On Tue, 2019-01-22 at 11:20 -0600, Thor Thayer wrote:
> On 1/21/19 2:29 AM, Atsushi Nemoto wrote:
> > From: Tomonori Sakita <tomonori.sak...@sord.co.jp>
> >
> > If fill_level was not zero and status was not BUSY,
> > result of "tx_prod - tx_cons - inuse" might be zero.
> > Subtracting 1 unconditionally results invalid negative return value
> > on this case.
> > The subtraction is not needed if fill_level was not zero.
> >
> > Signed-off-by: Tomonori Sakita <tomonori.sak...@sord.co.jp>
> > Signed-off-by: Atsushi Nemoto <atsushi.nem...@sord.co.jp>
> > ---
> > drivers/net/ethernet/altera/altera_msgdma.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/altera/altera_msgdma.c
> > b/drivers/net/ethernet/altera/altera_msgdma.c
> > index 0fb986b..3df73d3 100644
> > --- a/drivers/net/ethernet/altera/altera_msgdma.c
> > +++ b/drivers/net/ethernet/altera/altera_msgdma.c
> > @@ -145,7 +145,7 @@ u32 msgdma_tx_completions(struct altera_tse_private
> > *priv)
> > & 0xffff;
> >
> > if (inuse) { /* Tx FIFO is not empty */
> > - ready = priv->tx_prod - priv->tx_cons - inuse - 1;
> > + ready = priv->tx_prod - priv->tx_cons - inuse;
dont think my last email went through..
I am not sure about this. This register indicates the number of entries
still to be processed by the dma. the -1 is intended to represent the
decriptor currently being processed. If ready is
priv->tx_prod - priv->tx_cons - inuse couldn't you end up processing 1
too many packets? IE: ready is 1 greater then the actual completed
packets?
I do agree that we should not be returning a negative value, but i dont
think i agree removing the -1 is the answer. perhaps just check that ready
is greater than 0?
--dalon
> > } else {
> > /* Check for buffered last packet */
> > status = csrrd32(priv->tx_dma_csr, msgdma_csroffs(status));
> >
>
> I'm adding Dalon who has done a lot of work on msgdma. I'd like to get
> his comments.
>
> Thanks,
>
> Thor
>
