sync vapier-m

[patches.git] / spi-flash-dma.patch

diff --git a/spi-flash-dma.patch b/spi-flash-dma.patch
new file mode 100644 (file)
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 */