Hi Geert,
One bikeshedding below.
On Mon, Jun 24, 2019 at 02:35:39PM +0200, Geert Uytterhoeven wrote:
[..]
> diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
> index abc705716aa094fd..d4504daff99263f5 100644
> --- a/drivers/tty/serial/sh-sci.c
> +++ b/drivers/tty/serial/sh-sci.c
> @@ -1398,6 +1398,7 @@ static void sci_dma_tx_work_fn(struct work_struct *work)
> struct circ_buf *xmit = &port->state->xmit;
> unsigned long flags;
> dma_addr_t buf;
> + int head, tail;
>
> /*
> * DMA is idle now.
> @@ -1407,16 +1408,23 @@ static void sci_dma_tx_work_fn(struct work_struct *work)
> * consistent xmit buffer state.
> */
> spin_lock_irq(&port->lock);
> - buf = s->tx_dma_addr + (xmit->tail & (UART_XMIT_SIZE - 1));
> + head = xmit->head;
> + tail = xmit->tail;
> + buf = s->tx_dma_addr + (tail & (UART_XMIT_SIZE - 1));
> s->tx_dma_len = min_t(unsigned int,
> - CIRC_CNT(xmit->head, xmit->tail, UART_XMIT_SIZE),
> - CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE));
> - spin_unlock_irq(&port->lock);
> + CIRC_CNT(head, tail, UART_XMIT_SIZE),
> + CIRC_CNT_TO_END(head, tail, UART_XMIT_SIZE));
> + if (!s->tx_dma_len) {
> + /* Transmit buffer has been flushed */
> + spin_unlock_irq(&port->lock);
> + return;
Since we can now return before using the result stored in 'buf', we
could relocate the 'buf' calculation next to the return statement, just
before calling dmaengine_prep_slave_single(), as micro-optimization.
> + }
>
> desc = dmaengine_prep_slave_single(chan, buf, s->tx_dma_len,
> DMA_MEM_TO_DEV,
> DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
Otherwise:
Reviewed-by: Eugeniu Rosca <erosca@xxxxxxxxxxxxxx>
Tested-by: Eugeniu Rosca <erosca@xxxxxxxxxxxxxx>
--
Best Regards,
Eugeniu.
