mtd: r852: Few fixes for problems that occur when card is rapidly inserted/removed.

First don't enable card detection logic to early. Second be very careful with
DMA engine, to be sure it doesn't write to kernel memory driver doesn't own.

Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 17 insertions, 4 deletions

diff --git a/drivers/mtd/nand/r852.c b/drivers/mtd/nand/r852.c
index 218a42dadff1..cb271167b4a5 100644
--- a/drivers/mtd/nand/r852.c
+++ b/drivers/mtd/nand/r852.c
@@ -96,14 +96,21 @@ static void r852_dma_enable(struct r852_device *dev)
         if (dev->dma_dir)
                 dma_reg |= R852_DMA_READ;
 
-        if (dev->dma_state == DMA_INTERNAL)
+        if (dev->dma_state == DMA_INTERNAL) {
                 dma_reg |= R852_DMA_INTERNAL;
-        else {
+                /* Precaution to make sure HW doesn't write */
+                        /* to random kernel memory */
+                r852_write_reg_dword(dev, R852_DMA_ADDR,
+                        cpu_to_le32(dev->phys_bounce_buffer));
+        } else {
                 dma_reg |= R852_DMA_MEMORY;
                 r852_write_reg_dword(dev, R852_DMA_ADDR,
                         cpu_to_le32(dev->phys_dma_addr));
         }
 
+        /* Precaution: make sure write reached the device */
+        r852_read_reg_dword(dev, R852_DMA_ADDR);
+
         r852_write_reg_dword(dev, R852_DMA_SETTINGS, dma_reg);
 
         /* Set dma irq */
@@ -129,6 +136,11 @@ static void r852_dma_done(struct r852_device *dev, int error)
         r852_write_reg_dword(dev, R852_DMA_SETTINGS, 0);
         r852_write_reg_dword(dev, R852_DMA_IRQ_ENABLE, 0);
 
+        /* Precaution to make sure HW doesn't write to random kernel memory */
+        r852_write_reg_dword(dev, R852_DMA_ADDR,
+                cpu_to_le32(dev->phys_bounce_buffer));
+        r852_read_reg_dword(dev, R852_DMA_ADDR);
+
         dev->dma_error = error;
         dev->dma_stage = 0;
 
@@ -579,6 +591,7 @@ void r852_card_update_present(struct r852_device *dev)
 void r852_update_card_detect(struct r852_device *dev)
 {
         int card_detect_reg = r852_read_reg(dev, R852_CARD_IRQ_ENABLE);
+        dev->card_unstable = 0;
 
         card_detect_reg &= ~(R852_CARD_IRQ_REMOVE | R852_CARD_IRQ_INSERT);
         card_detect_reg |= R852_CARD_IRQ_GENABLE;
@@ -690,10 +703,10 @@ void r852_card_detect_work(struct work_struct *work)
         struct r852_device *dev =
                 container_of(work, struct r852_device, card_detect_work.work);
 
-        r852_update_card_detect(dev);
+        r852_card_update_present(dev);
         dev->card_unstable = 0;
 
-        /* false alarm */
+        /* False alarm */
         if (dev->card_detected == dev->card_registred)
                 goto exit;