From: Thomas Gleixner <tglx@linutronix.de>
To: linux-can <linux-can@vger.kernel.org>
Cc: Alexander Stein <alexander.stein@systec-electronic.com>,
Oliver Hartkopp <socketcan@hartkopp.net>,
Marc Kleine-Budde <mkl@pengutronix.de>,
Wolfgang Grandegger <wg@grandegger.com>, Mark <mark5@del-llc.com>
Subject: [patch V2 10/21] can: c_can: Get rid of pointless interrupts
Date: Fri, 11 Apr 2014 08:13:15 -0000 [thread overview]
Message-ID: <20140411080652.184106842@linutronix.de> (raw)
In-Reply-To: 20140411080547.845836199@linutronix.de
[-- Attachment #1: can-c-can-get-rid-of-pointless-interrupts.patch --]
[-- Type: text/plain, Size: 8406 bytes --]
The driver handles pointlessly TWO interrupts per packet. The reason
is that it enables the status interrupt which fires for each rx and tx
packet and it enables the per message object interrupts as well.
The status interrupt merily acks or in case of D_CAN ignores the TX/RX
state and then the message object interrupt fires.
The message objects interrupts are only useful if all message objects
have hardware filters activated.
But we don't have that and its not simple to implement in that driver
without rewriting it completely.
So we can ditch the message object interrupts and handle the RX/TX
right away from the status interrupt. Instead of TWO we handle ONE.
Note: We must keep the TXIE/RXIE bits in the message buffers because
the status interrupt alone is not reliable enough in corner cases.
If we ever have the need for HW filtering, then this code needs a
complete overhaul and we can think about it then. For now we prefer a
lower interrupt load.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
drivers/net/can/c_can/c_can.c | 122 ++++++++++++++++--------------------------
drivers/net/can/c_can/c_can.h | 3 -
2 files changed, 48 insertions(+), 77 deletions(-)
Index: linux-2.6/drivers/net/can/c_can/c_can.c
===================================================================
--- linux-2.6.orig/drivers/net/can/c_can/c_can.c
+++ linux-2.6/drivers/net/can/c_can/c_can.c
@@ -593,7 +593,7 @@ static void c_can_configure_msg_objects(
/* setup receive message objects */
for (i = C_CAN_MSG_OBJ_RX_FIRST; i < C_CAN_MSG_OBJ_RX_LAST; i++)
c_can_setup_receive_object(dev, IF_RX, i, 0, 0,
- (IF_MCONT_RXIE | IF_MCONT_UMASK) & ~IF_MCONT_EOB);
+ IF_MCONT_RXIE | IF_MCONT_UMASK);
c_can_setup_receive_object(dev, IF_RX, C_CAN_MSG_OBJ_RX_LAST, 0, 0,
IF_MCONT_EOB | IF_MCONT_RXIE | IF_MCONT_UMASK);
@@ -649,8 +649,9 @@ static int c_can_start(struct net_device
priv->can.state = CAN_STATE_ERROR_ACTIVE;
- /* reset tx helper pointers */
+ /* reset tx helper pointers and the rx mask */
priv->tx_next = priv->tx_echo = 0;
+ priv->rxmasked = 0;
return 0;
}
@@ -823,9 +824,13 @@ static int c_can_read_objects(struct net
/* read the data from the message object */
c_can_read_msg_object(dev, IF_RX, ctrl);
- if (obj == C_CAN_MSG_RX_LOW_LAST)
+ if (obj < C_CAN_MSG_RX_LOW_LAST)
+ priv->rxmasked |= BIT(obj - 1);
+ else if (obj == C_CAN_MSG_RX_LOW_LAST) {
+ priv->rxmasked = 0;
/* activate all lower message objects */
c_can_activate_all_lower_rx_msg_obj(dev, IF_RX);
+ }
pkts++;
quota--;
@@ -870,7 +875,8 @@ static int c_can_do_rx_poll(struct net_d
while (quota > 0) {
if (!pend) {
- pend = priv->read_reg(priv, C_CAN_INTPND1_REG);
+ pend = priv->read_reg(priv, C_CAN_NEWDAT1_REG);
+ pend &= ~priv->rxmasked;
if (!pend)
break;
/*
@@ -1040,10 +1046,6 @@ static int c_can_handle_bus_err(struct n
break;
}
- /* set a `lec` value so that we can check for updates later */
- if (priv->type != BOSCH_D_CAN)
- priv->write_reg(priv, C_CAN_STS_REG, LEC_UNUSED);
-
stats->rx_packets++;
stats->rx_bytes += cf->can_dlc;
netif_receive_skb(skb);
@@ -1052,79 +1054,50 @@ static int c_can_handle_bus_err(struct n
static int c_can_poll(struct napi_struct *napi, int quota)
{
- u16 irqstatus;
- int work_done = 0;
struct net_device *dev = napi->dev;
struct c_can_priv *priv = netdev_priv(dev);
+ u16 curr, last = priv->last_status;
+ int work_done = 0;
- irqstatus = priv->irqstatus;
- if (!irqstatus)
- goto end;
-
- /* status events have the highest priority */
- if (irqstatus == STATUS_INTERRUPT) {
- priv->current_status = priv->read_reg(priv,
- C_CAN_STS_REG);
-
- /* handle Tx/Rx events */
- if (priv->current_status & STATUS_TXOK &&
- priv->type != BOSCH_D_CAN)
- priv->write_reg(priv, C_CAN_STS_REG,
- priv->current_status & ~STATUS_TXOK);
-
- if (priv->current_status & STATUS_RXOK &&
- priv->type != BOSCH_D_CAN)
- priv->write_reg(priv, C_CAN_STS_REG,
- priv->current_status & ~STATUS_RXOK);
-
- /* handle state changes */
- if ((priv->current_status & STATUS_EWARN) &&
- (!(priv->last_status & STATUS_EWARN))) {
- netdev_dbg(dev, "entered error warning state\n");
- work_done += c_can_handle_state_change(dev,
- C_CAN_ERROR_WARNING);
- }
- if ((priv->current_status & STATUS_EPASS) &&
- (!(priv->last_status & STATUS_EPASS))) {
- netdev_dbg(dev, "entered error passive state\n");
- work_done += c_can_handle_state_change(dev,
- C_CAN_ERROR_PASSIVE);
- }
- if ((priv->current_status & STATUS_BOFF) &&
- (!(priv->last_status & STATUS_BOFF))) {
- netdev_dbg(dev, "entered bus off state\n");
- work_done += c_can_handle_state_change(dev,
- C_CAN_BUS_OFF);
- goto end;
- }
+ priv->last_status = curr = priv->read_reg(priv, C_CAN_STS_REG);
+ /* Ack status on C_CAN. D_CAN is self clearing */
+ if (priv->type != BOSCH_D_CAN)
+ priv->write_reg(priv, C_CAN_STS_REG, LEC_UNUSED);
- /* handle bus recovery events */
- if ((!(priv->current_status & STATUS_BOFF)) &&
- (priv->last_status & STATUS_BOFF)) {
- netdev_dbg(dev, "left bus off state\n");
- priv->can.state = CAN_STATE_ERROR_ACTIVE;
- }
- if ((!(priv->current_status & STATUS_EPASS)) &&
- (priv->last_status & STATUS_EPASS)) {
- netdev_dbg(dev, "left error passive state\n");
- priv->can.state = CAN_STATE_ERROR_ACTIVE;
- }
+ /* handle state changes */
+ if ((curr & STATUS_EWARN) && (!(last & STATUS_EWARN))) {
+ netdev_dbg(dev, "entered error warning state\n");
+ work_done += c_can_handle_state_change(dev, C_CAN_ERROR_WARNING);
+ }
- priv->last_status = priv->current_status;
+ if ((curr & STATUS_EPASS) && (!(last & STATUS_EPASS))) {
+ netdev_dbg(dev, "entered error passive state\n");
+ work_done += c_can_handle_state_change(dev, C_CAN_ERROR_PASSIVE);
+ }
- /* handle lec errors on the bus */
- work_done += c_can_handle_bus_err(dev,
- priv->current_status & LEC_MASK);
- } else if ((irqstatus >= C_CAN_MSG_OBJ_RX_FIRST) &&
- (irqstatus <= C_CAN_MSG_OBJ_RX_LAST)) {
- /* handle events corresponding to receive message objects */
- work_done += c_can_do_rx_poll(dev, (quota - work_done));
- } else if ((irqstatus >= C_CAN_MSG_OBJ_TX_FIRST) &&
- (irqstatus <= C_CAN_MSG_OBJ_TX_LAST)) {
- /* handle events corresponding to transmit message objects */
- c_can_do_tx(dev);
+ if ((curr & STATUS_BOFF) && (!(last & STATUS_BOFF))) {
+ netdev_dbg(dev, "entered bus off state\n");
+ work_done += c_can_handle_state_change(dev, C_CAN_BUS_OFF);
+ goto end;
}
+ /* handle bus recovery events */
+ if ((!(curr & STATUS_BOFF)) && (last & STATUS_BOFF)) {
+ netdev_dbg(dev, "left bus off state\n");
+ priv->can.state = CAN_STATE_ERROR_ACTIVE;
+ }
+ if ((!(curr & STATUS_EPASS)) && (last & STATUS_EPASS)) {
+ netdev_dbg(dev, "left error passive state\n");
+ priv->can.state = CAN_STATE_ERROR_ACTIVE;
+ }
+
+ /* handle lec errors on the bus */
+ work_done += c_can_handle_bus_err(dev, curr & LEC_MASK);
+
+ /* Handle Tx/Rx events. We do this unconditionally */
+ work_done += c_can_do_rx_poll(dev, (quota - work_done));
+ c_can_do_tx(dev);
+
end:
if (work_done < quota) {
napi_complete(napi);
@@ -1141,8 +1114,7 @@ static irqreturn_t c_can_isr(int irq, vo
struct net_device *dev = (struct net_device *)dev_id;
struct c_can_priv *priv = netdev_priv(dev);
- priv->irqstatus = priv->read_reg(priv, C_CAN_INT_REG);
- if (!priv->irqstatus)
+ if (!priv->read_reg(priv, C_CAN_INT_REG))
return IRQ_NONE;
/* disable all interrupts and schedule the NAPI */
Index: linux-2.6/drivers/net/can/c_can/c_can.h
===================================================================
--- linux-2.6.orig/drivers/net/can/c_can/c_can.h
+++ linux-2.6/drivers/net/can/c_can/c_can.h
@@ -185,7 +185,6 @@ struct c_can_priv {
struct device *device;
spinlock_t xmit_lock;
int tx_object;
- int current_status;
int last_status;
u16 (*read_reg) (struct c_can_priv *priv, enum reg index);
void (*write_reg) (struct c_can_priv *priv, enum reg index, u16 val);
@@ -195,11 +194,11 @@ struct c_can_priv {
unsigned int tx_next;
unsigned int tx_echo;
void *priv; /* for board-specific data */
- u16 irqstatus;
enum c_can_dev_id type;
u32 __iomem *raminit_ctrlreg;
unsigned int instance;
void (*raminit) (const struct c_can_priv *priv, bool enable);
+ u32 rxmasked;
u32 dlc[C_CAN_MSG_OBJ_TX_NUM];
};
next prev parent reply other threads:[~2014-04-11 8:13 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-11 8:13 [patch V2 00/21] can: c_can: Another pile of fixes and improvements Thomas Gleixner
2014-04-11 8:13 ` [patch V2 02/21] can: c_can: Fix startup logic Thomas Gleixner
2014-04-11 8:13 ` [patch V2 01/21] can: c_can_pci: Set the type of the IP core Thomas Gleixner
2014-04-11 8:13 ` [patch V2 03/21] can: c_can: Make bus off interrupt disable logic work Thomas Gleixner
2014-04-11 8:13 ` [patch V2 05/21] can: c_can: Handle state change correctly Thomas Gleixner
2014-04-11 8:13 ` [patch V2 04/21] can: c_can: Do not access skb after net_receive_skb() Thomas Gleixner
2014-04-11 8:13 ` [patch V2 07/21] can: c_can: Always update error stats Thomas Gleixner
2014-04-11 8:13 ` [patch V2 06/21] can: c_can: Fix berr reporting Thomas Gleixner
2014-04-11 8:13 ` [patch V2 08/21] can: c_can: Simplify buffer reenabling Thomas Gleixner
2014-04-11 8:13 ` [patch V2 09/21] can: c_can: Avoid status register update for D_CAN Thomas Gleixner
2014-04-11 8:13 ` Thomas Gleixner [this message]
2014-04-11 8:13 ` [patch V2 11/21] can: c_can : Disable rx split as workaround Thomas Gleixner
2014-04-11 8:13 ` [patch V2 12/21] can: c_can": Work around C_CAN RX wreckage Thomas Gleixner
2014-04-14 8:38 ` Alexander Stein
2014-04-14 20:13 ` Thomas Gleixner
2014-04-14 20:17 ` Marc Kleine-Budde
2014-04-11 8:13 ` [patch V2 13/21] can: c_can: Cleanup irq enable/disable Thomas Gleixner
2014-04-11 8:13 ` [patch V2 15/21] can: c_can Cleanup setup of receive buffers Thomas Gleixner
2014-04-11 8:13 ` [patch V2 14/21] can: c_can: Cleanup c_can_read_msg_object() Thomas Gleixner
2014-04-11 8:13 ` [patch V2 16/21] can: c_can: Cleanup c_can_inval_msg_object() Thomas Gleixner
2014-04-11 8:13 ` [patch V2 17/21] can: c_can: Cleanup c_can_msg_obj_put/get() Thomas Gleixner
2014-04-11 8:13 ` [patch V2 19/21] can: c_can: Use proper u32 variables in c_can_write_msg_object() Thomas Gleixner
2014-04-11 8:13 ` [patch V2 18/21] can: c_can: Cleanup c_can_write_msg_object() Thomas Gleixner
2014-04-11 8:13 ` [patch V2 20/21] can: c_can: Remove tx locking Thomas Gleixner
2014-04-11 8:13 ` [patch V2 21/21] can: c_can: Speed up tx buffer invalidation Thomas Gleixner
2014-04-14 8:38 ` [patch V2 00/21] can: c_can: Another pile of fixes and improvements Alexander Stein
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