From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752145AbcAEHni (ORCPT ); Tue, 5 Jan 2016 02:43:38 -0500 Received: from regular1.263xmail.com ([211.150.99.132]:35624 "EHLO regular1.263xmail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751978AbcAEHnE (ORCPT ); Tue, 5 Jan 2016 02:43:04 -0500 X-Greylist: delayed 16831 seconds by postgrey-1.27 at vger.kernel.org; Tue, 05 Jan 2016 02:43:01 EST X-263anti-spam: KSV:0; X-MAIL-GRAY: 0 X-MAIL-DELIVERY: 1 X-KSVirus-check: 0 X-ABS-CHECKED: 4 X-ADDR-CHECKED: 0 X-RL-SENDER: jay.xu@rock-chips.com X-FST-TO: linux-kernel@vger.kernel.org X-SENDER-IP: 58.22.7.114 X-LOGIN-NAME: jay.xu@rock-chips.com X-UNIQUE-TAG: X-ATTACHMENT-NUM: 0 X-DNS-TYPE: 0 Subject: Re: [PATCH] i2c: rk3x: init module as subsys call To: Heiko Stuebner References: <1451962938-17398-1-git-send-email-jay.xu@rock-chips.com> <2513923.8oltbpbAin@phil> Cc: wsa@the-dreams.de, wdc@rock-chips.com, huangtao@rock-chips.com, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org From: Jianqun Xu Message-ID: <568B73FF.9090508@rock-chips.com> Date: Tue, 5 Jan 2016 15:42:55 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 MIME-Version: 1.0 In-Reply-To: <2513923.8oltbpbAin@phil> Content-Type: text/plain; charset=gbk; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Heiko: ÔÚ 05/01/2016 15:02, Heiko Stuebner дµÀ: > Hi Jianqun, > > Am Dienstag, 5. Januar 2016, 11:02:18 schrieb jianqun.xu: >> From: Xu Jianqun >> >> There is a requirement from pmic device, which is on the i2c bus, >> that the pmic needs to be called earlier then devices powered by >> the outputs of the pmic, if not, the devices maybe fail to probe. >> >> For example, a pmic on i2c0, and touchscreen device on i2c2, >> i2c0: - pmic(rk818) >> i2c2: - ts(gt911), powered by rk818 on i2c0 >> >> The problem will happen if the i2c2 node in dts file is ordered >> before i2c0 node, then ts(gt911) will be probed before pmic(rk818), >> since the power from the pmic(rk818) for ts(gt911) hasn't enabled, >> so ts(gt911) will fail to probe due to the failure of i2c test. >> >> But if we set the i2c0 node before i2c2, there is no this issue. >> >> The stable way to make sure that pmic can be intalized before other >> peripher devices is to make the pmic module be subsys call, the i2c >> module need to be subsys call firstly. > > I do believe that came up in the past already and the direction from then > was (and most likely still is) that drivers should make use of the probe- > deferral mechanism instead of wiggling with the initcall ordering. > > Your touchscreen will have a "xyz-supply" property and I think the > regulator-framework should already emit a -EPROBE_DEFER at regulator_get, > when the regulator is specified but not available yet. > It seems more reasonable, thanks for advice, I will have a try. > > Heiko > >> >> Signed-off-by: Xu Jianqun >> --- >> drivers/i2c/busses/i2c-rk3x.c | 12 +++++++++++- >> 1 file changed, 11 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c >> index c1935eb..00e5959 100644 >> --- a/drivers/i2c/busses/i2c-rk3x.c >> +++ b/drivers/i2c/busses/i2c-rk3x.c >> @@ -1037,7 +1037,17 @@ static struct platform_driver rk3x_i2c_driver = { >> }, >> }; >> >> -module_platform_driver(rk3x_i2c_driver); >> +static int __init rk3x_i2c_init(void) >> +{ >> + return platform_driver_register(&rk3x_i2c_driver); >> +} >> +subsys_initcall(rk3x_i2c_init); >> + >> +static void __exit rk3x_i2c_exit(void) >> +{ >> + platform_driver_unregister(&rk3x_i2c_driver); >> +} >> +module_exit(rk3x_i2c_exit); >> >> MODULE_DESCRIPTION("Rockchip RK3xxx I2C Bus driver"); >> MODULE_AUTHOR("Max Schwarz "); > > > >