From: Nicholas Mc Guire <hofrat@opentech.at>
To: Sakari Ailus <sakari.ailus@iki.fi>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>,
linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
Nicholas Mc Guire <hofrat@opentech.at>
Subject: [PATCH 1/3] media: smiapp: core: add range to usleep_range
Date: Sun, 7 Apr 2019 04:16:02 +0200 [thread overview]
Message-ID: <1554603364-10500-1-git-send-email-hofrat@opentech.at> (raw)
Allow the hrtimer subsystem to coalesce delay timers of lower accuracy
by providing a suitable range
Signed-off-by: Nicholas Mc Guire <hofrat@opentech.at>
---
Problem located by an experimental coccinelle script
hrtimers in atomic context have limited accuracy due to possible
context-switching and interruption so the accuracy is limited
anyway. Giving the hrtimer subsystem a reasonable range for merging
hrtimers helps to reduce the load on the hrtimer subsystem. As this
delays do not seem to mandate high accuracy the range of a factor
two seems acceptable.
Patch was compile tested with: x86_64_defconfig + MEDIA_SUPPORT=m,
MEDIA_CAMERA_SUPPORT=y, MEDIA_CONTROLLER=y, VIDEO_V4L2_SUBDEV_API=y,
VIDEO_SMIAPP=m
(with a number of sparse warnings on sizeof() usage)
Patch is against 5.1-rc3 (localversion-next is next-20190405)
drivers/media/i2c/smiapp/smiapp-core.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/media/i2c/smiapp/smiapp-core.c b/drivers/media/i2c/smiapp/smiapp-core.c
index 58a45c3..c0c29ec 100644
--- a/drivers/media/i2c/smiapp/smiapp-core.c
+++ b/drivers/media/i2c/smiapp/smiapp-core.c
@@ -1222,19 +1222,19 @@ static int smiapp_power_on(struct device *dev)
dev_err(&client->dev, "failed to enable vana regulator\n");
return rval;
}
- usleep_range(1000, 1000);
+ usleep_range(1000, 2000);
rval = clk_prepare_enable(sensor->ext_clk);
if (rval < 0) {
dev_dbg(&client->dev, "failed to enable xclk\n");
goto out_xclk_fail;
}
- usleep_range(1000, 1000);
+ usleep_range(1000, 2000);
gpiod_set_value(sensor->xshutdown, 1);
sleep = SMIAPP_RESET_DELAY(sensor->hwcfg->ext_clk);
- usleep_range(sleep, sleep);
+ usleep_range(sleep, sleep*2);
mutex_lock(&sensor->mutex);
@@ -1381,7 +1381,7 @@ static int smiapp_power_off(struct device *dev)
gpiod_set_value(sensor->xshutdown, 0);
clk_disable_unprepare(sensor->ext_clk);
- usleep_range(5000, 5000);
+ usleep_range(5000, 10000);
regulator_disable(sensor->vana);
sensor->streaming = false;
--
2.1.4
next reply other threads:[~2019-04-07 3:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-07 2:16 Nicholas Mc Guire [this message]
2019-04-07 2:16 ` [PATCH 2/3] media: smiapp: regs: add range to usleep_range Nicholas Mc Guire
2019-04-07 2:16 ` [PATCH 3/3] media: smiapp: quirk: " Nicholas Mc Guire
2019-04-30 13:49 ` [PATCH 1/3] media: smiapp: core: " Sakari Ailus
2019-05-04 9:46 ` Nicholas Mc Guire
2019-05-07 21:04 ` Sakari Ailus
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