p=patches.git;a=blobdiff_plain;f=spi-flash-dma.patch;fp=spi-flash-dma.patch;h=492f37ab1a8f6215cb52140eed36810eeac29f08;hp=0000000000000000000000000000000000000000;hb=b77ff2bc4309cd456bbee6a5eb08dc2426619f56;hpb=5e993f12c1f493f3b518b651ebb3861e2a67673d

diff --git a/spi-flash-dma.patch b/spi-flash-dma.patch
new file mode 100644
index 0000000..492f37a
--- /dev/null
+++ b/spi-flash-dma.patch
@@ -0,0 +1,57 @@
+--- spi_bfin5xx.c	(revision 5493)
++++ spi_bfin5xx.c	(working copy)
+@@ -619,6 +619,7 @@ static void pump_transfers(unsigned long
+ 	struct spi_transfer *transfer = NULL;
+ 	struct spi_transfer *previous = NULL;
+ 	struct chip_data *chip = NULL;
++	unsigned long flags;
+ 	u8 width;
+ 	u16 cr, dma_width, dma_config;
+ 	u32 tranf_success = 1;
+@@ -766,7 +767,6 @@ static void pump_transfers(unsigned long
+ 
+ 		disable_dma(drv_data->dma_channel);
+ 		clear_dma_irqstat(drv_data->dma_channel);
+-		bfin_spi_disable(drv_data);
+ 
+ 		/* config dma channel */
+ 		dev_dbg(&drv_data->pdev->dev, "doing dma transfer\n");
+@@ -797,8 +797,7 @@ static void pump_transfers(unsigned long
+ 			enable_dma(drv_data->dma_channel);
+ 
+ 			/* start SPI transfer */
+-			write_CTRL(drv_data,
+-				(cr | BIT_CTL_TIMOD_DMA_TX | BIT_CTL_ENABLE));
++			write_CTRL(drv_data, cr | BIT_CTL_TIMOD_DMA_TX);
+ 
+ 			/* just return here, there can only be one transfer
+ 			 * in this mode
+@@ -840,14 +839,22 @@ static void pump_transfers(unsigned long
+ 		} else
+ 			BUG();
+ 
+-		/* start dma */
+-		dma_enable_irq(drv_data->dma_channel);
+-		set_dma_config(drv_data->dma_channel, dma_config);
++		/* oh man, here there be monsters ... and i dont mean the
++		 * fluffy cute ones from pixar, i mean the kind that'll eat
++		 * your data, kick your dog, and love it all.  do *not* try
++		 * and change these lines unless you (1) heavily test DMA
++		 * with SPI flashes on a loaded system (e.g. ping floods),
++		 * (2) know just how broken the DMA engine interaction with
++		 * the SPI peripheral is, and (3) have someone else to blame
++		 * when you screw it all up anyways.
++		 */
+ 		set_dma_start_addr(drv_data->dma_channel, dma_start_addr);
++		set_dma_config(drv_data->dma_channel, dma_config);
++		local_irq_save(flags);
+ 		enable_dma(drv_data->dma_channel);
+-
+-		/* start SPI transfer */
+-		write_CTRL(drv_data, (cr | BIT_CTL_ENABLE));
++		write_CTRL(drv_data, cr);
++		dma_enable_irq(drv_data->dma_channel);
++		local_irq_restore(flags);
+ 
+ 	} else {
+ 		/* IO mode write then read */