From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751174AbcFSNQZ (ORCPT ); Sun, 19 Jun 2016 09:16:25 -0400 Received: from down.free-electrons.com ([37.187.137.238]:57011 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750720AbcFSNQY convert rfc822-to-8bit (ORCPT ); Sun, 19 Jun 2016 09:16:24 -0400 Date: Sun, 19 Jun 2016 15:16:19 +0200 From: Boris Brezillon To: icenowy@aosc.xyz Cc: "maxime.ripard@free-electrons.com" , "wens@csie.org" , "robh+dt@kernel.org" , "richard@nod.at" , "dwmw2@infradead.org" , "computersforpeace@gmail.com" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-mtd@lists.infradead.org" , "linux-sunxi@googlegroups.com" , Philipp Zabel Subject: Re: [PATCH 2/2] mtd: nand: sunxi: add reset line support Message-ID: <20160619151619.4edc64f6@bbrezillon> In-Reply-To: <2748041466341860@web7m.yandex.ru> References: <20160619113739.30362-1-icenowy@aosc.xyz> <20160619113739.30362-2-icenowy@aosc.xyz> <20160619140652.07ab03c9@bbrezillon> <2686901466340069@web27g.yandex.ru> <20160619145303.0bdf59ea@bbrezillon> <2748041466341860@web7m.yandex.ru> Organization: Free Electrons X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 19 Jun 2016 21:11:00 +0800 icenowy@aosc.xyz wrote: > Then I will soon make the v2 patch set, with the error detection part fixed. > > But why does sunxi-mmc check only EPROBE_DEFER? I guess someone had a probe-dependency problem and fixed this case but ignored all the possible errors. But there may be other reasons for devm_reset_control_get_optional() to fail. The only one that is really reflecting that the reset line is not defined in the DT is -ENOENT. > > 19.06.2016, 20:53, "Boris Brezillon" : > > On Sun, 19 Jun 2016 20:41:09 +0800 > > icenowy@aosc.xyz wrote: > > > >>  To be honest, I copied them from sunxi-mmc.c. > >> > >>  What function should be chosen better? > > > > You did the right thing (except for the error detection part). My > > question was addressed to Philipp (the reset subsystem maintainer). > > > >>  19.06.2016, 20:06, "Boris Brezillon" : > >>  > +Philipp > >>  > > >>  > On Sun, 19 Jun 2016 19:37:39 +0800 > >>  > Icenowy Zheng wrote: > >>  > > >>  >>  The NAND controller on some sun8i chips needs its reset line to be deasserted > >>  >>  before they can enter working state. This commit added the reset line process > >>  >>  to the driver. > >>  >> > >>  >>  Signed-off-by: Icenowy Zheng > >>  >>  --- > >>  >>   drivers/mtd/nand/sunxi_nand.c | 14 ++++++++++++++ > >>  >>   1 file changed, 14 insertions(+) > >>  >> > >>  >>  diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c > >>  >>  index a83a690..1502748 100644 > >>  >>  --- a/drivers/mtd/nand/sunxi_nand.c > >>  >>  +++ b/drivers/mtd/nand/sunxi_nand.c > >>  >>  @@ -39,6 +39,7 @@ > >>  >>   #include > >>  >>   #include > >>  >>   #include > >>  >>  +#include > >>  >> > >>  >>   #define NFC_REG_CTL 0x0000 > >>  >>   #define NFC_REG_ST 0x0004 > >>  >>  @@ -269,6 +270,7 @@ struct sunxi_nfc { > >>  >>           void __iomem *regs; > >>  >>           struct clk *ahb_clk; > >>  >>           struct clk *mod_clk; > >>  >>  + struct reset_control *reset; > >>  >>           unsigned long assigned_cs; > >>  >>           unsigned long clk_rate; > >>  >>           struct list_head chips; > >>  >>  @@ -1871,6 +1873,18 @@ static int sunxi_nfc_probe(struct platform_device *pdev) > >>  >>           if (ret) > >>  >>                   goto out_ahb_clk_unprepare; > >>  >> > >>  >>  + nfc->reset = devm_reset_control_get_optional(dev, "ahb"); > >>  >>  + if (PTR_ERR(nfc->reset) == -EPROBE_DEFER) > >>  >>  + return PTR_ERR(nfc->reset); > >>  > > >>  > Actually you should test for != -ENOENT, because all error codes except > >>  > this one should stop the ->probe(). > >>  > > >>  > BTW, this devm_reset_control_get_optional() is really weird. While most > >>  > _optional() methods return NULL when the element is not defined in the > >>  > DT, this one returns -ENOTENT, which makes it impossible to > >>  > differentiate a real error from a undefined reset line (which is a > >>  > valid case for _optional()). > >>  > > >>  > Philipp, is there a good reason for doing that? > >>  > > >>  >>  + > >>  >>  + if (!IS_ERR(nfc->reset)) { > >>  >>  + ret = reset_control_deassert(nfc->reset); > >>  >>  + if (ret) { > >>  >>  + dev_err(dev, "reset err %d\n", ret); > >>  >>  + goto out_mod_clk_unprepare; > >>  >>  + } > >>  >>  + } > >>  >>  +