From: Clara Kowalsky <clara.kowalsky@siemens.com>
To: xenomai@lists.linux.dev
Cc: jan.kiszka@siemens.com, florian.bezdeka@siemens.com,
Clara Kowalsky <clara.kowalsky@siemens.com>
Subject: [PATCH 5/5] driver/gpio: Take timestamp according to used clock
Date: Tue, 16 Apr 2024 10:59:11 +0200 [thread overview]
Message-ID: <20240416085911.62073-6-clara.kowalsky@siemens.com> (raw)
In-Reply-To: <20240416085911.62073-1-clara.kowalsky@siemens.com>
The log of the loopback device shows that there are problems in the
clock reading and therefore in the diff calculation of the timestamps:
----rt task, gpio loop, test run----
index: 0, inner_diff: 12, outer_diff: 25
index: 1, inner_diff: 18446744073699568, outer_diff: 9
index: 2, inner_diff: 5, outer_diff: 13
index: 3, inner_diff: 18446744073699543, outer_diff: 8
index: 4, inner_diff: 4, outer_diff: 12
index: 5, inner_diff: 18446744073699553, outer_diff: 8
Inner_diff, the difference between gpio_write (write time) and
rdo.timestamp (read time), should always be positive. However, as the
selected clock (monotonic or realtime) is not correctly used for
determining rdo.timestamp, the case occurs that rdo.timestamp is smaller
than gpio_write, resulting in a negative difference and in an overflow.
To fix this, the rdo.timestamp is correctly read from selected clock,
either monotonic or realtime clock.
Signed-off-by: Clara Kowalsky <clara.kowalsky@siemens.com>
---
kernel/drivers/gpio/gpio-core.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/drivers/gpio/gpio-core.c b/kernel/drivers/gpio/gpio-core.c
index e41c64050..8ab9ae43e 100644
--- a/kernel/drivers/gpio/gpio-core.c
+++ b/kernel/drivers/gpio/gpio-core.c
@@ -233,8 +233,9 @@ static ssize_t gpio_pin_read_rt(struct rtdm_fd *fd,
ret = rtdm_event_wait(&pin->event);
if (ret)
return ret;
- rdo.timestamp = pin->timestamp;
- } else if (pin->monotonic_timestamp) {
+ }
+
+ if (pin->monotonic_timestamp) {
rdo.timestamp = rtdm_clock_read_monotonic();
} else {
rdo.timestamp = rtdm_clock_read();
--
2.39.2
next prev parent reply other threads:[~2024-04-16 9:00 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-16 8:59 [PATCH 0/5] I/O benchmark fixes Clara Kowalsky
2024-04-16 8:59 ` [PATCH 1/5] drivers/gpio: Add driver for BCM2711-based SoCs Clara Kowalsky
2024-05-21 16:48 ` Jan Kiszka
2024-04-16 8:59 ` [PATCH 2/5] testsuite/gpiobench: Toggle output pin in react mode Clara Kowalsky
2024-05-21 16:48 ` Jan Kiszka
2024-06-07 13:40 ` Kowalsky, Clara
2024-04-16 8:59 ` [PATCH 3/5] testsuite/gpiobench: Synchronize index of loopback mode and " Clara Kowalsky
2024-05-21 16:48 ` Jan Kiszka
2024-04-16 8:59 ` [PATCH 4/5] testsuite/gpiobench: Fix calculation of maximum latency Clara Kowalsky
2024-05-21 16:49 ` Jan Kiszka
2024-04-16 8:59 ` Clara Kowalsky [this message]
2024-05-21 17:00 ` [PATCH 5/5] driver/gpio: Take timestamp according to used clock Jan Kiszka
2024-06-07 13:41 ` Kowalsky, Clara
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