Hi,
I messed up the register names in the commit log. Will fix in v2.
On 05/22/2014 05:30 PM, Daniel Mack wrote:
> When a 0-length packet is received on the bus, desc->pd6 contains 1, and
... 'desc->pd0' ...
> the current residue calculation reports back that 1 byte has been
> transferred. This is not according to what the datasheet says, but it's
> been the case on an AM335x board, very reproducible.
>
> Fix this by looking at bit 19 in PD2 of the completed packet. This bit
> will tell us if a zero-length packet was received on a queue. If it's
> set, ignore pd2 and report a total length of 0.
... 'ignore pd0' ...
>
> Signed-off-by: Daniel Mack <zonque@xxxxxxxxx>
> ---
> drivers/dma/cppi41.c | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/dma/cppi41.c b/drivers/dma/cppi41.c
> index d028f36..8f8b0b6 100644
> --- a/drivers/dma/cppi41.c
> +++ b/drivers/dma/cppi41.c
> @@ -86,6 +86,9 @@
>
> #define USBSS_IRQ_PD_COMP (1 << 2)
>
> +/* Packet Descriptor */
> +#define PD2_ZERO_LENGTH (1 << 19)
> +
> struct cppi41_channel {
> struct dma_chan chan;
> struct dma_async_tx_descriptor txd;
> @@ -307,7 +310,7 @@ static irqreturn_t cppi41_irq(int irq, void *data)
> __iormb();
>
> while (val) {
> - u32 desc;
> + u32 desc, len;
>
> q_num = __fls(val);
> val &= ~(1 << q_num);
> @@ -319,9 +322,13 @@ static irqreturn_t cppi41_irq(int irq, void *data)
> q_num, desc);
> continue;
> }
> - c->residue = pd_trans_len(c->desc->pd6) -
> - pd_trans_len(c->desc->pd0);
>
> + if (c->desc->pd2 & PD2_ZERO_LENGTH)
> + len = 0;
> + else
> + len = pd_trans_len(c->desc->pd0);
> +
> + c->residue = pd_trans_len(c->desc->pd6) - len;
> dma_cookie_complete(&c->txd);
> c->txd.callback(c->txd.callback_param);
> }
>
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