[PATCH RFC v5 0/7] mfd: ls2kbmc: multiple fixes for this driver

[PATCH RFC v5 0/7] mfd: ls2kbmc: multiple fixes for this driver

[Miao Wang via B4 Relay]

Previously, the driver has been introduced to support the Loongson 2K
BMC running on the Loongson Servers, which is essential to prevent
the system from hanging when the BMC is being reset and the default
efi-framebuffer is being used. However, there are some drawbacks in the
driver.

Firstly, the driver tries to read and write to the connected PCI-E host
controller registers, assuming that the BMC is connected to LS7A PCI-E
host controller. This assumption should be true for real products, but
to prevent from accidentally reading and writing to the wrong PCI-E host
controller, this driver should be modified to check this before
accessing the registers.

Secondly, the driver uses non-exported functions to tell the vt
subsystem to redraw the screen, preventing the driver from being
compiling as a module. This can be fixed by using the exported
functions instead.

Thirdly, the driver directly accesses the GPIO controller registers
using hard-coded addresses, which might conflict with the loaded GPIO
controller driver for the same GPIO controller. This is fixed in this
series by using the GPIO subsystem APIs instead. However, legacy GPIO
APIs have to be used in this fixed to correctly request a GPIO
descriptor from the GPIO subsystem, which might be further discussed
to find a better solution.

Finally, there is a minor issue in the driver where it changes the
mode string describing the screen resolution during probing, which
prevents the device from being probed again if -EPROBE_DEFER is
returned by the probe function.

I have tested the changes in this series on a single-socket Loongson
3C6000 server with a Loongson 2K BMC, and the driver works as expected
when the corresponding GPIO driver is additionally loaded.

Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
---
Changes in v5:
- Address issues found by the Sashiko AI review bot
  - Maintain the compatibility with possible unexpected mode string when
    parsing, although such mode string is actually not expected, to
    satisfy the AI bot's concern.
  - Add a comment to point out that the adjustment of the Kconfig entry
    for ls2kbmc is in the following patch, to satisfy the AI bot's
    concern.
- Link to v4: https://lore.kernel.org/r/20260731-ls2kbmc-mod-v4-0-d201502ba239@gmail.com

Changes in v4:
- Use a better way to get the GPIO device fwnode.
- Add a comment to describe a problem found by AI bot which is actually
  intended.
- Link to v3: https://lore.kernel.org/r/20260710-ls2kbmc-mod-v3-0-ef718636e78e@gmail.com

Changes in v3:
- Check the return value of devm_add_action_or_reset when registering
  the cleanup hook of the work queue
- Use swnode to create the link between the device to the GPIO chip,
  and prevent borrowing the legacy GPIO APIs
- Link to v2: https://lore.kernel.org/r/20260708-ls2kbmc-mod-v2-0-2afdd1741766@gmail.com

Changes in v2:
- Several fixes suggested by the Sashiko AI review bot
- Add a cleanup function for the wq on removal of the device
- Relax the reverse dependency from CONFIG_IPMI_LS2K to
  CONFIG_MFD_LS2K_BMC_CORE to allow the driver to be built as a module
- Link to v1: https://lore.kernel.org/r/20260708-ls2kbmc-mod-v1-0-c344bf5defa3@gmail.com

---
Miao Wang (7):
      mfd: ls2kbmc: Make a copy when parsing mode string
      mfd: ls2kbmc: Sanity check for the connected pci port
      mfd: ls2kbmc: Redraw using exported functions
      mfd: ls2kbmc: Cancel the work queue on removal
      ipmi: ls2k: Relax the dependency to its mfd driver
      mfd: ls2kbmc: Able to be compiled as a module
      mfd: ls2kbmc: Capture the reset event of BMC through GPIO

 drivers/char/ipmi/Kconfig   |   2 +-
 drivers/mfd/Kconfig         |   2 +-
 drivers/mfd/ls2k-bmc-core.c | 246 ++++++++++++++++++++++++++++++++++----------
 3 files changed, 192 insertions(+), 58 deletions(-)
---
base-commit: 11028ab62899e4191e074ee364c712b77823a9c4
change-id: 20260626-ls2kbmc-mod-5209193009b2

Best regards,
-- 
Miao Wang <shankerwangmiao@gmail.com>

[PATCH RFC v5 1/7] mfd: ls2kbmc: Make a copy when parsing mode string

[Miao Wang via B4 Relay]

From: Miao Wang <shankerwangmiao@gmail.com>

When parsing the mode string from BMC, the string is manipulated
in-place with strsep(), preventing from parsing it again. Make a copy of
the original string and manipulate the copy instead to fix this.

Fixes: 0d64f6d1ffe9 ("mfd: ls2kbmc: Introduce Loongson-2K BMC core driver")
Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
---
 drivers/mfd/ls2k-bmc-core.c | 36 ++++++++++++++++++++++++++++--------
 1 file changed, 28 insertions(+), 8 deletions(-)

diff --git a/drivers/mfd/ls2k-bmc-core.c b/drivers/mfd/ls2k-bmc-core.c
index 408056bfb2fe757a5bde43775a483a48352e706d..fc9695eedd3662ac92ff116811bb07bff1c994ea 100644
--- a/drivers/mfd/ls2k-bmc-core.c
+++ b/drivers/mfd/ls2k-bmc-core.c
@@ -427,34 +427,54 @@ static int ls2k_bmc_init(struct ls2k_bmc_ddata *ddata)
  */
 static int ls2k_bmc_parse_mode(struct pci_dev *pdev, struct simplefb_platform_data *pd)
 {
-	char *mode;
+	/* Assume 64 bytes is enough for the resolution string */
+	char mode_buf[64], mode_buf_orig[64];
+	char *mode = mode_buf;
+	const void __iomem *mode_base;
 	int depth, ret;
 
 	/* The last 16M of PCI BAR0 is used to store the resolution string. */
-	mode = devm_ioremap(&pdev->dev, pci_resource_start(pdev, 0) + SZ_16M, SZ_16M);
-	if (!mode)
+	mode_base = ioremap(pci_resource_start(pdev, 0) + SZ_16M,
+			    sizeof(mode_buf));
+	if (!mode_base)
 		return -ENOMEM;
+	memcpy_fromio(mode_buf, mode_base, sizeof(mode_buf) - 1);
+	mode_buf[sizeof(mode_buf) - 1] = '\0';
+	iounmap((void __iomem *)mode_base);
+	memcpy(mode_buf_orig, mode_buf, sizeof(mode_buf_orig));
 
 	/* The resolution field starts with the flag "video=". */
 	if (!strncmp(mode, "video=", 6))
 		mode = mode + 6;
 
-	ret = kstrtoint(strsep(&mode, "x"), 10, &pd->width);
+	ret = kstrtouint(strsep(&mode, "x"), 10, &pd->width);
 	if (ret)
-		return ret;
+		goto invalid_mode;
 
-	ret = kstrtoint(strsep(&mode, "-"), 10, &pd->height);
+	if (mode == NULL) {
+		ret = -EINVAL;
+		goto invalid_mode;
+	}
+	ret = kstrtouint(strsep(&mode, "-"), 10, &pd->height);
 	if (ret)
-		return ret;
+		goto invalid_mode;
 
+	if (mode == NULL) {
+		ret = -EINVAL;
+		goto invalid_mode;
+	}
 	ret = kstrtoint(strsep(&mode, "@"), 10, &depth);
 	if (ret)
-		return ret;
+		goto invalid_mode;
 
 	pd->stride = pd->width * depth / 8;
 	pd->format = depth == 32 ? "a8r8g8b8" : "r5g6b5";
 
 	return 0;
+
+invalid_mode:
+	dev_err(&pdev->dev, "Invalid resolution string: %s\n", mode_buf_orig);
+	return ret;
 }
 
 static int ls2k_bmc_probe(struct pci_dev *dev, const struct pci_device_id *id)

-- 
2.49.0

[PATCH RFC v5 2/7] mfd: ls2kbmc: Sanity check for the connected pci port

[Miao Wang via B4 Relay]

From: Miao Wang <shankerwangmiao@gmail.com>

When the bmc resets, the recovery procedure require to reconfigure the
parent device. The driver assumes that the parent device should be LS7A.
Add a sanity check on initialization to ensure this and prevent from
accidentally operating on non-LS7A ports.

Fixes: d952bba3fbb5 ("mfd: ls2kbmc: Add Loongson-2K BMC reset function support")
Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
---
 drivers/mfd/ls2k-bmc-core.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/mfd/ls2k-bmc-core.c b/drivers/mfd/ls2k-bmc-core.c
index fc9695eedd3662ac92ff116811bb07bff1c994ea..a9a30611dde9e31cd86ff67b1d6e02bf67b34755 100644
--- a/drivers/mfd/ls2k-bmc-core.c
+++ b/drivers/mfd/ls2k-bmc-core.c
@@ -35,6 +35,15 @@
 #define LS2K_IPMI3_RES_START		(LS2K_IPMI2_RES_START + LS2K_IPMI_RES_SIZE)
 #define LS2K_IPMI4_RES_START		(LS2K_IPMI3_RES_START + LS2K_IPMI_RES_SIZE)
 
+/* LS7A port Device IDs */
+#define DEV_LS7A1K_PCIE_PORT0	0x7a09
+#define DEV_LS7A1K_PCIE_PORT1	0x7a19
+#define DEV_LS7A1K_PCIE_PORT2	0x7a29
+#define DEV_LS7A2K_PCIE_PORT0	0x7a39
+#define DEV_LS7A2K_PCIE_PORT1	0x7a49
+#define DEV_LS7A2K_PCIE_PORT2	0x7a59
+#define DEV_LS7A2K_PCIE_PORT3	0x7a69
+
 #define LS7A_PCI_CFG_SIZE		0x100
 
 /* LS7A bridge registers */
@@ -477,6 +486,24 @@ static int ls2k_bmc_parse_mode(struct pci_dev *pdev, struct simplefb_platform_da
 	return ret;
 }
 
+static const struct pci_device_id ls7a_ports[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, DEV_LS7A1K_PCIE_PORT0) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, DEV_LS7A1K_PCIE_PORT1) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, DEV_LS7A1K_PCIE_PORT2) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, DEV_LS7A2K_PCIE_PORT0) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, DEV_LS7A2K_PCIE_PORT1) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, DEV_LS7A2K_PCIE_PORT2) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_LOONGSON, DEV_LS7A2K_PCIE_PORT3) },
+	{ }
+};
+
+static bool ls2k_check_parent(struct pci_dev *dev)
+{
+	struct pci_dev *parent = dev->bus->self;
+
+	return parent && pci_match_id(ls7a_ports, parent) != NULL;
+}
+
 static int ls2k_bmc_probe(struct pci_dev *dev, const struct pci_device_id *id)
 {
 	struct simplefb_platform_data pd;
@@ -488,6 +515,11 @@ static int ls2k_bmc_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	if (ret)
 		return ret;
 
+	if (!ls2k_check_parent(dev)) {
+		dev_err(&dev->dev, "Expected to be connected to LS7A PCI-E port\n");
+		return -ENODEV;
+	}
+
 	ddata = devm_kzalloc(&dev->dev, sizeof(*ddata), GFP_KERNEL);
 	if (!ddata)
 		return -ENOMEM;

-- 
2.49.0

[PATCH RFC v5 3/7] mfd: ls2kbmc: Redraw using exported functions

[Miao Wang via B4 Relay]

From: Miao Wang <shankerwangmiao@gmail.com>

Use update_screen, i.e. redraw_screen() to trigger the redraw of the
current vt.

Fixes: d952bba3fbb5 ("mfd: ls2kbmc: Add Loongson-2K BMC reset function support")
Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
---
 drivers/mfd/ls2k-bmc-core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/mfd/ls2k-bmc-core.c b/drivers/mfd/ls2k-bmc-core.c
index a9a30611dde9e31cd86ff67b1d6e02bf67b34755..e12f2ca2fbef360ceda14ee6fc64f500e4944120 100644
--- a/drivers/mfd/ls2k-bmc-core.c
+++ b/drivers/mfd/ls2k-bmc-core.c
@@ -25,6 +25,7 @@
 #include <linux/platform_device.h>
 #include <linux/stop_machine.h>
 #include <linux/vt_kern.h>
+#include <linux/console.h>
 
 /* LS2K BMC resources */
 #define LS2K_DISPLAY_RES_START		(SZ_16M + SZ_2M)
@@ -310,7 +311,9 @@ static void ls2k_bmc_events_fn(struct work_struct *work)
 
 	if (IS_ENABLED(CONFIG_VT)) {
 		/* Re-push the display due to previous PCI-E loss. */
-		set_console(vt_move_to_console(MAX_NR_CONSOLES - 1, 1));
+		console_lock();
+		update_screen(vc_cons[fg_console].d);
+		console_unlock();
 	}
 }
 

-- 
2.49.0

[PATCH RFC v5 4/7] mfd: ls2kbmc: Cancel the work queue on removal

[Miao Wang via B4 Relay]

From: Miao Wang <shankerwangmiao@gmail.com>

When the device is being removeed, the work queue should be canceled to
avoid any pending work to be executed after the device is removed.

Fixes: d952bba3fbb5 ("mfd: ls2kbmc: Add Loongson-2K BMC reset function support")
Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
---
 drivers/mfd/ls2k-bmc-core.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/mfd/ls2k-bmc-core.c b/drivers/mfd/ls2k-bmc-core.c
index e12f2ca2fbef360ceda14ee6fc64f500e4944120..e7bebfe696ac4554eb6283279811a27ed865ab73 100644
--- a/drivers/mfd/ls2k-bmc-core.c
+++ b/drivers/mfd/ls2k-bmc-core.c
@@ -375,6 +375,12 @@ static void ls2k_bmc_save_pci_data(struct pci_dev *pdev, struct ls2k_bmc_ddata *
 	pci_read_config_dword(pdev, PCI_INTERRUPT_LINE, &ddata->bmc_pci_data.interrupt_line);
 }
 
+static void ls2k_bmc_cancel_wq(void *data)
+{
+	struct ls2k_bmc_ddata *ddata = data;
+	(void) cancel_work_sync(&ddata->bmc_reset_work);
+}
+
 static int ls2k_bmc_init(struct ls2k_bmc_ddata *ddata)
 {
 	struct pci_dev *pdev = to_pci_dev(ddata->dev);
@@ -385,6 +391,10 @@ static int ls2k_bmc_init(struct ls2k_bmc_ddata *ddata)
 
 	INIT_WORK(&ddata->bmc_reset_work, ls2k_bmc_events_fn);
 
+	ret = devm_add_action_or_reset(ddata->dev, ls2k_bmc_cancel_wq, ddata);
+	if (ret)
+		return ret;
+
 	ret = devm_request_irq(&pdev->dev, pdev->irq, ls2k_bmc_interrupt,
 			       IRQF_SHARED | IRQF_TRIGGER_FALLING, "ls2kbmc pcie", ddata);
 	if (ret) {

-- 
2.49.0

[PATCH RFC v5 5/7] ipmi: ls2k: Relax the dependency to its mfd driver

[Miao Wang via B4 Relay]

From: Miao Wang <shankerwangmiao@gmail.com>

There is no strong dependency between the IPMI driver and its mfd
driver. Although the IPMI driver will not work without the mfd driver,
it is not a hard dependency. The IPMI driver can actually be compiled
without the mfd driver, and it will just fail to probe. When the mfd
driver is loaded, the IPMI driver will probe successfully. Therefore,
the dependency of the IPMI driver on its mfd driver should be relaxed
to "imply" from "select". This will allow the mfd driver to be compiled
as a module and the IPMI driver to be compiled as a part of the ipmi_si
module. The adjustment to Kconfig for the mfd driver will be introduced
in the later patch in this series.

Fixes: d46651d4e3c0 ("ipmi: Add Loongson-2K BMC support")
Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
---
 drivers/char/ipmi/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
index 669f7600019747bcd2b37563477cf336f19a0407..f456e3e89416932f0d21bb742153a503aeb24267 100644
--- a/drivers/char/ipmi/Kconfig
+++ b/drivers/char/ipmi/Kconfig
@@ -87,7 +87,7 @@ config IPMI_IPMB
 config IPMI_LS2K
 	bool 'Loongson-2K IPMI interface'
 	depends on LOONGARCH
-	select MFD_LS2K_BMC_CORE
+	imply MFD_LS2K_BMC_CORE
 	help
 	  Provides a driver for Loongson-2K IPMI interfaces.
 

-- 
2.49.0

[PATCH RFC v5 6/7] mfd: ls2kbmc: Able to be compiled as a module

[Miao Wang via B4 Relay]

From: Miao Wang <shankerwangmiao@gmail.com>

Make ls2kmc able to be compiled as a module

Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
---
 drivers/mfd/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 763ce6a34782bdd5d2b1a4d840c75b040092d83e..a7a9f97af248c88489dc1203a1ba05f2ce4827df 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -2494,7 +2494,7 @@ config MFD_LOONGSON_SE
 	  which will forward them to the corresponding engine.
 
 config MFD_LS2K_BMC_CORE
-	bool "Loongson-2K Board Management Controller Support"
+	tristate "Loongson-2K Board Management Controller Support"
 	depends on PCI && ACPI_GENERIC_GSI
 	select MFD_CORE
 	help

-- 
2.49.0

[PATCH RFC v5 7/7] mfd: ls2kbmc: Capture the reset event of BMC through GPIO

[Miao Wang via B4 Relay]

From: Miao Wang <shankerwangmiao@gmail.com>

The reset event of BMC is captured through GPIO. However, this driver
bypasses the GPIO framework and directly accesses the GPIO controller
through the fixed address. When the same GPIO controller is also
exposed through ACPI and probed by the corresponding GPIO driver,
there would be a conflict between the two drivers.

This patch will try to find the GPIO through declared GPIO pin in the
_CRS resources of the ACPI node. If no such delaration is found, the
driver will fall back to search for the correct GPIO controller and pin
according to the fixed address and pin number. A possible DSDT
declaration for the GPIO pin might be as follows:

    Device (BMC0) {
        Name (_ADR, ...) // Match the PCI address of the BMC device
        // \_SB.GPO1 is the ACPI path of the GPIO controller
        Name (_CRS, ResourceTemplate () {
            GpioInt (Edge, ActiveLow, Exclusive, PullNone, 0,
                     "\\_SB.GPO1", 0) {
                14 // 14 is the GPIO pin number
            }
    }

Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
---
 drivers/mfd/ls2k-bmc-core.c | 163 +++++++++++++++++++++++++++++++-------------
 1 file changed, 116 insertions(+), 47 deletions(-)

diff --git a/drivers/mfd/ls2k-bmc-core.c b/drivers/mfd/ls2k-bmc-core.c
index e7bebfe696ac4554eb6283279811a27ed865ab73..97a666a136fe41ed4268cb70770201533aebb1d5 100644
--- a/drivers/mfd/ls2k-bmc-core.c
+++ b/drivers/mfd/ls2k-bmc-core.c
@@ -26,6 +26,10 @@
 #include <linux/stop_machine.h>
 #include <linux/vt_kern.h>
 #include <linux/console.h>
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/property.h>
+#include <linux/gpio/machine.h>
 
 /* LS2K BMC resources */
 #define LS2K_DISPLAY_RES_START		(SZ_16M + SZ_2M)
@@ -81,18 +85,6 @@
 
 #define PCI_REG_STRIDE			0x4
 
-#define LS2K_BMC_RESET_GPIO		14
-#define LOONGSON_GPIO_REG_BASE		0x1FE00500
-#define LOONGSON_GPIO_REG_SIZE		0x18
-#define LOONGSON_GPIO_OEN		0x0
-#define LOONGSON_GPIO_FUNC		0x4
-#define LOONGSON_GPIO_INTPOL		0x10
-#define LOONGSON_GPIO_INTEN		0x14
-
-#define LOONGSON_IO_INT_BASE		16
-#define LS2K_BMC_RESET_GPIO_INT_VEC	(LS2K_BMC_RESET_GPIO % 8)
-#define LS2K_BMC_RESET_GPIO_GSI		(LOONGSON_IO_INT_BASE + LS2K_BMC_RESET_GPIO_INT_VEC)
-
 enum {
 	LS2K_BMC_DISPLAY,
 	LS2K_BMC_IPMI0,
@@ -186,6 +178,7 @@ struct ls2k_bmc_ddata {
 	struct work_struct bmc_reset_work;
 	struct ls2k_bmc_pci_data bmc_pci_data;
 	struct ls2k_bmc_bridge_pci_data bridge_pci_data;
+	struct gpio_desc *reset_gpio;
 };
 
 static bool ls2k_bmc_bar0_addr_is_set(struct pci_dev *pdev)
@@ -375,6 +368,91 @@ static void ls2k_bmc_save_pci_data(struct pci_dev *pdev, struct ls2k_bmc_ddata *
 	pci_read_config_dword(pdev, PCI_INTERRUPT_LINE, &ddata->bmc_pci_data.interrupt_line);
 }
 
+static struct fwnode_handle *gpio_dev_get_fwnode(struct gpio_device *gdev)
+{
+	struct device *gdev_dev;
+
+	gdev_dev = gpio_device_to_device(gdev);
+	return dev_fwnode(gdev_dev);
+}
+
+static int ls2k_bmc_gpiochip_find(struct gpio_chip *gc, const void *data)
+{
+	struct acpi_device *adev;
+	struct list_head resource_list;
+	struct resource_entry *rentry;
+	struct fwnode_handle *fwnode = gpio_dev_get_fwnode(gc->gpiodev);
+	phys_addr_t start_addr = (phys_addr_t) data;
+	int ret, found = 0;
+
+	if (!is_acpi_node(fwnode))
+		goto out;
+
+	adev = to_acpi_device_node(fwnode);
+	if (!adev)
+		goto out;
+
+	INIT_LIST_HEAD(&resource_list);
+
+	ret = acpi_dev_get_memory_resources(adev, &resource_list);
+	if (ret < 0)
+		goto out;
+	/*
+	 * ACPI memory resources are ordered and only the first one is
+	 * considered by the driver of the expected GPIO controller. So
+	 * here we also only check the first one to see if it matches the
+	 * expected address.
+	 */
+	rentry = list_first_entry_or_null(&resource_list, struct resource_entry, node);
+	if (!rentry)
+		goto free_resource_list;
+	if (rentry->res->start == start_addr)
+		found = 1;
+
+free_resource_list:
+	acpi_dev_free_resource_list(&resource_list);
+out:
+	return found;
+}
+
+static struct gpio_desc *ls2k_bmc_find_gpio(struct ls2k_bmc_ddata *ddata)
+{
+	/*
+	 * In conventional way, the GPIO should be obtained through ACPI or
+	 * device tree. However, when the information is not available,
+	 * we should find the GPIO according to the convention of the server
+	 * boards with LS2K BMC, the gpio signal reflecting the reset event
+	 * of the BMC should be connected to pin 14 of the GPIO input of
+	 * the first CPU node. The address of that GPIO controller is fixed.
+	 */
+	static const phys_addr_t LOONGSON_GPIO_REG_BASE = 0x1FE00500;
+	static const unsigned int LS2K_BMC_RESET_GPIO = 14;
+	int ret;
+	struct gpio_device *gdev __free(gpio_device_put) = NULL;
+	struct property_entry ls2k_bmc_swnode_properties[2] = { 0 };
+
+	dev_dbg(ddata->dev, "Searching for GPIO chip at address %pa\n", &LOONGSON_GPIO_REG_BASE);
+
+	gdev = gpio_device_find((void *)LOONGSON_GPIO_REG_BASE, ls2k_bmc_gpiochip_find);
+
+	if (!gdev) {
+		dev_dbg(ddata->dev, "cannot find GPIO chip at address %pa, deferring\n",
+			&LOONGSON_GPIO_REG_BASE);
+		return ERR_PTR(-EPROBE_DEFER);
+	}
+
+	ls2k_bmc_swnode_properties[0] = PROPERTY_ENTRY_GPIO("gpio",
+		gpio_dev_get_fwnode(gdev), LS2K_BMC_RESET_GPIO, GPIO_ACTIVE_HIGH);
+
+	ret = device_create_managed_software_node(ddata->dev, ls2k_bmc_swnode_properties, NULL);
+	if (ret) {
+		dev_err(ddata->dev, "Failed to create software node for GPIO reset: %d\n", ret);
+		return ERR_PTR(ret);
+	}
+
+	return devm_gpiod_get_index(ddata->dev, NULL, 0, GPIOD_IN);
+}
+
 static void ls2k_bmc_cancel_wq(void *data)
 {
 	struct ls2k_bmc_ddata *ddata = data;
@@ -384,8 +462,7 @@ static void ls2k_bmc_cancel_wq(void *data)
 static int ls2k_bmc_init(struct ls2k_bmc_ddata *ddata)
 {
 	struct pci_dev *pdev = to_pci_dev(ddata->dev);
-	void __iomem *gpio_base;
-	int gpio_irq, ret, val;
+	int gpio_irq, ret;
 
 	ls2k_bmc_save_pci_data(pdev, ddata);
 
@@ -402,44 +479,36 @@ static int ls2k_bmc_init(struct ls2k_bmc_ddata *ddata)
 		return ret;
 	}
 
-	gpio_base = ioremap(LOONGSON_GPIO_REG_BASE, LOONGSON_GPIO_REG_SIZE);
-	if (!gpio_base)
-		return -ENOMEM;
-
-	/* Disable GPIO output */
-	val = readl(gpio_base + LOONGSON_GPIO_OEN);
-	writel(val | BIT(LS2K_BMC_RESET_GPIO), gpio_base + LOONGSON_GPIO_OEN);
-
-	/* Enable GPIO functionality */
-	val = readl(gpio_base + LOONGSON_GPIO_FUNC);
-	writel(val & ~BIT(LS2K_BMC_RESET_GPIO), gpio_base + LOONGSON_GPIO_FUNC);
-
-	/* Set GPIO interrupts to low-level active */
-	val = readl(gpio_base + LOONGSON_GPIO_INTPOL);
-	writel(val & ~BIT(LS2K_BMC_RESET_GPIO), gpio_base + LOONGSON_GPIO_INTPOL);
-
-	/* Enable GPIO interrupts */
-	val = readl(gpio_base + LOONGSON_GPIO_INTEN);
-	writel(val | BIT(LS2K_BMC_RESET_GPIO), gpio_base + LOONGSON_GPIO_INTEN);
+	ddata->reset_gpio = devm_gpiod_get_index_optional(&pdev->dev, NULL, 0, GPIOD_IN);
+	if (IS_ERR(ddata->reset_gpio)) {
+		ret = PTR_ERR(ddata->reset_gpio);
+		ddata->reset_gpio = NULL;
+		return dev_err_probe(ddata->dev, ret, "Failed to get GPIO pin for reset signal\n");
+	}
+	if (ddata->reset_gpio == NULL) {
+		ddata->reset_gpio = ls2k_bmc_find_gpio(ddata);
+		if (IS_ERR(ddata->reset_gpio)) {
+			ret = PTR_ERR(ddata->reset_gpio);
+			ddata->reset_gpio = NULL;
+			return dev_err_probe(ddata->dev, ret,
+					     "Failed to find GPIO pin for reset signal\n");
+		}
+	}
 
-	iounmap(gpio_base);
+	gpio_irq = gpiod_to_irq(ddata->reset_gpio);
 
-	/*
-	 * Since gpio_chip->to_irq is not implemented in the Loongson-3 GPIO driver,
-	 * acpi_register_gsi() is used to obtain the GPIO IRQ. The GPIO interrupt is a
-	 * watchdog interrupt that is triggered when the BMC resets.
-	 */
-	gpio_irq = acpi_register_gsi(NULL, LS2K_BMC_RESET_GPIO_GSI, ACPI_EDGE_SENSITIVE,
-				     ACPI_ACTIVE_LOW);
 	if (gpio_irq < 0)
-		return gpio_irq;
+		return dev_err_probe(ddata->dev, gpio_irq,
+				     "Failed to get IRQ for GPIO reset signal input\n");
 
-	ret = devm_request_irq(ddata->dev, gpio_irq, ls2k_bmc_interrupt,
-			       IRQF_SHARED | IRQF_TRIGGER_FALLING, "ls2kbmc gpio", ddata);
-	if (ret)
-		dev_err(ddata->dev, "Failed to request LS2KBMC GPIO IRQ %d.\n", gpio_irq);
+	ret = devm_request_irq(&pdev->dev, gpio_irq, ls2k_bmc_interrupt,
+			       IRQF_SHARED | IRQF_TRIGGER_FALLING, "ls2kbmc reset", ddata);
+
+	if (ret != 0)
+		return dev_err_probe(ddata->dev, ret,
+				     "Failed to request IRQ %d for GPIO reset signal input.\n",
+				     gpio_irq);
 
-	acpi_unregister_gsi(LS2K_BMC_RESET_GPIO_GSI);
 	return ret;
 }
 

-- 
2.49.0

Re: [PATCH RFC v5 5/7] ipmi: ls2k: Relax the dependency to its mfd driver

[Corey Minyard]

On Tue, Aug 04, 2026 at 12:55:53AM +0800, Miao Wang via B4 Relay wrote:
> From: Miao Wang <shankerwangmiao@gmail.com>
> 
> There is no strong dependency between the IPMI driver and its mfd
> driver. Although the IPMI driver will not work without the mfd driver,
> it is not a hard dependency. The IPMI driver can actually be compiled
> without the mfd driver, and it will just fail to probe. When the mfd
> driver is loaded, the IPMI driver will probe successfully. Therefore,
> the dependency of the IPMI driver on its mfd driver should be relaxed
> to "imply" from "select". This will allow the mfd driver to be compiled
> as a module and the IPMI driver to be compiled as a part of the ipmi_si
> module. The adjustment to Kconfig for the mfd driver will be introduced
> in the later patch in this series.

I don't think that's what "imply" is for.  Imply seems to be for if
there is another subsystem that can use this subsystem, but doesn't
require it to exist.

For instance:

config SENSORS_NPCM7XX
        tristate "Nuvoton NPCM750 and compatible PWM and Fan controllers"
        imply THERMAL

The fan controller will work fine without the thermal subsystem; you
can control the fan speed without it.  But the thermal subsystem is the
logical user of this.  I looked at many of these things like this.

In the IPMI case, the IPMI driver is useless without the mfd part.  So
there's no point in compiling the IPMI part of this if the mfd part is
not there.

I could be wrong, but I can't see why you would want to do this.

-corey

> 
> Fixes: d46651d4e3c0 ("ipmi: Add Loongson-2K BMC support")
> Signed-off-by: Miao Wang <shankerwangmiao@gmail.com>
> ---
>  drivers/char/ipmi/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
> index 669f7600019747bcd2b37563477cf336f19a0407..f456e3e89416932f0d21bb742153a503aeb24267 100644
> --- a/drivers/char/ipmi/Kconfig
> +++ b/drivers/char/ipmi/Kconfig
> @@ -87,7 +87,7 @@ config IPMI_IPMB
>  config IPMI_LS2K
>  	bool 'Loongson-2K IPMI interface'
>  	depends on LOONGARCH
> -	select MFD_LS2K_BMC_CORE
> +	imply MFD_LS2K_BMC_CORE
>  	help
>  	  Provides a driver for Loongson-2K IPMI interfaces.
>  
> 
> -- 
> 2.49.0
> 
> 

Re: [PATCH RFC v5 5/7] ipmi: ls2k: Relax the dependency to its mfd driver

[Miao Wang]

Hi,

> 2026年8月4日 04:46，Corey Minyard <corey@minyard.net> 写道：
> 
> On Tue, Aug 04, 2026 at 12:55:53AM +0800, Miao Wang via B4 Relay wrote:
>> From: Miao Wang <shankerwangmiao@gmail.com>
>> 
>> There is no strong dependency between the IPMI driver and its mfd
>> driver. Although the IPMI driver will not work without the mfd driver,
>> it is not a hard dependency. The IPMI driver can actually be compiled
>> without the mfd driver, and it will just fail to probe. When the mfd
>> driver is loaded, the IPMI driver will probe successfully. Therefore,
>> the dependency of the IPMI driver on its mfd driver should be relaxed
>> to "imply" from "select". This will allow the mfd driver to be compiled
>> as a module and the IPMI driver to be compiled as a part of the ipmi_si
>> module. The adjustment to Kconfig for the mfd driver will be introduced
>> in the later patch in this series.
> 
> I don't think that's what "imply" is for.  Imply seems to be for if
> there is another subsystem that can use this subsystem, but doesn't
> require it to exist.
> 
> For instance:
> 
> config SENSORS_NPCM7XX
>        tristate "Nuvoton NPCM750 and compatible PWM and Fan controllers"
>        imply THERMAL
> 
> The fan controller will work fine without the thermal subsystem; you
> can control the fan speed without it.  But the thermal subsystem is the
> logical user of this.  I looked at many of these things like this.
> 
> In the IPMI case, the IPMI driver is useless without the mfd part.  So
> there's no point in compiling the IPMI part of this if the mfd part is
> not there.
> 
> I could be wrong, but I can't see why you would want to do this.

The mfd part and the IPMI part loosely depend on each other. Without the
IPMI part, the mfd part can still work to handle the display part.
Without the mfd part, the IPMI part is indeed useless, but it will not
generate compiling errors or other runtime errors. In the runtime,
the IPMI part can be actually loaded earlier than the mfd part. As a
result, their dependency is not that strong.

The reason why I want to change this is that "select" here requires the
mfd part should also be compiled as built-in (i.e. = y), since the
type of the configure entry IPMI_LS2K is bool. However, I cannot see
there is no other reason preventing the mfd driver from compiling as
a module. This patch series will introduce a minor fix, after which
the mfd driver will be capable to be compiled as a module.

When the type of MFD_LS2K_BMC_CORE is changed to tristate, the "select"
here will prevent selecting =m for MFD_LS2K_BMC_CORE. I thus believe
that "select" here should be also changed.

Any suggestions on declaring the dependency of the both parts?

Cheers,

Miao Wang

Re: [PATCH RFC v5 5/7] ipmi: ls2k: Relax the dependency to its mfd driver

[Corey Minyard]

On Tue, Aug 04, 2026 at 05:40:14PM +0800, Miao Wang wrote:
> Hi,
> 
> > 2026年8月4日 04:46，Corey Minyard <corey@minyard.net> 写道：
> > 
> > On Tue, Aug 04, 2026 at 12:55:53AM +0800, Miao Wang via B4 Relay wrote:
> >> From: Miao Wang <shankerwangmiao@gmail.com>
> >> 
> >> There is no strong dependency between the IPMI driver and its mfd
> >> driver. Although the IPMI driver will not work without the mfd driver,
> >> it is not a hard dependency. The IPMI driver can actually be compiled
> >> without the mfd driver, and it will just fail to probe. When the mfd
> >> driver is loaded, the IPMI driver will probe successfully. Therefore,
> >> the dependency of the IPMI driver on its mfd driver should be relaxed
> >> to "imply" from "select". This will allow the mfd driver to be compiled
> >> as a module and the IPMI driver to be compiled as a part of the ipmi_si
> >> module. The adjustment to Kconfig for the mfd driver will be introduced
> >> in the later patch in this series.
> > 
> > I don't think that's what "imply" is for.  Imply seems to be for if
> > there is another subsystem that can use this subsystem, but doesn't
> > require it to exist.
> > 
> > For instance:
> > 
> > config SENSORS_NPCM7XX
> >        tristate "Nuvoton NPCM750 and compatible PWM and Fan controllers"
> >        imply THERMAL
> > 
> > The fan controller will work fine without the thermal subsystem; you
> > can control the fan speed without it.  But the thermal subsystem is the
> > logical user of this.  I looked at many of these things like this.
> > 
> > In the IPMI case, the IPMI driver is useless without the mfd part.  So
> > there's no point in compiling the IPMI part of this if the mfd part is
> > not there.
> > 
> > I could be wrong, but I can't see why you would want to do this.
> 
> The mfd part and the IPMI part loosely depend on each other. Without the
> IPMI part, the mfd part can still work to handle the display part.
> Without the mfd part, the IPMI part is indeed useless, but it will not
> generate compiling errors or other runtime errors. In the runtime,
> the IPMI part can be actually loaded earlier than the mfd part. As a
> result, their dependency is not that strong.

The operational dependency is strong, which is what I think you want to
convey here.

> 
> The reason why I want to change this is that "select" here requires the
> mfd part should also be compiled as built-in (i.e. = y), since the
> type of the configure entry IPMI_LS2K is bool. However, I cannot see
> there is no other reason preventing the mfd driver from compiling as
> a module. This patch series will introduce a minor fix, after which
> the mfd driver will be capable to be compiled as a module.
> 
> When the type of MFD_LS2K_BMC_CORE is changed to tristate, the "select"
> here will prevent selecting =m for MFD_LS2K_BMC_CORE. I thus believe
> that "select" here should be also changed.
> 
> Any suggestions on declaring the dependency of the both parts?

Ok, I understand now.

Why can't the IPMI part be compiled as a module?  Making that
module-capable would be the right fix, I think.  I can't see
why that wouldn't work.  IIRC, it was bool because the mfd part
was bool.

If you changed to imply, you would need a depends on the mfd core, BTW.

Also, IPMI_LS2K needs a "depends on IPMI_SI" either way.  I missed that
earlier.  Could you add that?

Thanks,

-corey

> 
> Cheers,
> 
> Miao Wang

Re: [PATCH RFC v5 5/7] ipmi: ls2k: Relax the dependency to its mfd driver

[Miao Wang]

Hi,

> 2026年8月4日 19:39，Corey Minyard <corey@minyard.net> 写道：
> 
> On Tue, Aug 04, 2026 at 05:40:14PM +0800, Miao Wang wrote:
>> Hi,
>> 
>>> 2026年8月4日 04:46，Corey Minyard <corey@minyard.net> 写道：
>>> 
>>> On Tue, Aug 04, 2026 at 12:55:53AM +0800, Miao Wang via B4 Relay wrote:
>>>> From: Miao Wang <shankerwangmiao@gmail.com>
>>>> 
>>>> There is no strong dependency between the IPMI driver and its mfd
>>>> driver. Although the IPMI driver will not work without the mfd driver,
>>>> it is not a hard dependency. The IPMI driver can actually be compiled
>>>> without the mfd driver, and it will just fail to probe. When the mfd
>>>> driver is loaded, the IPMI driver will probe successfully. Therefore,
>>>> the dependency of the IPMI driver on its mfd driver should be relaxed
>>>> to "imply" from "select". This will allow the mfd driver to be compiled
>>>> as a module and the IPMI driver to be compiled as a part of the ipmi_si
>>>> module. The adjustment to Kconfig for the mfd driver will be introduced
>>>> in the later patch in this series.
>>> 
>>> I don't think that's what "imply" is for.  Imply seems to be for if
>>> there is another subsystem that can use this subsystem, but doesn't
>>> require it to exist.
>>> 
>>> For instance:
>>> 
>>> config SENSORS_NPCM7XX
>>>       tristate "Nuvoton NPCM750 and compatible PWM and Fan controllers"
>>>       imply THERMAL
>>> 
>>> The fan controller will work fine without the thermal subsystem; you
>>> can control the fan speed without it.  But the thermal subsystem is the
>>> logical user of this.  I looked at many of these things like this.
>>> 
>>> In the IPMI case, the IPMI driver is useless without the mfd part.  So
>>> there's no point in compiling the IPMI part of this if the mfd part is
>>> not there.
>>> 
>>> I could be wrong, but I can't see why you would want to do this.
>> 
>> The mfd part and the IPMI part loosely depend on each other. Without the
>> IPMI part, the mfd part can still work to handle the display part.
>> Without the mfd part, the IPMI part is indeed useless, but it will not
>> generate compiling errors or other runtime errors. In the runtime,
>> the IPMI part can be actually loaded earlier than the mfd part. As a
>> result, their dependency is not that strong.
> 
> The operational dependency is strong, which is what I think you want to
> convey here.
> 
>> 
>> The reason why I want to change this is that "select" here requires the
>> mfd part should also be compiled as built-in (i.e. = y), since the
>> type of the configure entry IPMI_LS2K is bool. However, I cannot see
>> there is no other reason preventing the mfd driver from compiling as
>> a module. This patch series will introduce a minor fix, after which
>> the mfd driver will be capable to be compiled as a module.
>> 
>> When the type of MFD_LS2K_BMC_CORE is changed to tristate, the "select"
>> here will prevent selecting =m for MFD_LS2K_BMC_CORE. I thus believe
>> that "select" here should be also changed.
>> 
>> Any suggestions on declaring the dependency of the both parts?
> 
> Ok, I understand now.
> 
> Why can't the IPMI part be compiled as a module?  Making that
> module-capable would be the right fix, I think.  I can't see
> why that wouldn't work.  IIRC, it was bool because the mfd part
> was bool.

I would have agree with you if the IPMI part was a normal driver.
However, the IPMI part is actually a part of ipmi_si. As a result,
the IPMI part can actually be compiled as a module, but as a part
of ipmi_si. That is why the configure entry IPMI_LS2K is bool rather
than tristate. I don't think it is trivial to convert IPMI_LS2K from
bool to tristate.

> If you changed to imply, you would need a depends on the mfd core, BTW.

If imply is used here, and there is "select MFD_CORE" in MFD_LS2K_BMC_CORE,
I think there is no need to add "depends on MFD_CORE" to IPMI_LS2K, if I
understand it correctly.

I don't insist using imply here, if there is a better way to express the
relation between both drivers.

> Also, IPMI_LS2K needs a "depends on IPMI_SI" either way.  I missed that
> earlier.  Could you add that?

If I understand it correctly, there seems to be no need to add the
dependency from the MFD driver to the driver for the actual sub-functions.
Examples are:

- MFD_MENF21BMC and SENSORS_MENF21BMC_HWMON, LEDS_MENF21BMC, 
  MENF21BMC_WATCHDOG: The later three declared depends on the former MFD
  driver
- MFD_INTEL_M10_BMC_CORE and FPGA_M10_BMC_SEC_UPDATE, 
  SENSORS_INTEL_M10_BMC_HWMON: The later two declared depends on the
  former MFD driver.
- MFD_STMFX and PINCTRL_STMFX: The later declared select the former
  MFD driver.

To summarize, as shown in the current mfd drivers, there is no need to
declare dependency to the drivers providing the sub-functions in the
mfd drivers, and the drivers of the sub functions should "depends on" or
"select" the mfd driver. So if IPMI_LS2K could be tristate, then it would
be reasonable to select MFD_LS2K_BMC_CORE or depends on MFD_LS2K_BMC_CORE.


Regarding the fact that IPMI_LS2K is bool and it is not an independent
module but a part of ipmi_si, it comes into my mind that we may choose
to adjust the dependency from ipmi_si. That is to remove "select
MFD_LS2K_BMC_CORE" from IPMI_LS2K, and add "select MFD_LS2K_BMC_CORE
if IPMI_LS2K" to IPMI_SI.

I wonder if such a change would be appropriate.

Cheers,

Miao Wang

Re: [PATCH RFC v5 5/7] ipmi: ls2k: Relax the dependency to its mfd driver

[Corey Minyard]

On Tue, Aug 04, 2026 at 08:27:11PM +0800, Miao Wang wrote:
> Hi,
> 
> > 2026年8月4日 19:39，Corey Minyard <corey@minyard.net> 写道：
> > 
> > On Tue, Aug 04, 2026 at 05:40:14PM +0800, Miao Wang wrote:
> >> Hi,
> >> 
> >>> 2026年8月4日 04:46，Corey Minyard <corey@minyard.net> 写道：
> >>> 
> >>> On Tue, Aug 04, 2026 at 12:55:53AM +0800, Miao Wang via B4 Relay wrote:
> >>>> From: Miao Wang <shankerwangmiao@gmail.com>
> >>>> 
> >>>> There is no strong dependency between the IPMI driver and its mfd
> >>>> driver. Although the IPMI driver will not work without the mfd driver,
> >>>> it is not a hard dependency. The IPMI driver can actually be compiled
> >>>> without the mfd driver, and it will just fail to probe. When the mfd
> >>>> driver is loaded, the IPMI driver will probe successfully. Therefore,
> >>>> the dependency of the IPMI driver on its mfd driver should be relaxed
> >>>> to "imply" from "select". This will allow the mfd driver to be compiled
> >>>> as a module and the IPMI driver to be compiled as a part of the ipmi_si
> >>>> module. The adjustment to Kconfig for the mfd driver will be introduced
> >>>> in the later patch in this series.
> >>> 
> >>> I don't think that's what "imply" is for.  Imply seems to be for if
> >>> there is another subsystem that can use this subsystem, but doesn't
> >>> require it to exist.
> >>> 
> >>> For instance:
> >>> 
> >>> config SENSORS_NPCM7XX
> >>>       tristate "Nuvoton NPCM750 and compatible PWM and Fan controllers"
> >>>       imply THERMAL
> >>> 
> >>> The fan controller will work fine without the thermal subsystem; you
> >>> can control the fan speed without it.  But the thermal subsystem is the
> >>> logical user of this.  I looked at many of these things like this.
> >>> 
> >>> In the IPMI case, the IPMI driver is useless without the mfd part.  So
> >>> there's no point in compiling the IPMI part of this if the mfd part is
> >>> not there.
> >>> 
> >>> I could be wrong, but I can't see why you would want to do this.
> >> 
> >> The mfd part and the IPMI part loosely depend on each other. Without the
> >> IPMI part, the mfd part can still work to handle the display part.
> >> Without the mfd part, the IPMI part is indeed useless, but it will not
> >> generate compiling errors or other runtime errors. In the runtime,
> >> the IPMI part can be actually loaded earlier than the mfd part. As a
> >> result, their dependency is not that strong.
> > 
> > The operational dependency is strong, which is what I think you want to
> > convey here.
> > 
> >> 
> >> The reason why I want to change this is that "select" here requires the
> >> mfd part should also be compiled as built-in (i.e. = y), since the
> >> type of the configure entry IPMI_LS2K is bool. However, I cannot see
> >> there is no other reason preventing the mfd driver from compiling as
> >> a module. This patch series will introduce a minor fix, after which
> >> the mfd driver will be capable to be compiled as a module.
> >> 
> >> When the type of MFD_LS2K_BMC_CORE is changed to tristate, the "select"
> >> here will prevent selecting =m for MFD_LS2K_BMC_CORE. I thus believe
> >> that "select" here should be also changed.
> >> 
> >> Any suggestions on declaring the dependency of the both parts?
> > 
> > Ok, I understand now.
> > 
> > Why can't the IPMI part be compiled as a module?  Making that
> > module-capable would be the right fix, I think.  I can't see
> > why that wouldn't work.  IIRC, it was bool because the mfd part
> > was bool.
> 
> I would have agree with you if the IPMI part was a normal driver.
> However, the IPMI part is actually a part of ipmi_si. As a result,
> the IPMI part can actually be compiled as a module, but as a part
> of ipmi_si. That is why the configure entry IPMI_LS2K is bool rather
> than tristate. I don't think it is trivial to convert IPMI_LS2K from
> bool to tristate.

Yes, you are right it would be non-trivial.  It would take some redesign
of the ipmi_si module.  You are right here, probably not worth it.

> 
> > If you changed to imply, you would need a depends on the mfd core, BTW.
> 
> If imply is used here, and there is "select MFD_CORE" in MFD_LS2K_BMC_CORE,
> I think there is no need to add "depends on MFD_CORE" to IPMI_LS2K, if I
> understand it correctly.

If imply doesn't force MFD_LS2K_BMC_CORE to be selected, then it's not
going to force MFD_CORE to be selected.

> 
> I don't insist using imply here, if there is a better way to express the
> relation between both drivers.
> 
> > Also, IPMI_LS2K needs a "depends on IPMI_SI" either way.  I missed that
> > earlier.  Could you add that?
> 
> If I understand it correctly, there seems to be no need to add the
> dependency from the MFD driver to the driver for the actual sub-functions.
> Examples are:

There absolutely is.  You can select IPMI_LS2K without selecting
IPMI_SI.  It would compile without it, and it just wouldn't do anything,
but it would be confusing to be able to select something and it not do
anything.

> 
> - MFD_MENF21BMC and SENSORS_MENF21BMC_HWMON, LEDS_MENF21BMC, 
>   MENF21BMC_WATCHDOG: The later three declared depends on the former MFD
>   driver
> - MFD_INTEL_M10_BMC_CORE and FPGA_M10_BMC_SEC_UPDATE, 
>   SENSORS_INTEL_M10_BMC_HWMON: The later two declared depends on the
>   former MFD driver.
> - MFD_STMFX and PINCTRL_STMFX: The later declared select the former
>   MFD driver.
> 
> To summarize, as shown in the current mfd drivers, there is no need to
> declare dependency to the drivers providing the sub-functions in the
> mfd drivers, and the drivers of the sub functions should "depends on" or
> "select" the mfd driver. So if IPMI_LS2K could be tristate, then it would
> be reasonable to select MFD_LS2K_BMC_CORE or depends on MFD_LS2K_BMC_CORE.
> 
> 
> Regarding the fact that IPMI_LS2K is bool and it is not an independent
> module but a part of ipmi_si, it comes into my mind that we may choose
> to adjust the dependency from ipmi_si. That is to remove "select
> MFD_LS2K_BMC_CORE" from IPMI_LS2K, and add "select MFD_LS2K_BMC_CORE
> if IPMI_LS2K" to IPMI_SI.
> 
> I wonder if such a change would be appropriate.

That would be a good solution if it works.  Thanks for working with
me on this.

-corey

> 
> Cheers,
> 
> Miao Wang
>