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i2c-taos-evm: Switch echo off to improve performance
When echo is on, we waste time reading back our orders. Switching echo off makes performance much better: SMBus byte data transactions are 47% faster and byte transactions are 24% faster. Signed-off-by: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
parent
6a891a3111
commit
27693ce5f3
1 changed files with 24 additions and 21 deletions
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@ -32,10 +32,12 @@
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#define TAOS_STATE_INIT 0
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#define TAOS_STATE_IDLE 1
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#define TAOS_STATE_SEND 2
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#define TAOS_STATE_EOFF 2
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#define TAOS_STATE_RECV 3
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#define TAOS_CMD_RESET 0x12
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#define TAOS_CMD_ECHO_ON '+'
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#define TAOS_CMD_ECHO_OFF '-'
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static DECLARE_WAIT_QUEUE_HEAD(wq);
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@ -102,17 +104,9 @@ static int taos_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
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/* Send the transaction to the TAOS EVM */
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dev_dbg(&adapter->dev, "Command buffer: %s\n", taos->buffer);
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taos->pos = 0;
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taos->state = TAOS_STATE_SEND;
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serio_write(serio, taos->buffer[0]);
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wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
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msecs_to_jiffies(250));
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if (taos->state != TAOS_STATE_IDLE) {
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dev_err(&adapter->dev, "Transaction failed "
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"(state=%d, pos=%d)\n", taos->state, taos->pos);
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taos->addr = 0;
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return -EIO;
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}
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for (p = taos->buffer; *p; p++)
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serio_write(serio, *p);
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taos->addr = addr;
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/* Start the transaction and read the answer */
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@ -122,7 +116,7 @@ static int taos_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
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wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
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msecs_to_jiffies(150));
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if (taos->state != TAOS_STATE_IDLE
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|| taos->pos != 6) {
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|| taos->pos != 5) {
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dev_err(&adapter->dev, "Transaction timeout (pos=%d)\n",
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taos->pos);
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return -EIO;
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@ -130,7 +124,7 @@ static int taos_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
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dev_dbg(&adapter->dev, "Answer buffer: %s\n", taos->buffer);
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/* Interpret the returned string */
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p = taos->buffer + 2;
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p = taos->buffer + 1;
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p[3] = '\0';
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if (!strcmp(p, "NAK"))
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return -ENODEV;
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@ -173,13 +167,9 @@ static irqreturn_t taos_interrupt(struct serio *serio, unsigned char data,
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wake_up_interruptible(&wq);
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}
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break;
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case TAOS_STATE_SEND:
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if (taos->buffer[++taos->pos])
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serio_write(serio, taos->buffer[taos->pos]);
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else {
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taos->state = TAOS_STATE_IDLE;
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wake_up_interruptible(&wq);
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}
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case TAOS_STATE_EOFF:
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taos->state = TAOS_STATE_IDLE;
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wake_up_interruptible(&wq);
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break;
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case TAOS_STATE_RECV:
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taos->buffer[taos->pos++] = data;
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@ -257,6 +247,19 @@ static int taos_connect(struct serio *serio, struct serio_driver *drv)
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}
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strlcpy(adapter->name, name, sizeof(adapter->name));
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/* Turn echo off for better performance */
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taos->state = TAOS_STATE_EOFF;
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serio_write(serio, TAOS_CMD_ECHO_OFF);
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wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
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msecs_to_jiffies(250));
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if (taos->state != TAOS_STATE_IDLE) {
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err = -ENODEV;
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dev_err(&adapter->dev, "Echo off failed "
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"(state=%d)\n", taos->state);
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goto exit_close;
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}
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err = i2c_add_adapter(adapter);
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if (err)
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goto exit_close;
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