From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755734Ab3FDRhf (ORCPT ); Tue, 4 Jun 2013 13:37:35 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:42405 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753284Ab3FDRhd (ORCPT ); Tue, 4 Jun 2013 13:37:33 -0400 From: Grygorii Strashko To: Wolfram Sang CC: Grygorii Strashko , , , Subject: [PATCH] i2c: Let users disable "Probe an I2C bus for certain devices" Date: Tue, 4 Jun 2013 20:33:42 +0300 Message-ID: <1370367222-19353-1-git-send-email-grygorii.strashko@ti.com> X-Mailer: git-send-email 1.7.9.5 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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