Due to blocking, synchronous, polling driven nature of Barebox's
serial communication handling trying to use two or more serial ports
at high (1Mbaud+) baudrates results in data loss and noticeable
perofmance degradation. This happens as soon as individual message
being sent around start exceeding HW Rx FIFO in size.
A good example of such a usecase would be using a system that has a
serdev driver (operating @ 1Mbaud+) and trying to do a X/YMODEM
transfer via serial console at comparable baudrates.
To at least partially ameliorate the problem, add code that will
expose "polling_interval" as a parameter, so that the user would have
an option of temporarily disabling (or significatly decreasing the
rate) of a given serdev's polling.
Signed-off-by: Andrey Smirnov <andrew.smirnov@xxxxxxxxx>
---
common/serdev.c | 26 +++++++++++++++++++++++++-
1 file changed, 25 insertions(+), 1 deletion(-)
diff --git a/common/serdev.c b/common/serdev.c
index 50eadc804..4a6dbefe6 100644
--- a/common/serdev.c
+++ b/common/serdev.c
@@ -34,12 +34,26 @@ static void serdev_device_poller(void *context)
serdev->polling_interval,
serdev_device_poller,
serdev);
+ } else {
+ poller_async_cancel(&serdev->poller);
}
}
+static int serdev_device_set_polling_interval(struct param_d *param, void *serdev)
+{
+ /*
+ * We execute poller ever time polling_interval changes to get
+ * any unprocessed immediate Rx data as well as to propagate
+ * polling_interval chagnes to outstanging async pollers.
+ */
+ serdev_device_poller(serdev);
+ return 0;
+}
+
int serdev_device_open(struct serdev_device *serdev)
{
struct console_device *cdev = to_console_device(serdev);
+ struct param_d *p;
int ret;
if (!cdev->putc || !cdev->getc)
@@ -57,7 +71,17 @@ int serdev_device_open(struct serdev_device *serdev)
if (ret)
return ret;
- return console_open(cdev);
+ ret = console_open(cdev);
+ if (ret)
+ return ret;
+
+ p = dev_add_param_uint64(serdev->dev, "polling_interval",
+ serdev_device_set_polling_interval, NULL,
+ &serdev->polling_interval, "%llu", serdev);
+ if (IS_ERR(p))
+ return PTR_ERR(p);
+
+ return 0;
}
unsigned int serdev_device_set_baudrate(struct serdev_device *serdev,
--
2.14.3
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