drv: wait for timing config to be applied

The update is not immediate, we need to monitor UPD_DONE to be reassured that values are applied and we can continue. If this does not happen, then it is a serious hardware problem. That's why I chose to use WARN_ON. By returning and error code, we will get a ZIO_ALARM_LOST_TRIGGER, that userspace needs to check. Signed-off-by: Federico Vaga <federico.vaga@cern.ch>

drv: wait for timing config to be applied
The update is not immediate, we need to monitor UPD_DONE to be reassured that values are applied and we can continue. If this does not happen, then it is a serious hardware problem. That's why I chose to use WARN_ON. By returning and error code, we will get a ZIO_ALARM_LOST_TRIGGER, that userspace needs to check. Signed-off-by: Federico Vaga <federico.vaga@cern.ch>
1938dde0 · Federico Vaga · ab8edc42 · 1938dde0 · 1938dde0
Commit 1938dde0 authored Oct 18, 2023 by Federico Vaga
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Showing with 15 additions and 2 deletions

fd-zio.c software/kernel/fd-zio.c +13 -2

fine-delay.h software/kernel/fine-delay.h +2 -0

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--- a/software/kernel/fd-zio.c
+++ b/software/kernel/fd-zio.c
@@ -513,6 +513,7 @@ static int __fd_zio_output(struct fd_dev *fd, int index1_4, uint32_t *attrs)
 	int mode = attrs[FD_ATTR_OUT_MODE];
 	int rep = attrs[FD_ATTR_OUT_REP];
 	int dcr = 0;
+	unsigned long timeout;

 	if (mode == FD_OUT_MODE_DELAY || mode == FD_OUT_MODE_DISABLED) {
 		if(rep < 0 || rep > 16) /* delay mode allows trains of 1 to 16 pulses. */
@@ -629,6 +630,13 @@ static int __fd_zio_output(struct fd_dev *fd, int index1_4, uint32_t *attrs)
 	/* Update the time stamps according to start/end registers */
 	fd_ch_writel(fd, ch, dcr | FD_DCR_UPDATE, FD_REG_DCR);

+	timeout = jiffies + msecs_to_jiffies(10);
+	while (!(fd_ch_readl(fd, ch, FD_REG_DCR) & FD_DCR_UPD_DONE)) {
+		if (WARN_ON(time_after(jiffies, timeout)))
+			return -ETIMEDOUT;
+		cpu_relax();
+	}
+
 	/* Enable channel output */
 	if (mode == FD_OUT_MODE_DELAY) {
 		fd_ch_writel(fd, ch, dcr | FD_DCR_ENABLE, FD_REG_DCR);
@@ -642,7 +650,7 @@ static int __fd_zio_output(struct fd_dev *fd, int index1_4, uint32_t *attrs)
 /* This is called on user write */
 static int fd_zio_output(struct zio_cset *cset)
 {
-	int i;
+	int i, err;
 	struct fd_dev *fd;
 	struct zio_control *ctrl;

@@ -656,7 +664,10 @@ static int fd_zio_output(struct zio_cset *cset)
 			printk("%08x%c", ctrl->attr_channel.ext_val[i],
 			       i == FD_ATTR_OUT__LAST -1 ? '\n' : ' ');
 	}
-	return __fd_zio_output(fd, cset->index, ctrl->attr_channel.ext_val);
+	err = __fd_zio_output(fd, cset->index, ctrl->attr_channel.ext_val);
+	if (err)
+		cset->chan[0].current_ctrl->drv_alarms |= FD_ZIO_ALARM_FAIL_CONFIG;
+	return err;
 }

 /*

--- a/software/kernel/fine-delay.h
+++ b/software/kernel/fine-delay.h
@@ -162,6 +162,8 @@ struct fd_calibration { /* All of these are big endian */
 	uint32_t vcxo_default_tune;
 };

+#define FD_ZIO_ALARM_FAIL_CONFIG (1 << 0) /* Delay configuration failed */
+
 #ifdef __KERNEL__ /* All the rest is only of kernel users */
 #include <linux/spinlock.h>
 #include <linux/timer.h>