fsi/fsi-master-gpio: Implement CRC error recovery
The FSI protocol defines two modes of recovery from CRC errors, this implements both: - If the device returns an ECRC (it detected a CRC error in the command), then we simply issue the command again. - If the master detects a CRC error in the response, we send an E_POLL command which requests a resend of the response without actually re-executing the command (which could otherwise have unwanted side effects such as dequeuing a FIFO twice). Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Reviewed-by: Christopher Bostic <cbostic@linux.vnet.ibm.com> Tested-by: Joel Stanley <joel@jms.id.au> --- Note: This was actually tested by removing some of my fixes, thus causing us to hit occasional CRC errors during high LPC activity.
This commit is contained in:
Benjamin Herrenschmidt
Родитель
0e82e5c1fa
Коммит
4e56828a5d
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@ -22,20 +22,23 @@
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#define FSI_BREAK_CLOCKS 256 /* Number of clocks to issue break */
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#define FSI_POST_BREAK_CLOCKS 16000 /* Number clocks to set up cfam */
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#define FSI_INIT_CLOCKS 5000 /* Clock out any old data */
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#define FSI_GPIO_DPOLL_CLOCKS 50 /* < 21 will cause slave to hang */
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#define FSI_GPIO_EPOLL_CLOCKS 50 /* Number of clocks for E_POLL retry */
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#define FSI_GPIO_STD_DELAY 10 /* Standard GPIO delay in nS */
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/* todo: adjust down as low as */
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/* possible or eliminate */
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#define FSI_CRC_ERR_RETRIES 10
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#define FSI_GPIO_CMD_DPOLL 0x2
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#define FSI_GPIO_CMD_EPOLL 0x3
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#define FSI_GPIO_CMD_TERM 0x3f
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#define FSI_GPIO_CMD_ABS_AR 0x4
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#define FSI_GPIO_CMD_REL_AR 0x5
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#define FSI_GPIO_CMD_SAME_AR 0x3 /* but only a 2-bit opcode... */
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#define FSI_GPIO_DPOLL_CLOCKS 50 /* < 21 will cause slave to hang */
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/* Bus errors */
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#define FSI_GPIO_ERR_BUSY 1 /* Slave stuck in busy state */
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/* Slave responses */
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#define FSI_GPIO_RESP_ACK 0 /* Success */
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#define FSI_GPIO_RESP_BUSY 1 /* Slave busy */
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#define FSI_GPIO_RESP_ERRA 2 /* Any (misc) Error */
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#define FSI_GPIO_RESP_ERRC 3 /* Slave reports master CRC error */
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#define FSI_GPIO_MTOE 4 /* Master time out error */
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@ -330,6 +333,16 @@ static void build_dpoll_command(struct fsi_gpio_msg *cmd, uint8_t slave_id)
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msg_push_crc(cmd);
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}
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static void build_epoll_command(struct fsi_gpio_msg *cmd, uint8_t slave_id)
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{
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cmd->bits = 0;
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cmd->msg = 0;
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msg_push_bits(cmd, slave_id, 2);
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msg_push_bits(cmd, FSI_GPIO_CMD_EPOLL, 3);
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msg_push_crc(cmd);
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}
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static void echo_delay(struct fsi_master_gpio *master)
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{
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set_sda_output(master, 1);
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@ -355,6 +368,12 @@ static void fsi_master_gpio_error(struct fsi_master_gpio *master, int error)
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}
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/*
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* Note: callers rely specifically on this returning -EAGAIN for
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* a CRC error detected in the response. Use other error code
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* for other situations. It will be converted to something else
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* higher up the stack before it reaches userspace.
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*/
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static int read_one_response(struct fsi_master_gpio *master,
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uint8_t data_size, struct fsi_gpio_msg *msgp, uint8_t *tagp)
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{
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@ -379,7 +398,7 @@ static int read_one_response(struct fsi_master_gpio *master,
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"Master time out waiting for response\n");
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fsi_master_gpio_error(master, FSI_GPIO_MTOE);
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spin_unlock_irqrestore(&master->bit_lock, flags);
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return -EIO;
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return -ETIMEDOUT;
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}
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msg.bits = 0;
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@ -405,7 +424,7 @@ static int read_one_response(struct fsi_master_gpio *master,
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if (crc) {
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dev_dbg(master->dev, "ERR response CRC\n");
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fsi_master_gpio_error(master, FSI_GPIO_CRC_INVAL);
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return -EIO;
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return -EAGAIN;
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}
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if (msgp)
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@ -451,11 +470,33 @@ static int poll_for_response(struct fsi_master_gpio *master,
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unsigned long flags;
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uint8_t tag;
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uint8_t *data_byte = data;
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int crc_err_retries = 0;
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retry:
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rc = read_one_response(master, size, &response, &tag);
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if (rc)
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return rc;
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/* Handle retries on CRC errors */
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if (rc == -EAGAIN) {
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/* Too many retries ? */
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if (crc_err_retries++ > FSI_CRC_ERR_RETRIES) {
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/*
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* Pass it up as a -EIO otherwise upper level will retry
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* the whole command which isn't what we want here.
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*/
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rc = -EIO;
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goto fail;
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}
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dev_dbg(master->dev,
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"CRC error retry %d\n", crc_err_retries);
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trace_fsi_master_gpio_crc_rsp_error(master);
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build_epoll_command(&cmd, slave);
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spin_lock_irqsave(&master->bit_lock, flags);
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clock_zeros(master, FSI_GPIO_EPOLL_CLOCKS);
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serial_out(master, &cmd);
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echo_delay(master);
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spin_unlock_irqrestore(&master->bit_lock, flags);
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goto retry;
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} else if (rc)
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goto fail;
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switch (tag) {
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case FSI_GPIO_RESP_ACK:
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@ -496,18 +537,21 @@ retry:
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break;
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case FSI_GPIO_RESP_ERRA:
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case FSI_GPIO_RESP_ERRC:
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dev_dbg(master->dev, "ERR%c received: 0x%x\n",
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tag == FSI_GPIO_RESP_ERRA ? 'A' : 'C',
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(int)response.msg);
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dev_dbg(master->dev, "ERRA received: 0x%x\n", (int)response.msg);
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fsi_master_gpio_error(master, response.msg);
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rc = -EIO;
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break;
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case FSI_GPIO_RESP_ERRC:
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dev_dbg(master->dev, "ERRC received: 0x%x\n", (int)response.msg);
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fsi_master_gpio_error(master, response.msg);
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trace_fsi_master_gpio_crc_cmd_error(master);
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rc = -EAGAIN;
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break;
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}
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if (busy_count > 0)
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trace_fsi_master_gpio_poll_response_busy(master, busy_count);
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fail:
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/* Clock the slave enough to be ready for next operation */
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spin_lock_irqsave(&master->bit_lock, flags);
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clock_zeros(master, FSI_GPIO_PRIME_SLAVE_CLOCKS);
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@ -536,11 +580,21 @@ static int send_request(struct fsi_master_gpio *master,
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static int fsi_master_gpio_xfer(struct fsi_master_gpio *master, uint8_t slave,
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struct fsi_gpio_msg *cmd, size_t resp_len, void *resp)
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{
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int rc;
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int rc = -EAGAIN, retries = 0;
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rc = send_request(master, cmd);
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if (!rc)
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while ((retries++) < FSI_CRC_ERR_RETRIES) {
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rc = send_request(master, cmd);
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if (rc)
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break;
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rc = poll_for_response(master, slave, resp_len, resp);
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if (rc != -EAGAIN)
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break;
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rc = -EIO;
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dev_warn(master->dev, "ECRC retry %d\n", retries);
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/* Pace it a bit before retry */
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msleep(1);
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}
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return rc;
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}
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@ -64,6 +64,33 @@ TRACE_EVENT(fsi_master_gpio_break,
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)
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);
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TRACE_EVENT(fsi_master_gpio_crc_cmd_error,
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TP_PROTO(const struct fsi_master_gpio *master),
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TP_ARGS(master),
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TP_STRUCT__entry(
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__field(int, master_idx)
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),
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TP_fast_assign(
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__entry->master_idx = master->master.idx;
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),
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TP_printk("fsi-gpio%d ----CRC command retry---",
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__entry->master_idx
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)
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);
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TRACE_EVENT(fsi_master_gpio_crc_rsp_error,
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TP_PROTO(const struct fsi_master_gpio *master),
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TP_ARGS(master),
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TP_STRUCT__entry(
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__field(int, master_idx)
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),
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TP_fast_assign(
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__entry->master_idx = master->master.idx;
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),
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TP_printk("fsi-gpio%d ----CRC response---",
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__entry->master_idx
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)
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);
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TRACE_EVENT(fsi_master_gpio_poll_response_busy,
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TP_PROTO(const struct fsi_master_gpio *master, int busy),
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