From: Grygorii Strashko <grygorii.strashko@ti.com>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: Grygorii Strashko <grygorii.strashko@ti.com>,
<linux-i2c@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linux-omap@vger.kernel.org>
Subject: [PATCH] i2c: Let users disable "Probe an I2C bus for certain devices"
Date: Tue, 4 Jun 2013 20:33:42 +0300 [thread overview]
Message-ID: <1370367222-19353-1-git-send-email-grygorii.strashko@ti.com> (raw)
Currently the I2C devices instantiation Method 3 "Probe an I2C bus for
certain devices" (see Documentation/i2c/instantiating-devices) is always
enabled for all platforms (boards) and can't be disabled.
This feature introduces a system boot time delay for boards,
where I2C devices topology is explicitly defined in DT or platform code
(Method 1 and Method 2 are used only) and especially when i2c-gpio is used.
For example:
When CONFIG_SENSORS_LM75 option was enabled for omap4-sdp board -
it introduces 5-6 ms boot delay.
When CONFIG_SENSORS_LM75 option was enabled for omap5-uevm board,
where i2c-gpio is used for HDMI edid reading - it introduces up to 5 sec boot
delay.
Hence, introduce CONFIG_I2C_DISABLE_DEVICE_DETECTION configuration option
to allow disabling of I2C devices instantiation Method 3 "Probe an I2C bus
for certain devices" if it's not needed (usually for embedded systems).
CC: linux-i2c@vger.kernel.org
CC: linux-kernel@vger.kernel.org
CC: linux-omap@vger.kernel.org
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
---
drivers/i2c/Kconfig | 10 ++++++++++
drivers/i2c/i2c-core.c | 6 ++++++
2 files changed, 16 insertions(+)
diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index e380c6e..f7b220b 100644
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -124,4 +124,14 @@ config I2C_DEBUG_BUS
a problem with I2C support and want to see more of what is going
on.
+config I2C_DISABLE_DEVICE_DETECTION
+ bool "I2C Disable device detection"
+ default n
+ help
+ Say Y here, if you have explicitly defined I2C device topology in DT
+ or platform code and don't need to detect presence of supported I2C
+ devices automatically (Documentation/i2c/instantiating-devices -
+ Method 1 and Method 2 are used only). Enabling this option allows to
+ reduce system boot time, especially in case when i2c-gpio driver is used.
+
endif # I2C
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 48e31ed..d5ab7a3 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -54,7 +54,9 @@ static DEFINE_MUTEX(core_lock);
static DEFINE_IDR(i2c_adapter_idr);
static struct device_type i2c_client_type;
+#ifndef CONFIG_I2C_DISABLE_DEVICE_DETECTION
static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
+#endif
/* ------------------------------------------------------------------------- */
@@ -958,7 +960,9 @@ static int i2c_do_add_adapter(struct i2c_driver *driver,
struct i2c_adapter *adap)
{
/* Detect supported devices on that bus, and instantiate them */
+#ifndef CONFIG_I2C_DISABLE_DEVICE_DETECTION
i2c_detect(adap, driver);
+#endif
/* Let legacy drivers scan this bus for matching devices */
if (driver->attach_adapter) {
@@ -1672,6 +1676,7 @@ static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr)
return err >= 0;
}
+#ifndef CONFIG_I2C_DISABLE_DEVICE_DETECTION
static int i2c_detect_address(struct i2c_client *temp_client,
struct i2c_driver *driver)
{
@@ -1760,6 +1765,7 @@ static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
kfree(temp_client);
return err;
}
+#endif
int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr)
{
--
1.7.9.5
next reply other threads:[~2013-06-04 17:37 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-04 17:33 Grygorii Strashko [this message]
2013-06-04 17:49 ` [PATCH] i2c: Let users disable "Probe an I2C bus for certain devices" Wolfram Sang
2013-06-05 16:13 ` Grygorii Strashko
2013-06-07 9:06 ` Wolfram Sang
2013-06-07 9:09 ` [RFC] i2c: add deprecation warning for class based instantiation Wolfram Sang
2013-06-19 10:15 ` Wolfram Sang
2013-06-19 18:21 ` Grygorii Strashko
2013-06-20 18:37 ` Wolfram Sang
2013-06-19 18:22 ` Grygorii Strashko
2013-06-19 18:22 ` [RFC 1/2] i2c: omap: drop class based instantiation of slaves Grygorii Strashko
2013-06-19 18:22 ` [RFC 2/2] i2c: gpio: " Grygorii Strashko
2013-06-07 10:10 ` [PATCH] i2c: Let users disable "Probe an I2C bus for certain devices" Grygorii Strashko
2013-06-07 21:28 ` Wolfram Sang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1370367222-19353-1-git-send-email-grygorii.strashko@ti.com \
--to=grygorii.strashko@ti.com \
--cc=linux-i2c@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-omap@vger.kernel.org \
--cc=wsa@the-dreams.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).