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 65AADC433EF for ; Fri, 18 Feb 2022 00:23:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230145AbiBRAYG (ORCPT ); Thu, 17 Feb 2022 19:24:06 -0500 Received: from gmail-smtp-in.l.google.com ([23.128.96.19]:46076 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230092AbiBRAYA (ORCPT ); Thu, 17 Feb 2022 19:24:00 -0500 Received: from thorn.bewilderbeest.net (thorn.bewilderbeest.net [IPv6:2605:2700:0:5::4713:9cab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89E6D377DC; Thu, 17 Feb 2022 16:23:44 -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 319D3FA; Thu, 17 Feb 2022 16:23:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bewilderbeest.net; s=thorn; t=1645143824; bh=b+69uaIlAfYvUutHI5tZxpP8eKuLZSiDYTF3PppxEac=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=M9kSLMcpXIb8BgmOmcCk0mpT/vYbtrX5je5KCdkidZJRInS65T8cKISj2rY/LzhAg XEfJxkqHxQV2FQx0n5qE8duGmjxVuQaIs5xrAP8kvVFWBQ8oX1MavlanSDr2yghP+g w24eCmHVJTCJ4KdP5mUpMnyaALzjWNhlBCdbpLpY= Date: Thu, 17 Feb 2022 16:23:42 -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> <3bfa7f1f-ef5d-b222-894b-b15a2270996d@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3bfa7f1f-ef5d-b222-894b-b15a2270996d@roeck-us.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 17, 2022 at 04:02:58PM PST, Guenter Roeck wrote: >On 2/17/22 15:37, Zev Weiss wrote: >>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. >> > >Ok, that makes sense. > >>>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. >> > >My approach would be to report a warning if no temperature warning/fault >is set from PMBUS_STATUS_TEMPERATURE but PB_STATUS_TEMPERATURE is set >in the status register. > >Something like > > if (!(*flags & (REGULATOR_ERROR_OVER_TEMP | REGULATOR_ERROR_OVER_TEMP_WARN)) > && (status & PB_STATUS_TEMPERATURE)) > *flags |= REGULATOR_ERROR_OVER_TEMP_WARN; > >While not perfect, it would be better than reporting nothing. > That sounds like a good idea -- I'll add it in v2. Thanks, Zev