serial: 8250_dma: TX optimisation
Remove one useless wakeup, and do not use DMA with zero byte transfers. Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -67,12 +67,12 @@ int serial8250_tx_dma(struct uart_8250_port *p)
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struct circ_buf *xmit = &p->port.state->xmit;
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struct dma_async_tx_descriptor *desc;
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if (dma->tx_running) {
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uart_write_wakeup(&p->port);
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if (dma->tx_running)
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return -EBUSY;
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}
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dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
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if (!dma->tx_size)
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return -EINVAL;
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desc = dmaengine_prep_slave_single(dma->txchan,
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dma->tx_addr + xmit->tail,
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