Messages in this thread | | | Date | Fri, 07 Oct 2016 11:06:25 -0700 | From | Stefan Agner <> | Subject | Re: [PATCH] tty: serial: fsl_lpuart: Fix Tx DMA edge case |
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On 2016-10-06 15:13, Aaron Brice wrote: > In the case where head == 0 on the circular buffer, there should be one > DMA buffer, not two. The second zero-length buffer would break the > lpuart driver, transfer would never complete.
That looks right, and seems to work fine here:
Acked-by: Stefan Agner <stefan@agner.ch> Tested-by: Stefan Agner <stefan@agner.ch>
@Greg, would be good if this would still make it into 4.9.
-- Stefan
> > Signed-off-by: Aaron Brice <aaron.brice@datasoft.com> > --- > drivers/tty/serial/fsl_lpuart.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c > index de9d510..76103f2 100644 > --- a/drivers/tty/serial/fsl_lpuart.c > +++ b/drivers/tty/serial/fsl_lpuart.c > @@ -328,7 +328,7 @@ static void lpuart_dma_tx(struct lpuart_port *sport) > > sport->dma_tx_bytes = uart_circ_chars_pending(xmit); > > - if (xmit->tail < xmit->head) { > + if (xmit->tail < xmit->head || xmit->head == 0) { > sport->dma_tx_nents = 1; > sg_init_one(sgl, xmit->buf + xmit->tail, sport->dma_tx_bytes); > } else { > @@ -359,7 +359,6 @@ static void lpuart_dma_tx(struct lpuart_port *sport) > sport->dma_tx_in_progress = true; > sport->dma_tx_cookie = dmaengine_submit(sport->dma_tx_desc); > dma_async_issue_pending(sport->dma_tx_chan); > - > } > > static void lpuart_dma_tx_complete(void *arg)
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