[PATCH] mfd: mxs-lradc: Pass mapped IRQs to child devices

[PATCH] mfd: mxs-lradc: Pass mapped IRQs to child devices

[Fabio Estevam]

The MFD resource tables store indices into the parent DT interrupts
property. Since the MFD core is given neither an IRQ domain nor a base,
however, it exposes those indices to child devices as though they were
Linux IRQ numbers.

The touchscreen interrupt is at DT index 0 on both supported SoCs.
platform_get_irq_byname() therefore rejects its child resource with:

 0 is an invalid IRQ number

On current kernels it also returns -EINVAL, preventing the touchscreen
driver from probing.

The child drivers try to map their resource values afterwards with
irq_of_parse_and_map(), but the touchscreen driver never reaches that
call for index 0. More generally, translating the parent firmware's IRQ
indices does not belong in the child drivers, where platform IRQ
resources are expected to contain mapped Linux IRQs already.

Have the MFD parent copy each resource template and resolve its IRQ
indices with platform_get_irq() before registering the child. The child
drivers can then request the mapped IRQs directly. Use per-device copies
so later instances and reprobes still start with the DT indices.

Apply the same fix to the ADC child, which uses the same IRQ mapping
scheme.

Tested on an i.MX28 EVK. The mxs-lradc-ts driver now probes
successfully, and its interrupt counters increase when the screen is
touched.

Cc: stable@vger.kernel.org
Fixes: a85a6c86c25b ("driver core: platform: Clarify that IRQ 0 is invalid")
Closes: https://lore.kernel.org/linux-input/CAOMZO5CgTzo6GuXptD4mFTN=UsJJqpkixDW1Q64gqZGrij8+uQ@mail.gmail.com/
Signed-off-by: Fabio Estevam <festevam@gmail.com>
---
This is a long-standing bug that I reported in 2020:
https://lore.kernel.org/linux-input/CAOMZO5CgTzo6GuXptD4mFTN=UsJJqpkixDW1Q64gqZGrij8+uQ@mail.gmail.com/

This patch touches MFD, IIO, and Input. Since the IRQ mapping is moved
into the MFD parent, I suggest merging it through the MFD tree, with
acks from the IIO and Input maintainers.

The full backtrace:

[   10.540505] WARNING: drivers/base/platform.c:492 at __platform_get_irq_byname+0xb4/0xcc, CPU#0: swapper/0/1
[   10.555516] 0 is an invalid IRQ number
[   10.559627] Modules linked in:
[   10.562849] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 7.3.0-rc7-next-20261016-00003-g36062817a968 #17 VOLUNTARY
[   10.573732] Hardware name: Freescale MXS (Device Tree)
[   10.578934] Call trace:
[   10.578992]  unwind_backtrace from show_stack+0x10/0x14
[   10.586955]  show_stack from dump_stack_lvl+0x48/0x64
[   10.592170]  dump_stack_lvl from __warn+0x8c/0x190
[   10.597114]  __warn from warn_slowpath_fmt+0x94/0xcc
[   10.602232]  warn_slowpath_fmt from __platform_get_irq_byname+0xb4/0xcc
[   10.609027]  __platform_get_irq_byname from platform_get_irq_byname+0x10/0x30
[   10.616337]  platform_get_irq_byname from mxs_lradc_ts_probe+0x18c/0x378
[   10.623247]  mxs_lradc_ts_probe from platform_probe+0x58/0x90
[   10.629174]  platform_probe from really_probe+0xc4/0x2cc
[   10.634649]  really_probe from __driver_probe_device+0xa0/0x1e0
[   10.640721]  __driver_probe_device from driver_probe_device+0x30/0xc0
[   10.647315]  driver_probe_device from __driver_attach+0x94/0x158
[   10.653466]  __driver_attach from bus_for_each_dev+0x7c/0xd0
[   10.659280]  bus_for_each_dev from bus_add_driver+0x158/0x1fc
[   10.665169]  bus_add_driver from driver_register+0x7c/0x114
[   10.670901]  driver_register from do_one_initcall+0x60/0x294
[   10.676721]  do_one_initcall from kernel_init_freeable+0x19c/0x24c
[   10.683073]  kernel_init_freeable from kernel_init+0x14/0x10c
[   10.688997]  kernel_init from ret_from_fork+0x14/0x38
[   10.694200] Exception stack(0xc8819fb0 to 0xc8819ff8)
[   10.699335] 9fa0:                                     00000000 00000000 00000000 00000000
[   10.707591] 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[   10.715843] 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000
[   10.723117] irq event stamp: 146363
[   10.726729] hardirqs last  enabled at (146367): [<c00adbd8>] __nbcon_atomic_flush_pending_con+0x120/0x1c0
[   10.736770] hardirqs last disabled at (146372): [<c0008f38>] __irq_svc+0x58/0xb0
[   10.744618] softirqs last  enabled at (146362): [<c0032c20>] __irq_exit_rcu+0x148/0x1d4
[   10.753153] softirqs last disabled at (146385): [<c0032c20>] __irq_exit_rcu+0x148/0x1d4
[   10.761603] ---[ end trace 0000000000000000 ]---
[   10.766374] mxs-lradc-ts mxs-lradc-ts: error -EINVAL: IRQ mxs-lradc-touchscreen not found
[   10.766456] mxs-lradc-ts mxs-lradc-ts: probe with driver mxs-lradc-ts failed with error -22

 drivers/iio/adc/mxs-lradc-adc.c          |  7 +---
 drivers/input/touchscreen/mxs-lradc-ts.c |  7 +---
 drivers/mfd/mxs-lradc.c                  | 47 +++++++++++++++++++-----
 3 files changed, 42 insertions(+), 19 deletions(-)

diff --git a/drivers/iio/adc/mxs-lradc-adc.c b/drivers/iio/adc/mxs-lradc-adc.c
index dda5182a5076..2c7129cd9c05 100644
--- a/drivers/iio/adc/mxs-lradc-adc.c
+++ b/drivers/iio/adc/mxs-lradc-adc.c
@@ -17,7 +17,6 @@
 #include <linux/mfd/core.h>
 #include <linux/mfd/mxs-lradc.h>
 #include <linux/module.h>
-#include <linux/of_irq.h>
 #include <linux/platform_device.h>
 #include <linux/sysfs.h>
 
@@ -691,7 +690,7 @@ static int mxs_lradc_adc_probe(struct platform_device *pdev)
 	struct mxs_lradc_adc *adc;
 	struct iio_dev *iio;
 	struct resource *iores;
-	int ret, irq, virq, i, s, n;
+	int ret, irq, i, s, n;
 	u64 scale_uv;
 	const char **irq_name;
 
@@ -743,9 +742,7 @@ static int mxs_lradc_adc_probe(struct platform_device *pdev)
 		if (irq < 0)
 			return irq;
 
-		virq = irq_of_parse_and_map(dev->parent->of_node, irq);
-
-		ret = devm_request_irq(dev, virq, mxs_lradc_adc_handle_irq,
+		ret = devm_request_irq(dev, irq, mxs_lradc_adc_handle_irq,
 				       0, irq_name[i], iio);
 		if (ret)
 			return ret;
diff --git a/drivers/input/touchscreen/mxs-lradc-ts.c b/drivers/input/touchscreen/mxs-lradc-ts.c
index 137ab3b60f2d..ff9310592ad0 100644
--- a/drivers/input/touchscreen/mxs-lradc-ts.c
+++ b/drivers/input/touchscreen/mxs-lradc-ts.c
@@ -18,7 +18,6 @@
 #include <linux/mfd/core.h>
 #include <linux/mfd/mxs-lradc.h>
 #include <linux/of.h>
-#include <linux/of_irq.h>
 #include <linux/platform_device.h>
 
 static const char * const mxs_lradc_ts_irq_names[] = {
@@ -605,7 +604,7 @@ static int mxs_lradc_ts_probe(struct platform_device *pdev)
 	struct device_node *node = dev->parent->of_node;
 	struct mxs_lradc *lradc = dev_get_drvdata(dev->parent);
 	struct mxs_lradc_ts *ts;
-	int ret, irq, virq, i;
+	int ret, irq, i;
 	u32 ts_wires = 0, adapt;
 
 	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
@@ -674,11 +673,9 @@ static int mxs_lradc_ts_probe(struct platform_device *pdev)
 		if (irq < 0)
 			return irq;
 
-		virq = irq_of_parse_and_map(node, irq);
-
 		mxs_lradc_ts_stop(ts);
 
-		ret = devm_request_irq(dev, virq,
+		ret = devm_request_irq(dev, irq,
 				       mxs_lradc_ts_handle_irq,
 				       0, mxs_lradc_ts_irq_names[i], ts);
 		if (ret)
diff --git a/drivers/mfd/mxs-lradc.c b/drivers/mfd/mxs-lradc.c
index 64afc7631790..f893312a1d9b 100644
--- a/drivers/mfd/mxs-lradc.c
+++ b/drivers/mfd/mxs-lradc.c
@@ -22,7 +22,6 @@
 
 #define ADC_CELL		0
 #define TSC_CELL		1
-#define RES_MEM			0
 
 enum mx23_lradc_irqs {
 	MX23_LRADC_TS_IRQ = 0,
@@ -123,6 +122,42 @@ static const struct of_device_id mxs_lradc_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, mxs_lradc_dt_ids);
 
+static int mxs_lradc_add_device(struct platform_device *pdev,
+				struct mfd_cell *cell,
+				const struct resource *mem)
+{
+	struct resource *resources;
+	struct mfd_cell child = *cell;
+	int i, irq;
+
+	resources = devm_kmemdup_array(&pdev->dev, cell->resources,
+				       cell->num_resources,
+				       sizeof(*resources), GFP_KERNEL);
+	if (!resources)
+		return -ENOMEM;
+
+	for (i = 0; i < cell->num_resources; i++) {
+		if (resource_type(&resources[i]) == IORESOURCE_MEM) {
+			resources[i] = *mem;
+			continue;
+		}
+
+		if (resource_type(&resources[i]) != IORESOURCE_IRQ)
+			continue;
+
+		irq = platform_get_irq(pdev, resources[i].start);
+		if (irq < 0)
+			return irq;
+
+		resources[i].start = irq;
+		resources[i].end = irq;
+	}
+
+	child.resources = resources;
+	return devm_mfd_add_devices(&pdev->dev, PLATFORM_DEVID_NONE,
+				    &child, 1, NULL, 0, NULL);
+}
+
 static int mxs_lradc_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -189,13 +224,9 @@ static int mxs_lradc_probe(struct platform_device *pdev)
 
 	switch (lradc->soc) {
 	case IMX23_LRADC:
-		mx23_adc_resources[RES_MEM] = *res;
-		mx23_touchscreen_resources[RES_MEM] = *res;
 		cells = mx23_cells;
 		break;
 	case IMX28_LRADC:
-		mx28_adc_resources[RES_MEM] = *res;
-		mx28_touchscreen_resources[RES_MEM] = *res;
 		cells = mx28_cells;
 		break;
 	default:
@@ -204,8 +235,7 @@ static int mxs_lradc_probe(struct platform_device *pdev)
 		goto err_clk;
 	}
 
-	ret = devm_mfd_add_devices(&pdev->dev, PLATFORM_DEVID_NONE,
-				   &cells[ADC_CELL], 1, NULL, 0, NULL);
+	ret = mxs_lradc_add_device(pdev, &cells[ADC_CELL], res);
 	if (ret) {
 		dev_err(&pdev->dev, "Failed to add the ADC subdevice\n");
 		goto err_clk;
@@ -214,8 +244,7 @@ static int mxs_lradc_probe(struct platform_device *pdev)
 	if (!lradc->touchscreen_wire)
 		return 0;
 
-	ret = devm_mfd_add_devices(&pdev->dev, PLATFORM_DEVID_NONE,
-				   &cells[TSC_CELL], 1, NULL, 0, NULL);
+	ret = mxs_lradc_add_device(pdev, &cells[TSC_CELL], res);
 	if (ret) {
 		dev_err(&pdev->dev,
 			"Failed to add the touchscreen subdevice\n");
-- 
2.43.0

Re: [PATCH] mfd: mxs-lradc: Pass mapped IRQs to child devices

[Dmitry Torokhov]

On Sat, Oct 17, 2026 at 11:24:00PM -0300, Fabio Estevam wrote:
> The MFD resource tables store indices into the parent DT interrupts
> property. Since the MFD core is given neither an IRQ domain nor a base,
> however, it exposes those indices to child devices as though they were
> Linux IRQ numbers.
> 
> The touchscreen interrupt is at DT index 0 on both supported SoCs.
> platform_get_irq_byname() therefore rejects its child resource with:
> 
>  0 is an invalid IRQ number
> 
> On current kernels it also returns -EINVAL, preventing the touchscreen
> driver from probing.
> 
> The child drivers try to map their resource values afterwards with
> irq_of_parse_and_map(), but the touchscreen driver never reaches that
> call for index 0. More generally, translating the parent firmware's IRQ
> indices does not belong in the child drivers, where platform IRQ
> resources are expected to contain mapped Linux IRQs already.
> 
> Have the MFD parent copy each resource template and resolve its IRQ
> indices with platform_get_irq() before registering the child. The child
> drivers can then request the mapped IRQs directly. Use per-device copies
> so later instances and reprobes still start with the DT indices.
> 
> Apply the same fix to the ADC child, which uses the same IRQ mapping
> scheme.
> 
> Tested on an i.MX28 EVK. The mxs-lradc-ts driver now probes
> successfully, and its interrupt counters increase when the screen is
> touched.
> 
> Cc: stable@vger.kernel.org
> Fixes: a85a6c86c25b ("driver core: platform: Clarify that IRQ 0 is invalid")
> Closes: https://lore.kernel.org/linux-input/CAOMZO5CgTzo6GuXptD4mFTN=UsJJqpkixDW1Q64gqZGrij8+uQ@mail.gmail.com/
> Signed-off-by: Fabio Estevam <festevam@gmail.com>
> ---
> This is a long-standing bug that I reported in 2020:
> https://lore.kernel.org/linux-input/CAOMZO5CgTzo6GuXptD4mFTN=UsJJqpkixDW1Q64gqZGrij8+uQ@mail.gmail.com/
> 
> This patch touches MFD, IIO, and Input. Since the IRQ mapping is moved
> into the MFD parent, I suggest merging it through the MFD tree, with
> acks from the IIO and Input maintainers.

Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> # for input

Thanks.

-- 
Dmitry