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Date: Thu, 14 Jul 2011 09:52:38 +0900
From: Tomoya MORINAGA <tomoya-linux@....okisemi.com>
To: Dan Williams <dan.j.williams@...el.com>,
Vinod Koul <vinod.koul@...el.com>, linux-kernel@...r.kernel.org
Cc: qi.wang@...el.com, yong.y.wang@...el.com, joel.clark@...el.com,
kok.howg.ewe@...el.com, toshiharu-linux@....okisemi.com,
Tomoya MORINAGA <tomoya-linux@....okisemi.com>
Subject: [PATCH] pch_dma: Fix CTL register access issue
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@....okisemi.com>
---
drivers/dma/pch_dma.c | 42 +++++++++++++++++++++++++++++++-----------
1 files changed, 31 insertions(+), 11 deletions(-)
diff --git a/drivers/dma/pch_dma.c b/drivers/dma/pch_dma.c
index 9dc92de..7460490 100644
--- a/drivers/dma/pch_dma.c
+++ b/drivers/dma/pch_dma.c
@@ -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",
--
1.7.4.4
--
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