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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3079CC433EF for ; Thu, 17 Feb 2022 23:47:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229597AbiBQXrd (ORCPT ); Thu, 17 Feb 2022 18:47:33 -0500 Received: from gmail-smtp-in.l.google.com ([23.128.96.19]:55920 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229473AbiBQXrb (ORCPT ); Thu, 17 Feb 2022 18:47:31 -0500 Received: from thorn.bewilderbeest.net (thorn.bewilderbeest.net [IPv6:2605:2700:0:5::4713:9cab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5CB0B378F5A; Thu, 17 Feb 2022 15:47:04 -0800 (PST) Received: from hatter.bewilderbeest.net (174-21-187-98.tukw.qwest.net [174.21.187.98]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: zev) by thorn.bewilderbeest.net (Postfix) with ESMTPSA id E7DFF135; Thu, 17 Feb 2022 15:37:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bewilderbeest.net; s=thorn; t=1645141061; bh=vR4wXeIsXpO2AhBfg332ghYS2clWTWkcLNBwoNM5S2w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UwM3xDxYKJYkwEYh3RtBbQE2Eu79t1a2jQOUNlsVvXmE/G5vPk9pBGt9jFV51PG7R QrrgrFIzDLevsMP352cJ7xc1wGPWIpEX6CPwAEWN8jBUoMb/kymUkzqctzyiLhXoxG rrjAV1utG/aYOEThHP+APsipOU0RcHg+C9cIDQiY= Date: Thu, 17 Feb 2022 15:37:39 -0800 From: Zev Weiss To: Guenter Roeck Cc: Jean Delvare , linux-hwmon@vger.kernel.org, openbmc@lists.ozlabs.org, Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Mark Brown , Liam Girdwood Subject: Re: [PATCH 1/4] hwmon: (pmbus) Add get_error_flags support to regulator ops Message-ID: References: <20220217104444.7695-1-zev@bewilderbeest.net> <20220217104444.7695-2-zev@bewilderbeest.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 17, 2022 at 10:11:32AM PST, Guenter Roeck wrote: >On 2/17/22 02:44, Zev Weiss wrote: >>The various PMBus status bits don't all map perfectly to the more >>limited set of REGULATOR_ERROR_* flags, but there's a reasonable >>number where they correspond well enough. >> >>Signed-off-by: Zev Weiss >>--- >> drivers/hwmon/pmbus/pmbus_core.c | 97 ++++++++++++++++++++++++++++++++ >> 1 file changed, 97 insertions(+) >> >>diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c >>index 776ee2237be2..a274e8e524a5 100644 >>--- a/drivers/hwmon/pmbus/pmbus_core.c >>+++ b/drivers/hwmon/pmbus/pmbus_core.c >>@@ -2417,10 +2417,107 @@ static int pmbus_regulator_disable(struct regulator_dev *rdev) >> return _pmbus_regulator_on_off(rdev, 0); >> } >>+/* A PMBus status flag and the corresponding REGULATOR_ERROR_* flag */ >>+struct pmbus_regulator_status_assoc { >>+ int pflag, rflag; >>+}; >>+ >>+/* PMBus->regulator bit mappings for a PMBus status register */ >>+struct pmbus_regulator_status_category { >>+ int func; >>+ int reg; >>+ const struct pmbus_regulator_status_assoc *bits; /* zero-terminated */ >>+}; >>+ >>+static const struct pmbus_regulator_status_category pmbus_regulator_flag_map[] = { >>+ { >>+ .func = PMBUS_HAVE_STATUS_VOUT, >>+ .reg = PMBUS_STATUS_VOUT, >>+ .bits = (const struct pmbus_regulator_status_assoc[]) { >>+ { PB_VOLTAGE_UV_WARNING, REGULATOR_ERROR_UNDER_VOLTAGE_WARN }, >>+ { PB_VOLTAGE_UV_FAULT, REGULATOR_ERROR_UNDER_VOLTAGE }, >>+ { PB_VOLTAGE_OV_WARNING, REGULATOR_ERROR_OVER_VOLTAGE_WARN }, >>+ { PB_VOLTAGE_OV_FAULT, REGULATOR_ERROR_REGULATION_OUT }, >>+ { }, >>+ }, >>+ }, { >>+ .func = PMBUS_HAVE_STATUS_IOUT, >>+ .reg = PMBUS_STATUS_IOUT, >>+ .bits = (const struct pmbus_regulator_status_assoc[]) { >>+ { PB_IOUT_OC_WARNING, REGULATOR_ERROR_OVER_CURRENT_WARN }, >>+ { PB_IOUT_OC_FAULT, REGULATOR_ERROR_OVER_CURRENT }, >>+ { PB_IOUT_OC_LV_FAULT, REGULATOR_ERROR_OVER_CURRENT }, >>+ { }, >>+ }, >>+ }, { >>+ .func = PMBUS_HAVE_STATUS_TEMP, >>+ .reg = PMBUS_STATUS_TEMPERATURE, >>+ .bits = (const struct pmbus_regulator_status_assoc[]) { >>+ { PB_TEMP_OT_WARNING, REGULATOR_ERROR_OVER_TEMP_WARN }, >>+ { PB_TEMP_OT_FAULT, REGULATOR_ERROR_OVER_TEMP }, >>+ { }, >>+ }, >>+ }, >>+}; >>+ >>+static int pmbus_regulator_get_error_flags(struct regulator_dev *rdev, unsigned int *flags) >>+{ >>+ int i, status, statusreg; >>+ const struct pmbus_regulator_status_category *cat; >>+ const struct pmbus_regulator_status_assoc *bit; >>+ struct device *dev = rdev_get_dev(rdev); >>+ struct i2c_client *client = to_i2c_client(dev->parent); >>+ struct pmbus_data *data = i2c_get_clientdata(client); >>+ u8 page = rdev_get_id(rdev); >>+ int func = data->info->func[page]; >>+ >>+ *flags = 0; >>+ >>+ for (i = 0; i < ARRAY_SIZE(pmbus_regulator_flag_map); i++) { >>+ cat = &pmbus_regulator_flag_map[i]; >>+ if (!(func & cat->func)) >>+ continue; >>+ >>+ status = pmbus_read_byte_data(client, page, cat->reg); >>+ if (status < 0) >>+ return status; >>+ >>+ for (bit = cat->bits; bit->pflag; bit++) { >>+ if (status & bit->pflag) >>+ *flags |= bit->rflag; >>+ } >>+ } >>+ >>+ /* >>+ * Map what bits of STATUS_{WORD,BYTE} we can to REGULATOR_ERROR_* >>+ * bits. Some of the other bits are tempting (especially for cases >>+ * where we don't have the relevant PMBUS_HAVE_STATUS_* >>+ * functionality), but there's an unfortunate ambiguity in that >>+ * they're defined as indicating a fault *or* a warning, so we can't >>+ * easily determine whether to report REGULATOR_ERROR_ or >>+ * REGULATOR_ERROR__WARN. >>+ */ >>+ statusreg = data->has_status_word ? PMBUS_STATUS_WORD : PMBUS_STATUS_BYTE; >>+ status = pmbus_get_status(client, page, statusreg); >>+ > >pmbus_get_status() calls data->read_status if PMBUS_STATUS_WORD is provided >as parameter, and data->read_status is set to pmbus_read_status_byte() >if reading the word status is not supported. Given that, why not just call >pmbus_get_status(client, page, PMBUS_STATUS_WORD) ? Good point, I'll change it to do that instead. (And send v2 separately from the power-efuse driver patches.) > >>+ if (status < 0) >>+ return status; >>+ >>+ if (pmbus_regulator_is_enabled(rdev) && (status & PB_STATUS_OFF)) >>+ *flags |= REGULATOR_ERROR_FAIL; >>+ if (status & PB_STATUS_IOUT_OC) >>+ *flags |= REGULATOR_ERROR_OVER_CURRENT; > >If the current status register is supported, this effectively means that >an overcurrent warning is always reported as both REGULATOR_ERROR_OVER_CURRENT >and REGULATOR_ERROR_OVER_CURRENT_WARN. Is that intentional ? > No, but I don't think (by my reading of the spec) that's what would happen? I'm looking at table 16 ("STATUS_WORD Message Contents") in section 17.2 ("STATUS_WORD") of Part II of revision 1.3.1 of the PMBus spec, which says that bit 4 of the low byte (PB_STATUS_IOUT_OC) indicates an output overcurrent fault, not a warning (in contrast to most of the other bits, which may indicate either). > >>+ if (status & PB_STATUS_VOUT_OV) >>+ *flags |= REGULATOR_ERROR_REGULATION_OUT; > >Same for voltage. Likewise, PB_STATUS_VOUT_OV is specified as indicating a fault, not a warning. >On the other side, temperature limit violations are not >reported at all unless the temperature status register exists. >That seems to be a bit inconsistent to me. > Right -- that's because PB_STATUS_TEMPERATURE is one of the "fault or warning" bits (unlike VOUT_OV and IOUT_OC), and hence it's an ambiguous case as described in the comment before the pmbus_get_status() call. It's certainly not ideal, but it seemed like the best approach I could see given the semantics of the available flags -- I'm open to other possibilities though if there's something else that would work better. Thanks for the review, Zev