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Fri, 28 Aug 2026 08:59:55 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:da43:aeff:fecc:bfd5]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-3286f95a160sm6524806eec.18.2026.08.28.08.59.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 28 Aug 2026 08:59:55 -0700 (PDT) Sender: Guenter Roeck Date: Fri, 28 Aug 2026 08:59:53 -0700 From: Guenter Roeck To: Vishnu Razdan Cc: linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org, vikash.chandola@linux.intel.com Subject: Re: [PATCH] hwmon: (pmbus) Clear generic status alarms with CLEAR_FAULTS Message-ID: <53d1d7d5-629e-48fa-8947-3a3c294ff16b@roeck-us.net> References: <20260824-vrazdan-pmbus-status-word-b4-v1-1-2606ecd0c029@openai.com> Precedence: bulk X-Mailing-List: linux-hwmon@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260824-vrazdan-pmbus-status-word-b4-v1-1-2606ecd0c029@openai.com> On Mon, Aug 24, 2026 at 11:58:00PM -0700, Vishnu Razdan wrote: > From: Vishnu Razdan > > Some hwmon alarms fall back to STATUS_WORD summary bits when no > individual limit alarm is available. On PMBus 1.2 and newer devices, > pmbus_get_boolean() acknowledges these alarms with the same byte-data > write used for detailed status registers. For example, PB_STATUS_INPUT > is 0x2000, so it is truncated to zero when passed to > _pmbus_write_byte_data(). The resulting write cannot acknowledge the > input alarm. > > PMBus 1.3 Part II, sections 10.2.4 and 10.2.5, excludes ordinary > STATUS_BYTE and STATUS_WORD summary bits from individual clearing. > Their summary bits clear when the underlying status bits clear, so > changing this to a word-data write would not fix the generic input > alarm either. > > Use the existing page CLEAR_FAULTS path for generic STATUS_WORD > alarms, including devices whose status accessor uses STATUS_BYTE. > Keep individual byte writes for detailed status registers on PMBus > 1.2 and newer devices. As with the existing older-device fallback, > CLEAR_FAULTS can clear other latched status; an active condition can > reassert its status. > > Fixes: 35f165f08950 ("hwmon: (pmbus) Clear pmbus fault/warning bits after read") > Cc: stable@vger.kernel.org > Assisted-by: LLM > Signed-off-by: Vishnu Razdan Applied. Thanks, Guenter