From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 26E1DC433DB for ; Tue, 16 Mar 2021 07:22:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DE0F264FBD for ; Tue, 16 Mar 2021 07:22:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232323AbhCPHWS (ORCPT ); Tue, 16 Mar 2021 03:22:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43964 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229952AbhCPHVr (ORCPT ); Tue, 16 Mar 2021 03:21:47 -0400 Received: from mail-wm1-x32a.google.com (mail-wm1-x32a.google.com [IPv6:2a00:1450:4864:20::32a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 629DFC061756 for ; Tue, 16 Mar 2021 00:21:47 -0700 (PDT) Received: by mail-wm1-x32a.google.com with SMTP id w203-20020a1c49d40000b029010c706d0642so3324035wma.0 for ; Tue, 16 Mar 2021 00:21:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=3PC4L/ElKOxjRdktmch4SpZkUtmQpCd/z4zTr/LSIf0=; b=dmH4uVYmL9aJZFOiQxa1fPH8t4BIGG879xw4oi2VAdngKyAF4rV8HldmACFGuWZrTz Ok6tcbNiiEANHgyYotM2KoASgWrtFjhlc+InLx/v93IwDNZhRP3Ru2gVC7hNhG58A/Ah peB46rKLF0udJrXH56zJrU16OqFtYDi4awYmDAt6VfJdgf00n+Jkyz77OsIi29QGdn3S ofzfNuHXwIo1jNxqytt8nNs2HlejZJK4DuwVCNNH6lVm/5BqpqSDLY+qZFNKd+1Ail7X yXVy9uGmrXyy8n8KbamcpEJjkN0xnniPc2VHwsRpWsUgUCoa4hJKA3ytpd00kq6Ts3RW NjVg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=3PC4L/ElKOxjRdktmch4SpZkUtmQpCd/z4zTr/LSIf0=; b=E7skTRvWvfySNsYF9/E9LSp+UCJQ820xJeUQGCo6DNL5B0GV6U0bUd2dwe4xg5Cs2r WKLyABLUTd9R1cENKyF07oGBzkxO/beKE72i36U7HxT5pnK/5TnQFzdX3iuw3LCsoBRh 8zHNL2jpSHAZYrmww+j+EYkm3WovrFUQo1B4sfX2Ui5Xf/RzLqoOujm/xlTb5nXhkf9S DdfU5US36j7I37NpMvMRByOTTD35Ay7hJO0nJ1XUfFDT/x/7I/j/3t29je/Z6cHlaBIp /chaQAnMsAd+y7NhAEXXcr0Ltwm1Jk8kgRkQnjts1FxArFX8AdOirY/lSFAqNZIrRnCg a63A== X-Gm-Message-State: AOAM531PwTTzoagTRCBo807/LLiOswpUIeWKzxWlVQDgxhOFSFMDvDEo dy0veJFwU9dGVpEM59kz1P+A/Q== X-Google-Smtp-Source: ABdhPJz5cQmfQ4Ehxs4LnAG/W0t/jtMCZLitLYsh7qfZESNmRG8HctRVeDDGKCMarxLEo3bvJfb6cA== X-Received: by 2002:a05:600c:290a:: with SMTP id i10mr3240122wmd.91.1615879306045; Tue, 16 Mar 2021 00:21:46 -0700 (PDT) Received: from dell ([91.110.221.243]) by smtp.gmail.com with ESMTPSA id t8sm20888097wrr.10.2021.03.16.00.21.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 16 Mar 2021 00:21:45 -0700 (PDT) Date: Tue, 16 Mar 2021 07:21:43 +0000 From: Lee Jones To: Mark Jonas Cc: Support Opensource , linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org, Adam.Thomson.Opensource@diasemi.com, stwiss.opensource@diasemi.com, marek.vasut@gmail.com, tingquan.ruan@cn.bosch.com, hubert.streidl@de.bosch.com, Wolfram Sang Subject: Re: [PATCH v5] mfd: da9063: Support SMBus and I2C mode Message-ID: <20210316072143.GA701493@dell> References: <20210315160903.799426-1-mark.jonas@de.bosch.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210315160903.799426-1-mark.jonas@de.bosch.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 15 Mar 2021, Mark Jonas wrote: > From: Hubert Streidl > > By default the PMIC DA9063 2-wire interface is SMBus compliant. This > means the PMIC will automatically reset the interface when the clock > signal ceases for more than the SMBus timeout of 35 ms. > > If the I2C driver / device is not capable of creating atomic I2C > transactions, a context change can cause a ceasing of the clock signal. > This can happen if for example a real-time thread is scheduled. Then > the DA9063 in SMBus mode will reset the 2-wire interface. Subsequently > a write message could end up in the wrong register. This could cause > unpredictable system behavior. > > The DA9063 PMIC also supports an I2C compliant mode for the 2-wire > interface. This mode does not reset the interface when the clock > signal ceases. Thus the problem depicted above does not occur. > > This patch tests for the bus functionality "I2C_FUNC_I2C". It can > reasonably be assumed that the bus cannot obey SMBus timings if > this functionality is set. SMBus commands most probably are emulated > in this case which is prone to the latency issue described above. > > This patch enables the I2C bus mode if I2C_FUNC_I2C is set or > otherwise keeps the default SMBus mode. > > Signed-off-by: Hubert Streidl > Signed-off-by: Mark Jonas > --- > drivers/mfd/da9063-i2c.c | 10 ++++++++++ > include/linux/mfd/da9063/registers.h | 3 +++ > 2 files changed, 13 insertions(+) Code looks good to me now, thanks. However, this doesn't look like it would pass checkpatch. Have you tried to build with W=1 and checkpatch? > diff --git a/drivers/mfd/da9063-i2c.c b/drivers/mfd/da9063-i2c.c > index 3781d0bb7786..e8a022e697c5 100644 > --- a/drivers/mfd/da9063-i2c.c > +++ b/drivers/mfd/da9063-i2c.c > @@ -442,6 +442,16 @@ static int da9063_i2c_probe(struct i2c_client *i2c, > return ret; > } > > + /* If SMBus is not available and only I2C is possible, enter I2C mode */ > + if (i2c_check_functionality(i2c->adapter, I2C_FUNC_I2C)) { > + ret = regmap_clear_bits(da9063->regmap, DA9063_REG_CONFIG_J, > + DA9063_TWOWIRE_TO); > + if (ret < 0) { > + dev_err(da9063->dev, "Failed to set Two-Wire Bus Mode.\n"); > + return -EIO; > + } > + } > + > return da9063_device_init(da9063, i2c->irq); > } > > diff --git a/include/linux/mfd/da9063/registers.h b/include/linux/mfd/da9063/registers.h > index 1dbabf1b3cb8..6e0f66a2e727 100644 > --- a/include/linux/mfd/da9063/registers.h > +++ b/include/linux/mfd/da9063/registers.h > @@ -1037,6 +1037,9 @@ > #define DA9063_NONKEY_PIN_AUTODOWN 0x02 > #define DA9063_NONKEY_PIN_AUTOFLPRT 0x03 > > +/* DA9063_REG_CONFIG_J (addr=0x10F) */ > +#define DA9063_TWOWIRE_TO 0x40 > + > /* DA9063_REG_MON_REG_5 (addr=0x116) */ > #define DA9063_MON_A8_IDX_MASK 0x07 > #define DA9063_MON_A8_IDX_NONE 0x00 -- Lee Jones [李琼斯] Senior Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog