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Commit 33d9b8b2 authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
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serial: 8250: Extract IIR logic steering from rx dma 



Using fake IIR values to perform rx dma operations unnecessarily
conflates separate operations, stopping in-progress dma with starting
new dma.

Introduce serial8250_rx_dma_flush() to handle stopping in-progress dma
[omap8250 already has equivalent omap_8250_rx_dma_flush()].
Replace rx_dma(UART_IIR_RX_TIMEOUT) with the equivalent *_rx_dma_flush(),
and rx_dma(0) with the equivalent *_rx_dma(). Handle IIR steering
in the irq handler with handle_rx_dma() helper.

Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Reviewed-by: default avatarHeikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent b74fdd23

drivers/tty/serial/8250/8250.h

+5 −3
Original line number Diff line number Diff line
@@ -17,7 +17,7 @@ 


struct uart_8250_dma {

	int (*tx_dma)(struct uart_8250_port *p);

	int (*rx_dma)(struct uart_8250_port *p, unsigned int iir);

	int (*rx_dma)(struct uart_8250_port *p);



	/* Filter function */

	dma_filter_fn		fn;
@@ -189,7 +189,8 @@ static inline int is_omap1510_8250(struct uart_8250_port *pt) 


#ifdef CONFIG_SERIAL_8250_DMA

extern int serial8250_tx_dma(struct uart_8250_port *);

extern int serial8250_rx_dma(struct uart_8250_port *, unsigned int iir);

extern int serial8250_rx_dma(struct uart_8250_port *);

extern void serial8250_rx_dma_flush(struct uart_8250_port *);

extern int serial8250_request_dma(struct uart_8250_port *);

extern void serial8250_release_dma(struct uart_8250_port *);

#else
@@ -197,10 +198,11 @@ static inline int serial8250_tx_dma(struct uart_8250_port *p) 
{

	return -1;

}

static inline int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir)

static inline int serial8250_rx_dma(struct uart_8250_port *p)

{

	return -1;

}

static inline void serial8250_rx_dma_flush(struct uart_8250_port *p) { }

static inline int serial8250_request_dma(struct uart_8250_port *p)

{

	return -1;

drivers/tty/serial/8250/8250_dma.c

+12 −20
Original line number Diff line number Diff line
@@ -110,30 +110,11 @@ int serial8250_tx_dma(struct uart_8250_port *p) 
	return ret;

}



int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir)

int serial8250_rx_dma(struct uart_8250_port *p)

{

	struct uart_8250_dma		*dma = p->dma;

	struct dma_async_tx_descriptor	*desc;



	switch (iir & 0x3f) {

	case UART_IIR_RLSI:

		/* 8250_core handles errors and break interrupts */

		return -EIO;

	case UART_IIR_RX_TIMEOUT:

		/*

		 * If RCVR FIFO trigger level was not reached, complete the

		 * transfer and let 8250_core copy the remaining data.

		 */

		if (dma->rx_running) {

			dmaengine_pause(dma->rxchan);

			__dma_rx_complete(p);

			dmaengine_terminate_all(dma->rxchan);

		}

		return -ETIMEDOUT;

	default:

		break;

	}



	if (dma->rx_running)

		return 0;
@@ -154,6 +135,17 @@ int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir) 
	return 0;

}



void serial8250_rx_dma_flush(struct uart_8250_port *p)

{

	struct uart_8250_dma *dma = p->dma;



	if (dma->rx_running) {

		dmaengine_pause(dma->rxchan);

		__dma_rx_complete(p);

		dmaengine_terminate_all(dma->rxchan);

	}

}



int serial8250_request_dma(struct uart_8250_port *p)

{

	struct uart_8250_dma	*dma = p->dma;

drivers/tty/serial/8250/8250_omap.c

+28 −39
Original line number Diff line number Diff line
@@ -115,6 +115,12 @@ struct omap8250_priv { 
	bool rx_dma_broken;

};



#ifdef CONFIG_SERIAL_8250_DMA

static void omap_8250_rx_dma_flush(struct uart_8250_port *p);

#else

static inline void omap_8250_rx_dma_flush(struct uart_8250_port *p) { }

#endif



static u32 uart_read(struct uart_8250_port *up, u32 reg)

{

	return readl(up->port.membase + (reg << up->port.regshift));
@@ -635,7 +641,7 @@ static int omap_8250_startup(struct uart_port *port) 
	serial_out(up, UART_OMAP_WER, priv->wer);



	if (up->dma)

		up->dma->rx_dma(up, 0);

		up->dma->rx_dma(up);



	pm_runtime_mark_last_busy(port->dev);

	pm_runtime_put_autosuspend(port->dev);
@@ -654,7 +660,7 @@ static void omap_8250_shutdown(struct uart_port *port) 


	flush_work(&priv->qos_work);

	if (up->dma)

		up->dma->rx_dma(up, UART_IIR_RX_TIMEOUT);

		omap_8250_rx_dma_flush(up);



	pm_runtime_get_sync(port->dev);
@@ -742,7 +748,7 @@ static void omap_8250_unthrottle(struct uart_port *port) 
}



#ifdef CONFIG_SERIAL_8250_DMA

static int omap_8250_rx_dma(struct uart_8250_port *p, unsigned int iir);

static int omap_8250_rx_dma(struct uart_8250_port *p);



static void __dma_rx_do_complete(struct uart_8250_port *p)

{
@@ -778,7 +784,7 @@ static void __dma_rx_do_complete(struct uart_8250_port *p) 
static void __dma_rx_complete(void *param)

{

	__dma_rx_do_complete(param);

	omap_8250_rx_dma(param, 0);

	omap_8250_rx_dma(param);

}



static void omap_8250_rx_dma_flush(struct uart_8250_port *p)
@@ -804,7 +810,7 @@ static void omap_8250_rx_dma_flush(struct uart_8250_port *p) 
	__dma_rx_do_complete(p);

}



static int omap_8250_rx_dma(struct uart_8250_port *p, unsigned int iir)

static int omap_8250_rx_dma(struct uart_8250_port *p)

{

	struct omap8250_priv		*priv = p->port.private_data;

	struct uart_8250_dma            *dma = p->dma;
@@ -812,35 +818,6 @@ static int omap_8250_rx_dma(struct uart_8250_port *p, unsigned int iir) 
	struct dma_async_tx_descriptor  *desc;

	unsigned long			flags;



	switch (iir & 0x3f) {

	case UART_IIR_RLSI:

		/* 8250_core handles errors and break interrupts */

		omap_8250_rx_dma_flush(p);

		return -EIO;

	case UART_IIR_RX_TIMEOUT:

		/*

		 * If RCVR FIFO trigger level was not reached, complete the

		 * transfer and let 8250_core copy the remaining data.

		 */

		omap_8250_rx_dma_flush(p);

		return -ETIMEDOUT;

	case UART_IIR_RDI:

		/*

		 * The OMAP UART is a special BEAST. If we receive RDI we _have_

		 * a DMA transfer programmed but it didn't work. One reason is

		 * that we were too slow and there were too many bytes in the

		 * FIFO, the UART counted wrong and never kicked the DMA engine

		 * to do anything. That means once we receive RDI on OMAP then

		 * the DMA won't do anything soon so we have to cancel the DMA

		 * transfer and purge the FIFO manually.

		 */

		omap_8250_rx_dma_flush(p);

		return -ETIMEDOUT;



	default:

		break;

	}



	if (priv->rx_dma_broken)

		return -EINVAL;
@@ -1014,6 +991,18 @@ static int omap_8250_tx_dma(struct uart_8250_port *p) 
	return ret;

}



static bool handle_rx_dma(struct uart_8250_port *up, unsigned int iir)

{

	switch (iir & 0x3f) {

	case UART_IIR_RLSI:

	case UART_IIR_RX_TIMEOUT:

	case UART_IIR_RDI:

		omap_8250_rx_dma_flush(up);

		return true;

	}

	return omap_8250_rx_dma(up);

}



/*

 * This is mostly serial8250_handle_irq(). We have a slightly different DMA

 * hoook for RX/TX and need different logic for them in the ISR. Therefore we
@@ -1039,9 +1028,9 @@ static int omap_8250_dma_handle_irq(struct uart_port *port) 
	status = serial_port_in(port, UART_LSR);



	if (status & (UART_LSR_DR | UART_LSR_BI)) {

		if (omap_8250_rx_dma(up, iir)) {

		if (handle_rx_dma(up, iir)) {

			status = serial8250_rx_chars(up, status);

			omap_8250_rx_dma(up, 0);

			omap_8250_rx_dma(up);

		}

	}

	serial8250_modem_status(up);
@@ -1072,7 +1061,7 @@ static bool the_no_dma_filter_fn(struct dma_chan *chan, void *param) 


#else



static inline int omap_8250_rx_dma(struct uart_8250_port *p, unsigned int iir)

static inline int omap_8250_rx_dma(struct uart_8250_port *p)

{

	return -EINVAL;

}
@@ -1383,7 +1372,7 @@ static int omap8250_runtime_suspend(struct device *dev) 
	}



	if (up->dma && up->dma->rxchan)

		omap_8250_rx_dma(up, UART_IIR_RX_TIMEOUT);

		omap_8250_rx_dma_flush(up);



	priv->latency = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE;

	schedule_work(&priv->qos_work);
@@ -1406,7 +1395,7 @@ static int omap8250_runtime_resume(struct device *dev) 
		omap8250_restore_regs(up);



	if (up->dma && up->dma->rxchan)

		omap_8250_rx_dma(up, 0);

		omap_8250_rx_dma(up);



	priv->latency = priv->calc_latency;

	schedule_work(&priv->qos_work);

drivers/tty/serial/8250/8250_port.c

+13 −1
Original line number Diff line number Diff line
@@ -1788,6 +1788,18 @@ unsigned int serial8250_modem_status(struct uart_8250_port *up) 
}

EXPORT_SYMBOL_GPL(serial8250_modem_status);



static bool handle_rx_dma(struct uart_8250_port *up, unsigned int iir)

{

	switch (iir & 0x3f) {

	case UART_IIR_RX_TIMEOUT:

		serial8250_rx_dma_flush(up);

		/* fall-through */

	case UART_IIR_RLSI:

		return true;

	}

	return up->dma->rx_dma(up);

}



/*

 * This handles the interrupt from one port.

 */
@@ -1807,7 +1819,7 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir) 
	DEBUG_INTR("status = %x...", status);



	if (status & (UART_LSR_DR | UART_LSR_BI)) {

		if (!up->dma || up->dma->rx_dma(up, iir))

		if (!up->dma || handle_rx_dma(up, iir))

			status = serial8250_rx_chars(up, status);

	}

	serial8250_modem_status(up);