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Fri, 09 Jan 2026 19:48:07 -0800 (PST) Received: from dellphi.android606.com ([2601:644:4784:74b0:c2e:ecff:fed9:d646]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2b175bee31dsm10239900eec.32.2026.01.09.19.48.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Jan 2026 19:48:06 -0800 (PST) From: Andrew Mark To: pali@kernel.org Cc: linux@roeck-us.net, linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Mark Subject: [PATCH] hwmon: (dell-smm) Extend fan support to 5 fans Date: Sat, 10 Jan 2026 03:47:32 +0000 Message-ID: <20260110034732.236285-1-android606@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-hwmon@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Dell Precision Tower workstations have 5 fan connectors, but the driver was limited to 4 fans after commit dbcfcb239b3b ("hwmon: (dell-smm) Increment the number of fans"). This patch increases DELL_SMM_NO_FANS to 5 and adds the necessary hwmon channel info for the fifth fan and its PWM control. Without this patch, the PCIe/GPU cooling fan (fan 5) is not controllable, which can lead to overheating on systems with high-power fanless GPUs that depend on chassis cooling. Also adds a DMI quirk for Precision Tower 5810 to provide accurate fan labels, as the BIOS reports generic types for these fans. Tested on Dell Precision Tower 5810 (BIOS A34) with all 5 fans responding correctly to PWM control. Fan mapping for Precision Tower 5810: - fan0: CPU heatsink - fan1: Second CPU (dual-CPU systems only) - fan2: Right DIMM bank - fan3: Left DIMM bank - fan4: PCIe/GPU cooling Signed-off-by: Andrew Mark --- drivers/hwmon/dell-smm-hwmon.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c index 6040a8940..b112e6fbc 100644 --- a/drivers/hwmon/dell-smm-hwmon.c +++ b/drivers/hwmon/dell-smm-hwmon.c @@ -74,7 +74,7 @@ #define DELL_SMM_LEGACY_EXECUTE 0x1 #define DELL_SMM_NO_TEMP 10 -#define DELL_SMM_NO_FANS 4 +#define DELL_SMM_NO_FANS 5 /* limit fan multiplier to avoid overflow */ #define DELL_SMM_MAX_FAN_MULT (INT_MAX / U16_MAX) @@ -175,6 +175,14 @@ static const char * const docking_labels[] = { "Docking Other Fan", }; +static const char * const precision_tower_5810_labels[] = { + "CPU Fan", + "CPU Fan 2", + "Right DIMM Fan", + "Left DIMM Fan", + "PCIe Fan", +}; + static inline const char __init *i8k_get_dmi_data(int field) { const char *dmi_data = dmi_get_system_info(field); @@ -991,6 +999,12 @@ static const char *dell_smm_fan_label(struct dell_smm_data *data, int channel) if (type < 0) return ERR_PTR(type); + if (dmi_match(DMI_PRODUCT_NAME, "Precision Tower 5810")) { + if (channel < ARRAY_SIZE(precision_tower_5810_labels)) + return precision_tower_5810_labels[channel]; + return "Unknown Fan"; + } + if (type & 0x10) { dock = true; type &= 0x0F; @@ -1129,12 +1143,15 @@ static const struct hwmon_channel_info * const dell_smm_info[] = { HWMON_F_INPUT | HWMON_F_LABEL | HWMON_F_MIN | HWMON_F_MAX | HWMON_F_TARGET, HWMON_F_INPUT | HWMON_F_LABEL | HWMON_F_MIN | HWMON_F_MAX | + HWMON_F_TARGET, + HWMON_F_INPUT | HWMON_F_LABEL | HWMON_F_MIN | HWMON_F_MAX | HWMON_F_TARGET ), HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT | HWMON_PWM_ENABLE, HWMON_PWM_INPUT | HWMON_PWM_ENABLE, HWMON_PWM_INPUT | HWMON_PWM_ENABLE, + HWMON_PWM_INPUT | HWMON_PWM_ENABLE, HWMON_PWM_INPUT | HWMON_PWM_ENABLE ), NULL -- 2.43.0