From 6dc01aa65306fe46b7ba38db51fad4ed81c23d00 Mon Sep 17 00:00:00 2001 From: Chanho Min Date: Mon, 20 Feb 2012 10:24:40 +0900 Subject: =?UTF-8?q?amba-pl011=E2=80=8B/dma:=20Add=20check=20for=20the=20re?= =?UTF-8?q?sidue=20in=20DMA=20callback?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In DMA-operated uart, I found that rx data can be taken by the UART interrupts during the DMA irq handler. pl011_int is occurred just before it goes inside spin_lock_irq. When it returns to the callback, DMA buffer already has been flushed. Then, pl011_dma_rx_chars gets invalid data. So I add check for the residue as the patch bellow. Signed-off-by: Chanho Min Acked-by: Linus Walleij Signed-off-by: Greg Kroah-Hartman diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 6800f5f..cc3ea06 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -827,7 +827,12 @@ static void pl011_dma_rx_callback(void *data) { struct uart_amba_port *uap = data; struct pl011_dmarx_data *dmarx = &uap->dmarx; + struct dma_chan *rxchan = dmarx->chan; bool lastbuf = dmarx->use_buf_b; + struct pl011_sgbuf *sgbuf = dmarx->use_buf_b ? + &dmarx->sgbuf_b : &dmarx->sgbuf_a; + size_t pending; + struct dma_tx_state state; int ret; /* @@ -838,11 +843,21 @@ static void pl011_dma_rx_callback(void *data) * we immediately trigger the next DMA job. */ spin_lock_irq(&uap->port.lock); + /* + * Rx data can be taken by the UART interrupts during + * the DMA irq handler. So we check the residue here. + */ + rxchan->device->device_tx_status(rxchan, dmarx->cookie, &state); + pending = sgbuf->sg.length - state.residue; + BUG_ON(pending > PL011_DMA_BUFFER_SIZE); + /* Then we terminate the transfer - we now know our residue */ + dmaengine_terminate_all(rxchan); + uap->dmarx.running = false; dmarx->use_buf_b = !lastbuf; ret = pl011_dma_rx_trigger_dma(uap); - pl011_dma_rx_chars(uap, PL011_DMA_BUFFER_SIZE, lastbuf, false); + pl011_dma_rx_chars(uap, pending, lastbuf, false); spin_unlock_irq(&uap->port.lock); /* * Do this check after we picked the DMA chars so we don't -- cgit v0.10.2