Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756891AbZLNR7M (ORCPT ); Mon, 14 Dec 2009 12:59:12 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753110AbZLNR7L (ORCPT ); Mon, 14 Dec 2009 12:59:11 -0500 Received: from mail-ew0-f219.google.com ([209.85.219.219]:59112 "EHLO mail-ew0-f219.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751739AbZLNR7E (ORCPT ); Mon, 14 Dec 2009 12:59:04 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=ZWTai11ssiYrzEy8OH6OwjxGAEaA0nEZ8VKmETGHwBinbADTWSVbICHRO3jXyWw6CG rBfM5RN6cTUGl14s1pC86wtKuibJ1HxOYzeAUADpcMp8tzhbO2ONa+COLkmxns6YJFPP zgH/2YdaO3NGsVzBoMuMlT2GlHScNYQehIM4w= Subject: Re: [PATCH 1/4] mfd: mc13783: Take care of semantic inversion between read and write value of two bits in POWER_MISCELLANEUS register. From: Alberto Panizzo To: Sergei Shtylyov Cc: Uwe =?ISO-8859-1?Q?Kleine-K=F6nig?= , Samuel Ortiz , Sascha linux-arm , Mark Brown , linux-kernel , linux-arm-kernel-infradead , Liam Girdwood In-Reply-To: <4B26799F.1020507@ru.mvista.com> References: <1260808880.2022.98.camel@climbing-alby> <1260810776.2022.130.camel@climbing-alby> <4B26799F.1020507@ru.mvista.com> Content-Type: text/plain; charset="UTF-8" Date: Mon, 14 Dec 2009 18:59:00 +0100 Message-ID: <1260813540.2022.174.camel@climbing-alby> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3113 Lines: 81 Il giorno lun, 14/12/2009 alle 20.45 +0300, Sergei Shtylyov ha scritto: > > + if (offset == MC13783_REG_POWER_MISCELLANEOUS) > > + buf &= !(MC13783_REGCTRL_PWGT1SPIEN | > > > > Are you sure ! shouldn't be ~ here? > > > + MC13783_REGCTRL_PWGT2SPIEN); > > > > !(MC13783_REGCTRL_PWGT1SPIEN | MC13783_REGCTRL_PWGT2SPIEN) would > evaluate to 0 which is most probably not what you want. > > WBR, Sergei For sure, you are right. The correct patch below.. PWGT1DRV and PWGT1DRV are two digital output controlled by two corresponding hardware signals (Pin PWGTnEN) that are meant to be used to control core power supplies. The register MC13783_REG_POWER_MISCELLANEOUS contain the two control and status bit (PWGTnSPIEN) where write and read meaning is summarised by the following table: Bit PWGTxSPIEN | Pin PWGTxEN | PWGTxDRV | Read Back 0 = default | | | PWGTxSPIEN ---------------+-------------+----------+------------ 1 | x | Low | 0 0 | 0 | High | 1 0 | 1 | Low | 0 Writing a 1 to those bits will turn off the corresponding core power supply. As there is no way to read back the value of PWGTnSPIEN, the behaviour chosen is to let always the hardware control itself leaving those bits at the default value. This patch is especially needed for manipulate the other bits in the same register, where the read-modify-write operation can produce unwanted power fault. Signed-off-by: Alberto Panizzo --- drivers/mfd/mc13783-core.c | 10 ++++++++++ 1 files changed, 10 insertions(+), 0 deletions(-) diff --git a/drivers/mfd/mc13783-core.c b/drivers/mfd/mc13783-core.c index a1ade23..3953297 100644 --- a/drivers/mfd/mc13783-core.c +++ b/drivers/mfd/mc13783-core.c @@ -171,6 +171,9 @@ int mc13783_reg_read(struct mc13783 *mc13783, unsigned int offset, u32 *val) } EXPORT_SYMBOL(mc13783_reg_read); +#define MC13783_REG_POWER_MISCELLANEOUS 34 +#define MC13783_REGCTRL_PWGT1SPIEN (1 << 15) +#define MC13783_REGCTRL_PWGT2SPIEN (1 << 16) int mc13783_reg_write(struct mc13783 *mc13783, unsigned int offset, u32 val) { u32 buf; @@ -187,6 +190,13 @@ int mc13783_reg_write(struct mc13783 *mc13783, unsigned int offset, u32 val) buf = 1 << 31 | offset << MC13783_REGOFFSET_SHIFT | val; + /* Take care of table 4-24 in Freescale MC13783IGPLDRM.pdf making + * the assumption that PWGTnDRV signals controls core power supplies + * that software must not disable. */ + if (offset == MC13783_REG_POWER_MISCELLANEOUS) + buf &= ~(MC13783_REGCTRL_PWGT1SPIEN | + MC13783_REGCTRL_PWGT2SPIEN); + memset(&t, 0, sizeof(t)); t.tx_buf = &buf; -- 1.6.3.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/