[PATCH v3 0/3] Fix CS35L56 amplifier on Intel LPSS SPI with broken ACPI cs-gpios

[PATCH v3 0/3] Fix CS35L56 amplifier on Intel LPSS SPI with broken ACPI cs-gpios

[Khalil]

v3 of the patch series fixing dual CS35L56 amplifiers on HP laptops
with Intel Lunar Lake and broken ACPI cs-gpios.

Changes since v2:
- Rebased onto broonie/spi for-next (commit b00c00f7dc)
- No code changes

Changes since RFC v1 (addressing feedback from Richard Fitzgerald):
- Added DMI quirk table: GPIO CS fixup is now only applied on known
  affected platforms (HP EliteBook 8 G1i, board 8D8A), not generically
  for all devices with CS > 0.
- Fixed chip select range check: only chip selects outside the
  controller's num_chipselect range are fixed up. A NULL cs_gpiods[cs]
  within range means "native chip select", not broken.
- Removed ASUS reference (GU605C was fixed by BIOS update).
- Added Patch 1/3 (spi core): __spi_add_device() now preserves preset
  cs_gpiod on the device instead of unconditionally overwriting from
  ctlr->cs_gpiods. Suggested by Richard Fitzgerald.
- Patch 2/3 (serial-multi-instantiate): Extracted GPIO fixup into a
  dedicated helper function with DMI-based quirk table.
- Patch 3/3 (spi-pxa2xx): Handles clock gating on Intel LPSS
  controllers when GPIO chip select is active.

Tested on HP EliteBook 8 G1i 16 inch (Intel Core Ultra 7 258V,
Lunar Lake-M) with 2x CS35L56 Rev B0. Both amplifiers probe
successfully, load calibration and tuning, and produce audio.

Related bug reports:
- https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/2131138
- https://bugzilla.kernel.org/show_bug.cgi?id=221064
- https://github.com/thesofproject/linux/issues/5621

Khalil (3):
  spi: Preserve preset cs_gpiod in __spi_add_device()
  platform/x86: serial-multi-instantiate: Fix SPI chip select on
    platforms with incomplete ACPI cs-gpios
  spi: pxa2xx: Handle clock gating for GPIO chip select devices

 .../platform/x86/serial-multi-instantiate.c   | 168 ++++++++++++++++++
 drivers/spi/spi-pxa2xx.c                      |  45 ++++-
 drivers/spi/spi.c                             |   3 +-
 3 files changed, 211 insertions(+), 5 deletions(-)

-- 
2.43.0

[PATCH v3 1/3] spi: Preserve preset cs_gpiod in __spi_add_device()

[Khalil]

__spi_add_device() unconditionally overwrites spi->cs_gpiod[] from
ctlr->cs_gpiods[cs], even if the caller has already set a GPIO
descriptor on the device. This prevents drivers like
serial-multi-instantiate from pre-configuring a GPIO chip select
acquired from ACPI before adding the device.

Skip the overwrite when the device already has a cs_gpiod set for
the given index, allowing callers to preset GPIO chip selects that
aren't described in the controller's cs-gpios property.

This is useful on platforms where the ACPI _DSD cs-gpios property
on the SPI controller is incomplete, but the peripheral's ACPI node
does contain the correct GpioIo resource for its chip select.

Suggested-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Signed-off-by: Khalil <khalilst@gmail.com>
---
 drivers/spi/spi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 07c572e1df..fbfb9a1aa2 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -924,7 +924,8 @@ static int __spi_add_device(struct spi_device *spi, struct spi_device *parent)
 	if (ctlr->cs_gpiods) {
 		for (idx = 0; idx < spi->num_chipselect; idx++) {
 			cs = spi_get_chipselect(spi, idx);
-			spi_set_csgpiod(spi, idx, ctlr->cs_gpiods[cs]);
+			if (!spi_get_csgpiod(spi, idx))
+				spi_set_csgpiod(spi, idx, ctlr->cs_gpiods[cs]);
 		}
 	}
 
-- 
2.43.0

[PATCH v3 2/3] platform/x86: serial-multi-instantiate: Fix SPI chip select on platforms with incomplete ACPI cs-gpios

[Khalil]

Some HP laptops with Intel Lunar Lake and dual Cirrus Logic CS35L56
amplifiers over SPI have an incomplete cs-gpios property in the SPI
controller's _DSD - it only declares the first chip select. The
remaining chip select GPIOs are defined as GpioIo resources in the
peripheral's ACPI node but are not referenced by the controller.

This causes the SPI framework to reject devices whose chip select
exceeds num_chipselect with -EINVAL, preventing the second amplifier
from probing.

Fix this on known affected platforms by:

1. Adding a DMI quirk table to identify affected systems
2. For devices with chip selects outside the controller's range,
   acquiring the GPIO from the peripheral's ACPI GpioIo resource
3. Extending num_chipselect and reallocating the controller's
   cs_gpiods array to install the GPIO descriptor
4. Setting SPI_CONTROLLER_GPIO_SS so the framework calls both
   the GPIO toggle and controller->set_cs (needed for clock
   gating on Intel LPSS controllers)

Only chip selects beyond the controller's num_chipselect are fixed up.
Chip selects within range with a NULL cs_gpiods entry are left alone,
as NULL means "native chip select" which is intentional.

Tested on HP EliteBook 8 G1i 16 inch (board 8D8A) with 2x CS35L56
Rev B0 amplifiers. Both amplifiers probe and produce audio.

Signed-off-by: Khalil <khalilst@gmail.com>
---
 .../platform/x86/serial-multi-instantiate.c   | 168 ++++++++++++++++++
 1 file changed, 168 insertions(+)

diff --git a/drivers/platform/x86/serial-multi-instantiate.c b/drivers/platform/x86/serial-multi-instantiate.c
index 1a369334f9..0d30bd0a7b 100644
--- a/drivers/platform/x86/serial-multi-instantiate.c
+++ b/drivers/platform/x86/serial-multi-instantiate.c
@@ -8,6 +8,10 @@
 
 #include <linux/acpi.h>
 #include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/dmi.h>
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/machine.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
@@ -46,6 +50,53 @@ struct smi {
 	int spi_num;
 	struct i2c_client **i2c_devs;
 	struct spi_device **spi_devs;
+	struct gpio_desc *cs_gpio;
+};
+
+/*
+ * Quirk data for platforms with broken ACPI SPI chip select descriptions.
+ * cs_gpio_idx: index of the GpioIo resource in the ACPI _CRS that provides
+ *              the chip select GPIO for devices missing a proper cs-gpios
+ *              entry on the SPI controller.
+ */
+struct smi_cs_gpio_quirk {
+	int cs_gpio_idx;
+};
+
+static const struct smi_cs_gpio_quirk hp_elitebook_8g1i_quirk = {
+	.cs_gpio_idx = 0,
+};
+
+/*
+ * DMI table of platforms with broken SPI chip select ACPI descriptions.
+ *
+ * These systems have multiple SPI peripherals (e.g., dual CS35L56
+ * amplifiers) but the SPI controller's _DSD cs-gpios property is
+ * incomplete - it only declares the first chip select. The remaining
+ * chip select GPIOs are defined as GpioIo resources in the peripheral's
+ * ACPI node but are not referenced by the controller.
+ */
+static const struct dmi_system_id smi_cs_gpio_dmi_table[] = {
+	{
+		.ident = "HP EliteBook 8 G1i 16 inch",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "HP"),
+			DMI_MATCH(DMI_BOARD_NAME, "8D8A"),
+		},
+		.driver_data = (void *)&hp_elitebook_8g1i_quirk,
+	},
+	{ }
+};
+
+/*
+ * ACPI GPIO mapping for the chip select GpioIo resource.
+ * Maps "cs-gpios" to the GpioIo resource at index 0 of the ACPI _CRS.
+ */
+static const struct acpi_gpio_params smi_cs_gpio_params = { 0, 0, false };
+
+static const struct acpi_gpio_mapping smi_cs_gpio_mapping[] = {
+	{ "cs-gpios", &smi_cs_gpio_params, 1 },
+	{ }
 };
 
 static int smi_get_irq(struct platform_device *pdev, struct acpi_device *adev,
@@ -99,6 +150,101 @@ static void smi_devs_unregister(struct smi *smi)
 	}
 }
 
+/*
+ * smi_spi_setup_cs_gpio - Fix up chip select for a device on a platform
+ * with broken ACPI cs-gpios description.
+ *
+ * On affected platforms, the SPI controller's cs-gpios property is incomplete,
+ * so the framework has no GPIO descriptor for some chip selects. This causes
+ * __spi_add_device() to reject the device with -EINVAL (cs >= num_chipselect).
+ *
+ * This function:
+ * 1. Extends num_chipselect if the device's CS is out of range
+ * 2. Reallocates cs_gpiods to match, preventing out-of-bounds access
+ *    in __spi_add_device()
+ * 3. Installs the GPIO from the peripheral's ACPI node into the
+ *    controller's cs_gpiods array so __spi_add_device() propagates
+ *    it to the device
+ * 4. Sets SPI_CONTROLLER_GPIO_SS so the framework calls both the GPIO
+ *    toggle and controller->set_cs (needed for clock gating on Intel
+ *    LPSS controllers)
+ */
+static int smi_spi_setup_cs_gpio(struct device *dev,
+				 struct spi_device *spi_dev,
+				 struct smi *smi,
+				 const struct smi_cs_gpio_quirk *quirk)
+{
+	struct spi_controller *ctlr = spi_dev->controller;
+	struct gpio_desc **new_gpiods;
+	u16 cs = spi_get_chipselect(spi_dev, 0);
+
+	/*
+	 * Only fix up chip selects that the controller doesn't know about.
+	 * A NULL cs_gpiods[cs] within the controller's num_chipselect range
+	 * means "native chip select" - that's intentional, not broken.
+	 * The broken case is when cs >= num_chipselect, meaning the ACPI
+	 * cs-gpios property on the controller was incomplete.
+	 */
+	if (cs < ctlr->num_chipselect)
+		return 0;
+
+	/* Extend num_chipselect to cover this device */
+	dev_info(dev, "Extending num_chipselect from %u to %u for CS%u\n",
+		 ctlr->num_chipselect, cs + 1, cs);
+	ctlr->num_chipselect = cs + 1;
+
+	/* Acquire the CS GPIO from the ACPI GpioIo resource if not yet done */
+	if (!smi->cs_gpio) {
+		int ret;
+
+		ret = devm_acpi_dev_add_driver_gpios(dev, smi_cs_gpio_mapping);
+		if (ret) {
+			dev_warn(dev, "Failed to add CS GPIO mapping: %d\n", ret);
+			return ret;
+		}
+
+		smi->cs_gpio = devm_gpiod_get(dev, "cs", GPIOD_OUT_HIGH);
+		if (IS_ERR(smi->cs_gpio)) {
+			dev_warn(dev, "Failed to get CS GPIO: %ld\n",
+				 PTR_ERR(smi->cs_gpio));
+			smi->cs_gpio = NULL;
+			return -ENOENT;
+		}
+		dev_info(dev, "Acquired CS GPIO for CS%u from ACPI GpioIo[%d]\n",
+			 cs, quirk->cs_gpio_idx);
+	}
+
+	/*
+	 * Reallocate the controller's cs_gpiods array to accommodate the
+	 * new num_chipselect, and install the GPIO descriptor. This is
+	 * necessary because __spi_add_device() unconditionally reads
+	 * ctlr->cs_gpiods[cs] to set the device's cs_gpiod.
+	 */
+	new_gpiods = devm_kcalloc(&ctlr->dev, ctlr->num_chipselect,
+				  sizeof(*new_gpiods), GFP_KERNEL);
+	if (!new_gpiods)
+		return -ENOMEM;
+
+	if (ctlr->cs_gpiods) {
+		unsigned int i;
+
+		for (i = 0; i < cs; i++)
+			new_gpiods[i] = ctlr->cs_gpiods[i];
+	}
+	new_gpiods[cs] = smi->cs_gpio;
+	ctlr->cs_gpiods = new_gpiods;
+
+	/*
+	 * SPI_CONTROLLER_GPIO_SS ensures the framework calls both the
+	 * GPIO CS toggle and controller->set_cs(). This is required on
+	 * Intel LPSS controllers where set_cs handles clock gating.
+	 */
+	ctlr->flags |= SPI_CONTROLLER_GPIO_SS;
+
+	dev_info(dev, "Installed GPIO CS on controller for CS%u\n", cs);
+	return 0;
+}
+
 /**
  * smi_spi_probe - Instantiate multiple SPI devices from inst array
  * @pdev:	Platform device
@@ -112,10 +258,19 @@ static int smi_spi_probe(struct platform_device *pdev, struct smi *smi,
 {
 	struct device *dev = &pdev->dev;
 	struct acpi_device *adev = ACPI_COMPANION(dev);
+	const struct dmi_system_id *dmi_id;
+	const struct smi_cs_gpio_quirk *quirk = NULL;
 	struct spi_controller *ctlr;
 	struct spi_device *spi_dev;
 	char name[50];
 	int i, ret, count;
+	u16 cs;
+
+	dmi_id = dmi_first_match(smi_cs_gpio_dmi_table);
+	if (dmi_id) {
+		quirk = dmi_id->driver_data;
+		dev_info(dev, "Applying CS GPIO quirk for %s\n", dmi_id->ident);
+	}
 
 	ret = acpi_spi_count_resources(adev);
 	if (ret < 0)
@@ -139,6 +294,19 @@ static int smi_spi_probe(struct platform_device *pdev, struct smi *smi,
 		}
 
 		ctlr = spi_dev->controller;
+		cs = spi_get_chipselect(spi_dev, 0);
+
+		/*
+		 * On quirked platforms, fix up the chip select GPIO for
+		 * devices that would otherwise fail due to incomplete
+		 * ACPI cs-gpios on the SPI controller.
+		 */
+		if (quirk) {
+			ret = smi_spi_setup_cs_gpio(dev, spi_dev, smi, quirk);
+			if (ret)
+				dev_dbg(dev, "CS GPIO setup returned %d for CS%u\n",
+					ret, cs);
+		}
 
 		strscpy(spi_dev->modalias, inst_array[i].type);
 
-- 
2.43.0

[PATCH v3 3/3] spi: pxa2xx: Handle clock gating for GPIO chip select devices

[Khalil]

On Intel LPSS SPI controllers (Cannon Lake and later) with dynamic
clock gating (cs_clk_stays_gated=true), the SPI clock is gated when
no native chip select is asserted. When using a GPIO chip select
(via SPI_CONTROLLER_GPIO_SS), the SPI framework toggles the GPIO
and also calls the controller's set_cs callback.

Handle this in the pxa2xx cs_assert/cs_deassert functions: when the
device uses a GPIO chip select on an LPSS controller, assert native
CS in the control register to enable the clock, and force the clock
gate on. On deassert, restore both.

This is needed on platforms where serial-multi-instantiate installs
a GPIO chip select from the peripheral's ACPI GpioIo resource to
work around an incomplete cs-gpios property on the SPI controller.

Signed-off-by: Khalil <khalilst@gmail.com>
---
 drivers/spi/spi-pxa2xx.c | 45 ++++++++++++++++++++++++++++++++++++----
 1 file changed, 41 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
index 6291d7c2e0..fe57620630 100644
--- a/drivers/spi/spi-pxa2xx.c
+++ b/drivers/spi/spi-pxa2xx.c
@@ -419,20 +419,43 @@ static void cs_assert(struct spi_device *spi)
 {
 	struct driver_data *drv_data =
 		spi_controller_get_devdata(spi->controller);
+	const struct lpss_config *config;
 
 	if (drv_data->ssp_type == CE4100_SSP) {
 		pxa2xx_spi_write(drv_data, SSSR, spi_get_chipselect(spi, 0));
 		return;
 	}
 
-	if (is_lpss_ssp(drv_data))
-		lpss_ssp_cs_control(spi, true);
+	if (is_lpss_ssp(drv_data)) {
+		config = lpss_get_config(drv_data);
+
+		if (spi_is_csgpiod(spi)) {
+			/*
+			 * GPIO handles the actual chip select to the device.
+			 * On LPSS controllers with dynamic clock gating, the
+			 * SPI clock won't run unless the native CS state says
+			 * "asserted" in the CS control register. Assert native
+			 * CS in the register to enable the clock, and force
+			 * the clock gate on.
+			 */
+			lpss_ssp_cs_control(spi, true);
+			if (config->cs_clk_stays_gated) {
+				__lpss_ssp_update_priv(drv_data,
+					LPSS_PRIV_CLOCK_GATE,
+					LPSS_PRIV_CLOCK_GATE_CLK_CTL_MASK,
+					LPSS_PRIV_CLOCK_GATE_CLK_CTL_FORCE_ON);
+			}
+		} else {
+			lpss_ssp_cs_control(spi, true);
+		}
+	}
 }
 
 static void cs_deassert(struct spi_device *spi)
 {
 	struct driver_data *drv_data =
 		spi_controller_get_devdata(spi->controller);
+	const struct lpss_config *config;
 	unsigned long timeout;
 
 	if (drv_data->ssp_type == CE4100_SSP)
@@ -444,8 +467,22 @@ static void cs_deassert(struct spi_device *spi)
 	       !time_after(jiffies, timeout))
 		cpu_relax();
 
-	if (is_lpss_ssp(drv_data))
-		lpss_ssp_cs_control(spi, false);
+	if (is_lpss_ssp(drv_data)) {
+		config = lpss_get_config(drv_data);
+
+		if (spi_is_csgpiod(spi)) {
+			/* Deassert native CS and restore clock gating */
+			lpss_ssp_cs_control(spi, false);
+			if (config->cs_clk_stays_gated) {
+				__lpss_ssp_update_priv(drv_data,
+					LPSS_PRIV_CLOCK_GATE,
+					LPSS_PRIV_CLOCK_GATE_CLK_CTL_MASK,
+					LPSS_PRIV_CLOCK_GATE_CLK_CTL_FORCE_OFF);
+			}
+		} else {
+			lpss_ssp_cs_control(spi, false);
+		}
+	}
 }
 
 static void pxa2xx_spi_set_cs(struct spi_device *spi, bool level)
-- 
2.43.0

Re: [PATCH v3 0/3] Fix CS35L56 amplifier on Intel LPSS SPI with broken ACPI cs-gpios

[Richard Fitzgerald]

On 01/09/2026 8:26 pm, Khalil wrote:
> v3 of the patch series fixing dual CS35L56 amplifiers on HP laptops
> with Intel Lunar Lake and broken ACPI cs-gpios.

HP told us they have a BIOS with the cs-gpios fixed, and they can make
that available early if you post a support request for it.

Can you test that new BIOS? It would avoid the messy SPI workarounds.