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>

diff --git a/drivers/mtd/nand/r852.c b/drivers/mtd/nand/r852.c
index 218a42dadff1d1f2e699bf0c6ed048189486b937..cb271167b4a51527586fddd07737c61fcd0c6197 100644 (file)
--- 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;