pch_dma: Fix CTL register access issue
Tomoya MORINAGA [Thu, 14 Jul 2011 00:52:38 +0000 (09:52 +0900)]
Currently, Mode-Control register is accessed by read-modify-write.

According to DMA hardware specifications datasheet, prohibits this method.
Because this register resets to 0 by DMA HW after DMA transfer completes.
Thus, current read-modify-write processing can cause unexpected behavior.

The datasheet says in case of writing Mode-Control register, set the value for only target channel, the others must set '11b'.
e.g. Set DMA0=01b  DMA11=10b
CTL0=33333331h
CTL2=00002333h

NOTE:
CTL0 includes DMA0~7 Mode-Control register.
CTL2 includes DMA8~11 Mode-Control register.

This patch modifies the issue.

Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/pch_dma.c

index d9d95a4..1ac8d4b 100644 (file)
@@ -62,6 +62,9 @@
 
 #define MAX_CHAN_NR                    8
 
+#define DMA_MASK_CTL0_MODE     0x33333333
+#define DMA_MASK_CTL2_MODE     0x00003333
+
 static unsigned int init_nr_desc_per_channel = 64;
 module_param(init_nr_desc_per_channel, uint, 0644);
 MODULE_PARM_DESC(init_nr_desc_per_channel,
@@ -210,10 +213,17 @@ static void pdc_set_dir(struct dma_chan *chan)
        struct pch_dma_chan *pd_chan = to_pd_chan(chan);
        struct pch_dma *pd = to_pd(chan->device);
        u32 val;
+       u32 mask_mode;
+       u32 mask_ctl;
 
        if (chan->chan_id < 8) {
                val = dma_readl(pd, CTL0);
 
+               mask_mode = DMA_CTL0_MODE_MASK_BITS <<
+                                       (DMA_CTL0_BITS_PER_CH * chan->chan_id);
+               mask_ctl = DMA_MASK_CTL0_MODE & ~(DMA_CTL0_MODE_MASK_BITS <<
+                                      (DMA_CTL0_BITS_PER_CH * chan->chan_id));
+               val &= mask_mode;
                if (pd_chan->dir == DMA_TO_DEVICE)
                        val |= 0x1 << (DMA_CTL0_BITS_PER_CH * chan->chan_id +
                                       DMA_CTL0_DIR_SHIFT_BITS);
@@ -221,18 +231,24 @@ static void pdc_set_dir(struct dma_chan *chan)
                        val &= ~(0x1 << (DMA_CTL0_BITS_PER_CH * chan->chan_id +
                                         DMA_CTL0_DIR_SHIFT_BITS));
 
+               val |= mask_ctl;
                dma_writel(pd, CTL0, val);
        } else {
                int ch = chan->chan_id - 8; /* ch8-->0 ch9-->1 ... ch11->3 */
                val = dma_readl(pd, CTL3);
 
+               mask_mode = DMA_CTL0_MODE_MASK_BITS <<
+                                               (DMA_CTL0_BITS_PER_CH * ch);
+               mask_ctl = DMA_MASK_CTL2_MODE & ~(DMA_CTL0_MODE_MASK_BITS <<
+                                                (DMA_CTL0_BITS_PER_CH * ch));
+               val &= mask_mode;
                if (pd_chan->dir == DMA_TO_DEVICE)
                        val |= 0x1 << (DMA_CTL0_BITS_PER_CH * ch +
                                       DMA_CTL0_DIR_SHIFT_BITS);
                else
                        val &= ~(0x1 << (DMA_CTL0_BITS_PER_CH * ch +
                                         DMA_CTL0_DIR_SHIFT_BITS));
-
+               val |= mask_ctl;
                dma_writel(pd, CTL3, val);
        }
 
@@ -244,26 +260,30 @@ static void pdc_set_mode(struct dma_chan *chan, u32 mode)
 {
        struct pch_dma *pd = to_pd(chan->device);
        u32 val;
+       u32 mask_ctl;
+       u32 mask_dir;
 
        if (chan->chan_id < 8) {
+               mask_ctl = DMA_MASK_CTL0_MODE & ~(DMA_CTL0_MODE_MASK_BITS <<
+                          (DMA_CTL0_BITS_PER_CH * chan->chan_id));
+               mask_dir = 1 << (DMA_CTL0_BITS_PER_CH * chan->chan_id +\
+                                DMA_CTL0_DIR_SHIFT_BITS);
                val = dma_readl(pd, CTL0);
-
-               val &= ~(DMA_CTL0_MODE_MASK_BITS <<
-                       (DMA_CTL0_BITS_PER_CH * chan->chan_id));
+               val &= mask_dir;
                val |= mode << (DMA_CTL0_BITS_PER_CH * chan->chan_id);
-
+               val |= mask_ctl;
                dma_writel(pd, CTL0, val);
        } else {
                int ch = chan->chan_id - 8; /* ch8-->0 ch9-->1 ... ch11->3 */
-
+               mask_ctl = DMA_MASK_CTL2_MODE & ~(DMA_CTL0_MODE_MASK_BITS <<
+                                                (DMA_CTL0_BITS_PER_CH * ch));
+               mask_dir = 1 << (DMA_CTL0_BITS_PER_CH * ch +\
+                                DMA_CTL0_DIR_SHIFT_BITS);
                val = dma_readl(pd, CTL3);
-
-               val &= ~(DMA_CTL0_MODE_MASK_BITS <<
-                       (DMA_CTL0_BITS_PER_CH * ch));
+               val &= mask_dir;
                val |= mode << (DMA_CTL0_BITS_PER_CH * ch);
-
+               val |= mask_ctl;
                dma_writel(pd, CTL3, val);
-
        }
 
        dev_dbg(chan2dev(chan), "pdc_set_mode: chan %d -> %x\n",