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SubjectRe: [PATCH 2.5] : ir252_nsc_speed_both.diff (don't apply ir255_nsc_speed-4.diff)
From
	Linus,

The subject of this e-mail probably gave it away, but I mixed
up my patches and sent you the *WRONG* patch. Not only it contains a
bug, but it will prevent the subsequent driver patch to apply cleanly.
Please ignore the patch called ir255_nsc_speed-4.diff (or
revert it if you already applied it), and use this one instead.
Sorry for the mistake...

Jean

On Thu, Aug 29, 2002 at 03:49:01PM -0700, jt wrote:
> ir255_nsc_speed-4.diff :
> ----------------------
> o [FEATURE] Cleanly change speed back to 9600bps
> o [CORRECT] Change speed under spinlock/irq disabled
> o [CORRECT] Make sure interrupt handlers don't mess irq mask
> o [CORRECT] Don't change speed if we haven't fully finished to Tx

Correct patch is :

ir252_nsc_speed_both.diff :
-------------------------
o [FEATURE] Cleanly change speed back to 9600bps
o [CORRECT] Change speed under spinlock/irq disabled
o [CORRECT] Make sure interrupt handlers don't mess irq mask
o [CORRECT] Don't change speed if we haven't fully finished to Tx


diff -u -p linux/drivers/net/irda/nsc-ircc.d3.c linux/drivers/net/irda/nsc-ircc.c
--- linux/drivers/net/irda/nsc-ircc.d3.c Fri Aug 23 11:06:10 2002
+++ linux/drivers/net/irda/nsc-ircc.c Fri Aug 23 11:07:06 2002
@@ -130,7 +130,7 @@ static int nsc_ircc_hard_xmit_sir(struc
static int nsc_ircc_hard_xmit_fir(struct sk_buff *skb, struct net_device *dev);
static int nsc_ircc_pio_write(int iobase, __u8 *buf, int len, int fifo_size);
static void nsc_ircc_dma_xmit(struct nsc_ircc_cb *self, int iobase);
-static void nsc_ircc_change_speed(struct nsc_ircc_cb *self, __u32 baud);
+static __u8 nsc_ircc_change_speed(struct nsc_ircc_cb *self, __u32 baud);
static void nsc_ircc_interrupt(int irq, void *dev_id, struct pt_regs *regs);
static int nsc_ircc_is_receiving(struct nsc_ircc_cb *self);
static int nsc_ircc_read_dongle_id (int iobase);
@@ -953,17 +953,19 @@ static void nsc_ircc_change_dongle_speed
*
* Change the speed of the device
*
+ * This function *must* be called with irq off and spin-lock.
*/
-static void nsc_ircc_change_speed(struct nsc_ircc_cb *self, __u32 speed)
+static __u8 nsc_ircc_change_speed(struct nsc_ircc_cb *self, __u32 speed)
{
struct net_device *dev = self->netdev;
__u8 mcr = MCR_SIR;
int iobase;
__u8 bank;
+ __u8 ier; /* Interrupt enable register */

IRDA_DEBUG(2, __FUNCTION__ "(), speed=%d\n", speed);

- ASSERT(self != NULL, return;);
+ ASSERT(self != NULL, return 0;);

iobase = self->io.fir_base;

@@ -1038,18 +1040,21 @@ static void nsc_ircc_change_speed(struct
if (speed > 115200) {
/* Install FIR xmit handler */
dev->hard_start_xmit = nsc_ircc_hard_xmit_fir;
- outb(IER_SFIF_IE, iobase+IER);
+ ier = IER_SFIF_IE;
nsc_ircc_dma_receive(self);
} else {
/* Install SIR xmit handler */
dev->hard_start_xmit = nsc_ircc_hard_xmit_sir;
- outb(IER_RXHDL_IE, iobase+IER);
+ ier = IER_RXHDL_IE;
}
+ /* Set our current interrupt mask */
+ outb(ier, iobase+IER);

/* Restore BSR */
outb(bank, iobase+BSR);
- netif_wake_queue(dev);
-
+
+ /* Make sure interrupt handlers keep the proper interrupt mask */
+ return(ier);
}

/*
@@ -1074,20 +1079,36 @@ static int nsc_ircc_hard_xmit_sir(struct

netif_stop_queue(dev);

+ /* Make sure tests *& speed change are atomic */
+ spin_lock_irqsave(&self->lock, flags);
+
/* Check if we need to change the speed */
speed = irda_get_next_speed(skb);
if ((speed != self->io.speed) && (speed != -1)) {
- /* Check for empty frame */
+ /* Check for empty frame. */
if (!skb->len) {
- nsc_ircc_change_speed(self, speed);
+ /* If we just sent a frame, we get called before
+ * the last bytes get out (because of the SIR FIFO).
+ * If this is the case, let interrupt handler change
+ * the speed itself... Jean II */
+ if (self->io.direction == IO_RECV) {
+ nsc_ircc_change_speed(self, speed);
+ /* TODO : For SIR->SIR, the next packet
+ * may get corrupted - Jean II */
+ netif_wake_queue(dev);
+ } else {
+ self->new_speed = speed;
+ /* Queue will be restarted after speed change
+ * to make sure packets gets through the
+ * proper xmit handler - Jean II */
+ }
+ spin_unlock_irqrestore(&self->lock, flags);
dev_kfree_skb(skb);
return 0;
} else
self->new_speed = speed;
}

- spin_lock_irqsave(&self->lock, flags);
-
/* Save current bank */
bank = inb(iobase+BSR);

@@ -1126,20 +1147,38 @@ static int nsc_ircc_hard_xmit_fir(struct

netif_stop_queue(dev);

+ /* Make sure tests *& speed change are atomic */
+ spin_lock_irqsave(&self->lock, flags);
+
/* Check if we need to change the speed */
speed = irda_get_next_speed(skb);
if ((speed != self->io.speed) && (speed != -1)) {
- /* Check for empty frame */
+ /* Check for empty frame. */
if (!skb->len) {
- nsc_ircc_change_speed(self, speed);
+ /* If we are currently transmitting, defer to
+ * interrupt handler. - Jean II */
+ if(self->tx_fifo.len == 0) {
+ nsc_ircc_change_speed(self, speed);
+ netif_wake_queue(dev);
+ } else {
+ self->new_speed = speed;
+ /* Keep queue stopped :
+ * the speed change operation may change the
+ * xmit handler, and we want to make sure
+ * the next packet get through the proper
+ * Tx path, so block the Tx queue until
+ * the speed change has been done.
+ * Jean II */
+ }
+ spin_unlock_irqrestore(&self->lock, flags);
dev_kfree_skb(skb);
return 0;
- } else
+ } else {
+ /* Change speed after current frame */
self->new_speed = speed;
+ }
}

- spin_lock_irqsave(&self->lock, flags);
-
/* Save current bank */
bank = inb(iobase+BSR);

@@ -1209,8 +1248,9 @@ static int nsc_ircc_hard_xmit_fir(struct
nsc_ircc_dma_xmit(self, iobase);
}
out:
- /* Not busy transmitting anymore if window is not full */
- if (self->tx_fifo.free < MAX_TX_WINDOW)
+ /* Not busy transmitting anymore if window is not full,
+ * and if we don't need to change speed */
+ if ((self->tx_fifo.free < MAX_TX_WINDOW) && (self->new_speed == 0))
netif_wake_queue(self->netdev);

/* Restore bank register */
@@ -1334,12 +1374,6 @@ static int nsc_ircc_dma_xmit_complete(st
self->stats.tx_packets++;
}

- /* Check if we need to change the speed */
- if (self->new_speed) {
- nsc_ircc_change_speed(self, self->new_speed);
- self->new_speed = 0;
- }
-
/* Finished with this frame, so prepare for next */
self->tx_fifo.ptr++;
self->tx_fifo.len--;
@@ -1356,8 +1390,9 @@ static int nsc_ircc_dma_xmit_complete(st
self->tx_fifo.tail = self->tx_buff.head;
}

- /* Make sure we have room for more frames */
- if (self->tx_fifo.free < MAX_TX_WINDOW) {
+ /* Make sure we have room for more frames and
+ * that we don't need to change speed */
+ if ((self->tx_fifo.free < MAX_TX_WINDOW) && (self->new_speed == 0)) {
/* Not busy transmitting anymore */
/* Tell the network layer, that we can accept more frames */
netif_wake_queue(self->netdev);
@@ -1634,24 +1669,25 @@ static void nsc_ircc_sir_interrupt(struc
}
/* Check if transmission has completed */
if (eir & EIR_TXEMP_EV) {
- /* Check if we need to change the speed? */
+ /* Turn around and get ready to receive some data */
+ self->io.direction = IO_RECV;
+ self->ier = IER_RXHDL_IE;
+ /* Check if we need to change the speed?
+ * Need to be after self->io.direction to avoid race with
+ * nsc_ircc_hard_xmit_sir() - Jean II */
if (self->new_speed) {
IRDA_DEBUG(2, __FUNCTION__ "(), Changing speed!\n");
- nsc_ircc_change_speed(self, self->new_speed);
+ self->ier = nsc_ircc_change_speed(self,
+ self->new_speed);
self->new_speed = 0;
+ netif_wake_queue(self->netdev);

/* Check if we are going to FIR */
if (self->io.speed > 115200) {
- /* Should wait for status FIFO interrupt */
- self->ier = IER_SFIF_IE;
-
/* No need to do anymore SIR stuff */
return;
}
}
- /* Turn around and get ready to receive some data */
- self->io.direction = IO_RECV;
- self->ier = IER_RXHDL_IE;
}

/* Rx FIFO threshold or timeout */
@@ -1710,19 +1746,36 @@ static void nsc_ircc_fir_interrupt(struc
}
} else if (eir & EIR_DMA_EV) {
/* Finished with all transmissions? */
- if (nsc_ircc_dma_xmit_complete(self)) {
- /* Check if there are more frames to be transmitted */
- if (irda_device_txqueue_empty(self->netdev)) {
- /* Prepare for receive */
- nsc_ircc_dma_receive(self);
-
- self->ier = IER_SFIF_IE;
+ if (nsc_ircc_dma_xmit_complete(self)) {
+ if(self->new_speed != 0) {
+ /* As we stop the Tx queue, the speed change
+ * need to be done when the Tx fifo is
+ * empty. Ask for a Tx done interrupt */
+ self->ier = IER_TXEMP_IE;
+ } else {
+ /* Check if there are more frames to be
+ * transmitted */
+ if (irda_device_txqueue_empty(self->netdev)) {
+ /* Prepare for receive */
+ nsc_ircc_dma_receive(self);
+ self->ier = IER_SFIF_IE;
+ } else
+ WARNING(__FUNCTION__ "(), potential "
+ "Tx queue lockup !\n");
}
} else {
/* Not finished yet, so interrupt on DMA again */
self->ier = IER_DMA_IE;
}
+ } else if (eir & EIR_TXEMP_EV) {
+ /* The Tx FIFO has totally drained out, so now we can change
+ * the speed... - Jean II */
+ self->ier = nsc_ircc_change_speed(self, self->new_speed);
+ self->new_speed = 0;
+ netif_wake_queue(self->netdev);
+ /* Note : nsc_ircc_change_speed() restarted Rx fifo */
}
+
outb(bank, iobase+BSR);
}

-
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