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SubjectRe: [PATCH] pch_dma: Fix CTL register access issue
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On Thu, 2011-07-14 at 09:52 +0900, Tomoya MORINAGA wrote:
> 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>
> ---
> 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
APPLIED, Thanks

--
~Vinod Koul
Intel Corp.



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