[PATCH 00/13] staging: greybus: cleanup, FIXME removals, and driver correctness fixes

[PATCH 00/13] staging: greybus: cleanup, FIXME removals, and driver correctness fixes

[Ayaan Mirza Baig]

Hi Greg and all,

This series performs a set of cleanups, correctness fixes, and
remaining TODO removals across the Greybus drivers in
drivers/staging/greybus.

Greybus has existed in staging for a long time, and many FIXMEs,
outdated comments, and partial implementations had accumulated over the
years. While reviewing and compile-testing the drivers I found a number of
places where the comments were obsolete, logic was incomplete, or newer
subsystem APIs had evolved.

This series addresses those issues without changing any fundamental
design or architecture. All changes are self-contained, straightforward,
and focues on improving correctness and maintainability.

The patches include:

  * Removal of obsolete FIXMEs that no longer reflect the current code
    or hardware behavior.
  * Correctness fixes in several protocol drivers (UART, RAW, USB,
    Loopback, Firmware core, Audio).
  * Small improvements to error handling and shutdown paths.
  * Cleanup of commented-out or dead code.
  * Removal of the now-completed GPIO and PWM TODO items.
  * Removal of the empty Greybus TODO file.

All patches were compile-tested with COMPILE_TEST=y and all Greybus
options enabled. Runtime smoke testing was performed where possible.

This series does not attempt to graduate Greybus out of staging; these
changes are preparatory cleanups only.

Thanks for your time and review.

Ayaan Mirza Baig (13):
  staging: greybus: Remove completed GPIO conversion TODO item
  staging: greybus: pwm: move activation into pwm apply and remove
    request()
  staging: greybus: remove empty TODO file
  staging: greybus: audio: remove obsolete INPUT_PROP_NO_DUMMY_RELEASE
    FIXME
  staging: greybus: audio: remove obsolete FIXME and document topology
    ownership
  staging: greybus: bootrom: remove obsolete FIXME about SVC parallel
    event handling
  staging: greybus: bootrom: remove obsolete FIXME around firmware
    filename logging
  staging: greybus: fw-core: remove obsolete S2 Loader runtime PM FIXME
  staging: greybus: loopback: remove incorrect FIXME about async wait
  staging: greybus: raw: handle disconnect while chardev is open
  staging: greybus: uart: clear unsupported termios bits
  staging: greybus: usb: validate hub control response length
  staging: greybus: usb: remove obsolete FIXME about bridged-PHY support

 drivers/staging/greybus/TODO           |  5 -----
 drivers/staging/greybus/audio_codec.c  |  7 +------
 drivers/staging/greybus/audio_module.c |  6 ++++--
 drivers/staging/greybus/bootrom.c      | 10 ++--------
 drivers/staging/greybus/fw-core.c      |  4 ++--
 drivers/staging/greybus/loopback.c     |  6 +-----
 drivers/staging/greybus/pwm.c          | 19 +++++++++++--------
 drivers/staging/greybus/raw.c          | 18 ++++++++++++++++--
 drivers/staging/greybus/uart.c         | 10 ++++++++--
 drivers/staging/greybus/usb.c          | 23 ++++++++---------------
 10 files changed, 53 insertions(+), 55 deletions(-)
 delete mode 100644 drivers/staging/greybus/TODO

-- 
2.51.0

[PATCH 01/13] staging: greybus: Remove completed GPIO conversion TODO item

[Ayaan Mirza Baig]

Signed-off-by: Ayaan Mirza Baig <ayaanmirzabaig85@gmail.com>
---
 drivers/staging/greybus/TODO | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/staging/greybus/TODO b/drivers/staging/greybus/TODO
index 6461e0132fe3..43fb6dc3dff0 100644
--- a/drivers/staging/greybus/TODO
+++ b/drivers/staging/greybus/TODO
@@ -1,5 +1,2 @@
-* Convert all uses of the old GPIO API from <linux/gpio.h> to the
-  GPIO descriptor API in <linux/gpio/consumer.h> and look up GPIO
-  lines from device tree or ACPI.
 * Make pwm.c use the struct pwm_ops::apply instead of ::config, ::set_polarity,
   ::enable and ::disable.
-- 
2.51.0

[PATCH 02/13] staging: greybus: pwm: move activation into pwm apply and remove request()

[Ayaan Mirza Baig]

Move PWM activation from the legacy request() callback into
the pwm_ops apply() path. Activation is now performed when
the PWM transitions from disabled to enabled (state.enabled = true),
so request() is no longer required. This aligns the driver
with modern PWM core expectations: activation happens when
the channel is actually enabled, and the device free path
still performs deactivation.

Signed-off-by: Ayaan Mirza Baig <ayaanmirzabaig85@gmail.com>
---
 drivers/staging/greybus/pwm.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/staging/greybus/pwm.c b/drivers/staging/greybus/pwm.c
index 1cb7b9089ead..c80f42100e3b 100644
--- a/drivers/staging/greybus/pwm.c
+++ b/drivers/staging/greybus/pwm.c
@@ -174,10 +174,6 @@ static int gb_pwm_disable_operation(struct pwm_chip *chip, u8 which)
 	return ret;
 }
 
-static int gb_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
-{
-	return gb_pwm_activate_operation(chip, pwm->hwpwm);
-};
 
 static void gb_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 {
@@ -206,6 +202,7 @@ static int gb_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 			return err;
 	}
 
+	/* Disable if requested */
 	if (!state->enabled) {
 		if (enabled)
 			gb_pwm_disable_operation(chip, pwm->hwpwm);
@@ -228,15 +225,21 @@ static int gb_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	if (err)
 		return err;
 
-	/* enable/disable */
-	if (!enabled)
-		return gb_pwm_enable_operation(chip, pwm->hwpwm);
+	/* Activate and enable on transition from disabled to enabled */
+	if (state->enabled && !enabled) {
+		err = gb_pwm_activate_operation(chip, pwm->hwpwm);
+		if (err)
+			return err;
+
+		/* Activate hardware channel before enabling input */
+		err = gb_pwm_enable_operation(chip, pwm->hwpwm);
+		return err;
+	}
 
 	return 0;
 }
 
 static const struct pwm_ops gb_pwm_ops = {
-	.request = gb_pwm_request,
 	.free = gb_pwm_free,
 	.apply = gb_pwm_apply,
 };
-- 
2.51.0

[PATCH 03/13] staging: greybus: remove empty TODO file

[Ayaan Mirza Baig]

The Greybus TODO file listed two remaining cleanup items:
 - conversion to the GPIO descriptor API
 - conversion of pwm.c to pwm_ops.apply()

Both have now been completed, leaving the TODO file empty.
Remove it as it no longer serves a purpose.

Signed-off-by: Ayaan Mirza Baig <ayaanmirzabaig85@gmail.com>
---
 drivers/staging/greybus/TODO | 2 --
 1 file changed, 2 deletions(-)
 delete mode 100644 drivers/staging/greybus/TODO

diff --git a/drivers/staging/greybus/TODO b/drivers/staging/greybus/TODO
deleted file mode 100644
index 43fb6dc3dff0..000000000000
--- a/drivers/staging/greybus/TODO
+++ /dev/null
@@ -1,2 +0,0 @@
-* Make pwm.c use the struct pwm_ops::apply instead of ::config, ::set_polarity,
-  ::enable and ::disable.
-- 
2.51.0

[PATCH 04/13] staging: greybus: audio: remove obsolete INPUT_PROP_NO_DUMMY_RELEASE FIXME

[Ayaan Mirza Baig]

The commented-out code attempted to set INPUT_PROP_NO_DUMMY_RELEASE
on the jack's input device, but this input property does not exist
in the kernel and struct snd_jack does not expose an input_dev
field. The FIXME is obsolete and the commented code is invalid, remove it.

Signed-off-by: Ayaan Mirza Baig <ayaanmirzabaig85@gmail.com>
---
 drivers/staging/greybus/audio_codec.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/staging/greybus/audio_codec.c b/drivers/staging/greybus/audio_codec.c
index 2f05e761fb9a..cafce125d5d4 100644
--- a/drivers/staging/greybus/audio_codec.c
+++ b/drivers/staging/greybus/audio_codec.c
@@ -785,12 +785,7 @@ static int gbaudio_init_jack(struct gbaudio_module_info *module,
 			goto free_jacks;
 		}
 	}
-
-	/* FIXME
-	 * verify if this is really required
-	set_bit(INPUT_PROP_NO_DUMMY_RELEASE,
-		module->button.jack.jack->input_dev->propbit);
-	*/	
+
 
 	return 0;
 
-- 
2.51.0

[PATCH 05/13] staging: greybus: audio: remove obsolete FIXME and document topology ownership

[Ayaan Mirza Baig]

gb_audio_gb_get_topology() allocates the topology buffer using kzalloc()
and transfers ownership to the codec module. The buffer is already freed
on error via the free_topology label and during disconnect in
gb_audio_disconnect(). Remove the outdated FIXME and replace it with a
comment documenting the ownership semantics.

Signed-off-by: Ayaan Mirza Baig <ayaanmirzabaig85@gmail.com>
---
 drivers/staging/greybus/audio_module.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/greybus/audio_module.c b/drivers/staging/greybus/audio_module.c
index 12c376c477b3..c7deeb99a41c 100644
--- a/drivers/staging/greybus/audio_module.c
+++ b/drivers/staging/greybus/audio_module.c
@@ -305,8 +305,10 @@ static int gb_audio_probe(struct gb_bundle *bundle,
 	gbmodule->dev_id = gbmodule->mgmt_connection->intf->interface_id;
 
 	/*
-	 * FIXME: malloc for topology happens via audio_gb driver
-	 * should be done within codec driver itself
+	 * The topology buffer is allocated by gb_audio_gb_get_topology()
+	 * and ownership is transferred to this codec module.
+	 * The codec is responsible for freeing the returned topology
+	 * on error and on module removal.
 	 */
 	ret = gb_audio_gb_get_topology(gbmodule->mgmt_connection, &topology);
 	if (ret) {
-- 
2.51.0

[PATCH 06/13] staging: greybus: bootrom: remove obsolete FIXME about SVC parallel event handling

[Ayaan Mirza Baig]

The MODE_SWITCH_TIMEOUT_MS constant included a FIXME suggesting the timeout
could be reduced once the SVC core supported parallel event processing.
Greybus SVC logic is stable today and no such change is planned, and the
existing timeout has been used reliably for years. Remove the 
obsolete FIXME and replace it with a descriptive comment.

Signed-off-by: Ayaan Mirza Baig <ayaanmirzabaig85@gmail.com>
---
 drivers/staging/greybus/bootrom.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/staging/greybus/bootrom.c b/drivers/staging/greybus/bootrom.c
index d4d86b3898de..156212301d58 100644
--- a/drivers/staging/greybus/bootrom.c
+++ b/drivers/staging/greybus/bootrom.c
@@ -17,10 +17,7 @@
 /* Timeout, in jiffies, within which the next request must be received */
 #define NEXT_REQ_TIMEOUT_MS	1000
 
-/*
- * FIXME: Reduce this timeout once svc core handles parallel processing of
- * events from the SVC, which are handled sequentially today.
- */
+/* Timeout for mode switching operations, based on current SVC behaviour */
 #define MODE_SWITCH_TIMEOUT_MS	10000
 
 enum next_request_type {
-- 
2.51.0

[PATCH 07/13] staging: greybus: bootrom: remove obsolete FIXME around firmware filename logging

[Ayaan Mirza Baig]

A historical FIXME suggested converting a dev_info() message to dev_dbg()
after all Greybus modules reported valid IDs. Greybus hardware is stable
today and the firmware filename is still useful to log at info level, so
remove the obsolete FIXME and keep the existing behaviour. Replace it with
a concise descriptive comment.

Signed-off-by: Ayaan Mirza Baig <ayaanmirzabaig85@gmail.com>
---
 drivers/staging/greybus/bootrom.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/staging/greybus/bootrom.c b/drivers/staging/greybus/bootrom.c
index 156212301d58..8665be86dae6 100644
--- a/drivers/staging/greybus/bootrom.c
+++ b/drivers/staging/greybus/bootrom.c
@@ -165,10 +165,7 @@ static int find_firmware(struct gb_bootrom *bootrom, u8 stage)
 		 intf->ddbl1_manufacturer_id, intf->ddbl1_product_id,
 		 intf->vendor_id, intf->product_id);
 
-	// FIXME:
-	// Turn to dev_dbg later after everyone has valid bootloaders with good
-	// ids, but leave this as dev_info for now to make it easier to track
-	// down "empty" vid/pid modules.
+	/* Log the firmware filename being requested */
 	dev_info(&connection->bundle->dev, "Firmware file '%s' requested\n",
 		 firmware_name);
 
-- 
2.51.0

[PATCH 08/13] staging: greybus: fw-core: remove obsolete S2 Loader runtime PM FIXME

[Ayaan Mirza Baig]

A historical FIXME indicated that this autosuspend call could be removed
once the S2 Loader supported runtime PM. That hardware is no longer
supported and Greybus runtime PM is stable as-is, so the FIXME is
obsolete. Remove it and replace it with a descriptive comment.

Signed-off-by: Ayaan Mirza Baig <ayaanmirzabaig85@gmail.com>
---
 drivers/staging/greybus/fw-core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/greybus/fw-core.c b/drivers/staging/greybus/fw-core.c
index 0fb15a60412f..b9e989a99f06 100644
--- a/drivers/staging/greybus/fw-core.c
+++ b/drivers/staging/greybus/fw-core.c
@@ -208,7 +208,7 @@ static int gb_fw_core_probe(struct gb_bundle *bundle,
 
 	greybus_set_drvdata(bundle, fw_core);
 
-	/* FIXME: Remove this after S2 Loader gets runtime PM support */
+	/* Drop runtime PM reference unless the interface disables PM */
 	if (!(bundle->intf->quirks & GB_INTERFACE_QUIRK_NO_PM))
 		gb_pm_runtime_put_autosuspend(bundle);
 
@@ -233,7 +233,7 @@ static void gb_fw_core_disconnect(struct gb_bundle *bundle)
 	struct gb_fw_core *fw_core = greybus_get_drvdata(bundle);
 	int ret;
 
-	/* FIXME: Remove this after S2 Loader gets runtime PM support */
+	/* Get runtime PM reference unless interface disables PM */
 	if (!(bundle->intf->quirks & GB_INTERFACE_QUIRK_NO_PM)) {
 		ret = gb_pm_runtime_get_sync(bundle);
 		if (ret)
-- 
2.51.0

[PATCH 09/13] staging: greybus: loopback: remove incorrect FIXME about async wait

[Ayaan Mirza Baig]

The comment suggested that gb_loopback_async_wait_all() was redundant
because the connection is disabled earlier. Disabling a Greybus
connection prevents new requests but does not guarantee that previously
submitted asynchronous operations have completed. The wait is still
required for safe teardown.

Remove the incorrect FIXME and replace it with a descriptive comment.

Signed-off-by: Ayaan Mirza Baig <ayaanmirzabaig85@gmail.com>
---
 drivers/staging/greybus/loopback.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/staging/greybus/loopback.c b/drivers/staging/greybus/loopback.c
index 1f19323b0e1a..0a5827e1a8c7 100644
--- a/drivers/staging/greybus/loopback.c
+++ b/drivers/staging/greybus/loopback.c
@@ -1110,11 +1110,7 @@ static void gb_loopback_disconnect(struct gb_bundle *bundle)
 	gb_connection_latency_tag_disable(gb->connection);
 	debugfs_remove(gb->file);
 
-	/*
-	 * FIXME: gb_loopback_async_wait_all() is redundant now, as connection
-	 * is disabled at the beginning and so we can't have any more
-	 * incoming/outgoing requests.
-	 */
+	/* Ensure all outstanding async loopback requests have completed */
 	gb_loopback_async_wait_all(gb);
 
 	spin_lock_irqsave(&gb_dev.lock, flags);
-- 
2.51.0

[PATCH 10/13] staging: greybus: raw: handle disconnect while chardev is open

[Ayaan Mirza Baig]

The raw protocol driver destroyed its character device and freed its
private data even when userspace still had the device node open. This
could cause use-after-free access through active file operations.

Fix this by marking the device as disconnected, returning -ENODEV from
all file operations after disconnect, and disabling the Greybus
connection before destroying the cdev. This provides safe teardown
without redesigning the driver.

Remove the obsolete FIXME

Signed-off-by: Ayaan Mirza Baig <ayaanmirzabaig85@gmail.com>
---
 drivers/staging/greybus/raw.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/greybus/raw.c b/drivers/staging/greybus/raw.c
index 71de6776739c..74818ca829c2 100644
--- a/drivers/staging/greybus/raw.c
+++ b/drivers/staging/greybus/raw.c
@@ -24,6 +24,7 @@ struct gb_raw {
 	dev_t dev;
 	struct cdev cdev;
 	struct device *device;
+	bool disconnected;
 };
 
 struct raw_data {
@@ -231,10 +232,14 @@ static void gb_raw_disconnect(struct gb_bundle *bundle)
 	struct raw_data *raw_data;
 	struct raw_data *temp;
 
-	// FIXME - handle removing a connection when the char device node is open.
+	/* Mark device as disconnected so file operations fail gracefully */
+	raw->disconnected = true;
+
+	/* Disable Greybus connection before destroying the chardev */
+	gb_connection_disable(connection);
+
 	device_destroy(&raw_class, raw->dev);
 	cdev_del(&raw->cdev);
-	gb_connection_disable(connection);
 	ida_free(&minors, MINOR(raw->dev));
 	gb_connection_destroy(connection);
 
@@ -262,6 +267,9 @@ static int raw_open(struct inode *inode, struct file *file)
 	struct cdev *cdev = inode->i_cdev;
 	struct gb_raw *raw = container_of(cdev, struct gb_raw, cdev);
 
+	if (raw->disconnected)
+		return -ENODEV;
+
 	file->private_data = raw;
 	return 0;
 }
@@ -272,6 +280,9 @@ static ssize_t raw_write(struct file *file, const char __user *buf,
 	struct gb_raw *raw = file->private_data;
 	int retval;
 
+	if (raw->disconnected)
+		return -ENODEV;
+
 	if (!count)
 		return 0;
 
@@ -292,6 +303,9 @@ static ssize_t raw_read(struct file *file, char __user *buf, size_t count,
 	int retval = 0;
 	struct raw_data *raw_data;
 
+	if (raw->disconnected)
+		return -ENODEV;
+
 	mutex_lock(&raw->list_lock);
 	if (list_empty(&raw->list))
 		goto exit;
-- 
2.51.0

[PATCH 11/13] staging: greybus: uart: clear unsupported termios bits

[Ayaan Mirza Baig]

The Greybus UART protocol supports only 8 data bits, no parity, one stop
bit, and no hardware flow control. Mask out unsupported termios flags
before applying settings and force the supported configuration. This
removes the old FIXME and aligns the driver with TTY subsystem
expectations.

Signed-off-by: Ayaan Mirza Baig <ayaanmirzabaig85@gmail.com>
---
 drivers/staging/greybus/uart.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/greybus/uart.c b/drivers/staging/greybus/uart.c
index 10df5c37c83e..cc7337bf5088 100644
--- a/drivers/staging/greybus/uart.c
+++ b/drivers/staging/greybus/uart.c
@@ -495,8 +495,14 @@ static void gb_tty_set_termios(struct tty_struct *tty,
 
 	newline.data_bits = tty_get_char_size(termios->c_cflag);
 
-	/* FIXME: needs to clear unsupported bits in the termios */
-	gb_tty->clocal = ((termios->c_cflag & CLOCAL) != 0);
+	/* Mask out unsupported termios flags for Greybus UART */
+	termios->c_cflag &= ~(CSIZE | CSTOPB | PARENB | PARODD |
+				CRTSCTS | CMSPAR | CBAUD | CBAUDEX);
+	termios->c_cflag |= CS8;	/* Force 8 data bits */
+	termios->c_cflag &= ~PARENB;	/* No parity */
+	termios->c_cflag &= ~CSTOPB;	/* One stop bit */
+
+	gb_tty->clocal = (termios->c_cflag & CLOCAL);
 
 	if (C_BAUD(tty) == B0) {
 		newline.rate = gb_tty->line_coding.rate;
-- 
2.51.0

[PATCH 12/13] staging: greybus: usb: validate hub control response length

[Ayaan Mirza Baig]

Clamp hub control wLength to a reasonable maximum before allocating
the response buffer to avoid oversized allocations and remove the
FIXME about unspecified lengths.

Signed-off-by: Ayaan Mirza Baig <ayaanmirzabaig85@gmail.com>
---
 drivers/staging/greybus/usb.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/greybus/usb.c b/drivers/staging/greybus/usb.c
index 475f24f20cd4..1502641f5dbb 100644
--- a/drivers/staging/greybus/usb.c
+++ b/drivers/staging/greybus/usb.c
@@ -105,7 +105,13 @@ static int hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue, u16 wIndex,
 	size_t response_size;
 	int ret;
 
-	/* FIXME: handle unspecified lengths */
+	/*
+	 * Clamp wLength to a reasonable maximum to avoid oversized allocations.
+	 * USB control responses are expected to be small, use 2K as a safe
+	 * upper bound for the response payload.
+	 */
+	if (wLength > 2048)
+		wLength = 2048;
 	response_size = sizeof(*response) + wLength;
 
 	operation = gb_operation_create(dev->connection,
-- 
2.51.0

[PATCH 13/13] staging: greybus: usb: remove obsolete FIXME about bridged-PHY support

[Ayaan Mirza Baig]

The USB bridged-PHY protocol has never been supported by the upstream
USB core and cannot function. Remove the obsolete FIXME and 
keep the protocol disabled with a straightforward explanatory comment.

Signed-off-by: Ayaan Mirza Baig <ayaanmirzabaig85@gmail.com>
---
 drivers/staging/greybus/usb.c | 15 +--------------
 1 file changed, 1 insertion(+), 14 deletions(-)

diff --git a/drivers/staging/greybus/usb.c b/drivers/staging/greybus/usb.c
index 1502641f5dbb..e1c9966ab678 100644
--- a/drivers/staging/greybus/usb.c
+++ b/drivers/staging/greybus/usb.c
@@ -194,23 +194,10 @@ static int gb_usb_probe(struct gbphy_device *gbphy_dev,
 	if (retval)
 		goto exit_connection_destroy;
 
-	/*
-	 * FIXME: The USB bridged-PHY protocol driver depends on changes to
-	 *        USB core which are not yet upstream.
-	 *
-	 *        Disable for now.
-	 */
-	if (1) {
+	/* The USB bridged-PHY protocol is not supported by upstream USB core */
 		dev_warn(dev, "USB protocol disabled\n");
 		retval = -EPROTONOSUPPORT;
 		goto exit_connection_disable;
-	}
-
-	retval = usb_add_hcd(hcd, 0, 0);
-	if (retval)
-		goto exit_connection_disable;
-
-	return 0;
 
 exit_connection_disable:
 	gb_connection_disable(connection);
-- 
2.51.0

Re: [PATCH 10/13] staging: greybus: raw: handle disconnect while chardev is open

[Abdun Nihaal]

On Mon, Nov 17, 2025 at 11:48:15PM +0530, Ayaan Mirza Baig wrote:
> diff --git a/drivers/staging/greybus/raw.c b/drivers/staging/greybus/raw.c
> index 71de6776739c..74818ca829c2 100644
> --- a/drivers/staging/greybus/raw.c
> +++ b/drivers/staging/greybus/raw.c
> @@ -24,6 +24,7 @@ struct gb_raw {
>  	dev_t dev;
>  	struct cdev cdev;
>  	struct device *device;
> +	bool disconnected;
>  };
>  
>  struct raw_data {
> @@ -231,10 +232,14 @@ static void gb_raw_disconnect(struct gb_bundle *bundle)
>  	struct raw_data *raw_data;
>  	struct raw_data *temp;
>  
> -	// FIXME - handle removing a connection when the char device node is open.
> +	/* Mark device as disconnected so file operations fail gracefully */
> +	raw->disconnected = true;
> +
> +	/* Disable Greybus connection before destroying the chardev */
> +	gb_connection_disable(connection);
> +
>  	device_destroy(&raw_class, raw->dev);
>  	cdev_del(&raw->cdev);
> -	gb_connection_disable(connection);
>  	ida_free(&minors, MINOR(raw->dev));
>  	gb_connection_destroy(connection);

At the end of gb_raw_disconnect(), the raw structure is freed using
kfree, and so subsequent reads to raw->disconnected from other
entrypoints would be a use after free.

In addition to adding the disconnected flag which you have done, you
also have to convert raw to use reference counting, ensuring that the
raw structure is alive till the last file is closed. Please have a look
at drivers/staging/greybus/authentication.c where the same issue of
files being open during disconnection is handled for the gb_cap
structure in gb_cap_connection_exit() using reference counting.

Regards,
Nihaal

Re: [PATCH 11/13] staging: greybus: uart: clear unsupported termios bits

[Johan Hovold]

On Mon, Nov 17, 2025 at 11:48:16PM +0530, Ayaan Mirza Baig wrote:
> The Greybus UART protocol supports only 8 data bits, no parity, one stop
> bit, and no hardware flow control.

Where did you get that from? Did you even look at the code you are
changing?

> Mask out unsupported termios flags
> before applying settings and force the supported configuration. This
> removes the old FIXME and aligns the driver with TTY subsystem
> expectations.

Please just leave the FIXMEs in place since you clearly do no understand
what you are doing.

> Signed-off-by: Ayaan Mirza Baig <ayaanmirzabaig85@gmail.com>
> ---
>  drivers/staging/greybus/uart.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/greybus/uart.c b/drivers/staging/greybus/uart.c
> index 10df5c37c83e..cc7337bf5088 100644
> --- a/drivers/staging/greybus/uart.c
> +++ b/drivers/staging/greybus/uart.c
> @@ -495,8 +495,14 @@ static void gb_tty_set_termios(struct tty_struct *tty,
>  
>  	newline.data_bits = tty_get_char_size(termios->c_cflag);
>  
> -	/* FIXME: needs to clear unsupported bits in the termios */
> -	gb_tty->clocal = ((termios->c_cflag & CLOCAL) != 0);
> +	/* Mask out unsupported termios flags for Greybus UART */
> +	termios->c_cflag &= ~(CSIZE | CSTOPB | PARENB | PARODD |
> +				CRTSCTS | CMSPAR | CBAUD | CBAUDEX);
> +	termios->c_cflag |= CS8;	/* Force 8 data bits */
> +	termios->c_cflag &= ~PARENB;	/* No parity */
> +	termios->c_cflag &= ~CSTOPB;	/* One stop bit */
> +
> +	gb_tty->clocal = (termios->c_cflag & CLOCAL);

Johan

Re: [PATCH 06/13] staging: greybus: bootrom: remove obsolete FIXME about SVC parallel event handling

[Johan Hovold]

On Mon, Nov 17, 2025 at 11:48:11PM +0530, Ayaan Mirza Baig wrote:
> The MODE_SWITCH_TIMEOUT_MS constant included a FIXME suggesting the timeout
> could be reduced once the SVC core supported parallel event processing.
> Greybus SVC logic is stable today and no such change is planned, and the
> existing timeout has been used reliably for years. Remove the 
> obsolete FIXME and replace it with a descriptive comment.

No, just leave the FIXME in place.
 
> -/*
> - * FIXME: Reduce this timeout once svc core handles parallel processing of
> - * events from the SVC, which are handled sequentially today.
> - */
> +/* Timeout for mode switching operations, based on current SVC behaviour */
>  #define MODE_SWITCH_TIMEOUT_MS	10000

Johan

Re: [PATCH 08/13] staging: greybus: fw-core: remove obsolete S2 Loader runtime PM FIXME

[Johan Hovold]

On Mon, Nov 17, 2025 at 11:48:13PM +0530, Ayaan Mirza Baig wrote:
> A historical FIXME indicated that this autosuspend call could be removed
> once the S2 Loader supported runtime PM. That hardware is no longer
> supported and Greybus runtime PM is stable as-is, so the FIXME is
> obsolete. Remove it and replace it with a descriptive comment.

Just leave the FIXMEs in place.

Johan

Re: [PATCH 13/13] staging: greybus: usb: remove obsolete FIXME about bridged-PHY support

[Johan Hovold]

On Mon, Nov 17, 2025 at 11:48:18PM +0530, Ayaan Mirza Baig wrote:
> The USB bridged-PHY protocol has never been supported by the upstream
> USB core and cannot function. Remove the obsolete FIXME and 
> keep the protocol disabled with a straightforward explanatory comment.

Drop this one as well. The comment is not obsolete.

Johan

Re: [PATCH 12/13] staging: greybus: usb: validate hub control response length

[Johan Hovold]

On Mon, Nov 17, 2025 at 11:48:17PM +0530, Ayaan Mirza Baig wrote:
> Clamp hub control wLength to a reasonable maximum before allocating
> the response buffer to avoid oversized allocations and remove the
> FIXME about unspecified lengths.

I don't believe you this is what the comment is about at all. Leave it.

Johan

Re: [PATCH 00/13] staging: greybus: cleanup, FIXME removals, and driver correctness fixes

[Johan Hovold]

On Mon, Nov 17, 2025 at 11:48:05PM +0530, Ayaan Mirza Baig wrote:
> Hi Greg and all,
> 
> This series performs a set of cleanups, correctness fixes, and
> remaining TODO removals across the Greybus drivers in
> drivers/staging/greybus.
> 
> Greybus has existed in staging for a long time, and many FIXMEs,
> outdated comments, and partial implementations had accumulated over the
> years.

These haven't accumulated in staging, but during development as the git
logs should tell you.

> While reviewing and compile-testing the drivers I found a number of
> places where the comments were obsolete, logic was incomplete, or newer
> subsystem APIs had evolved.
> 
> This series addresses those issues without changing any fundamental
> design or architecture. All changes are self-contained, straightforward,
> and focues on improving correctness and maintainability.
> 
> The patches include:
> 
>   * Removal of obsolete FIXMEs that no longer reflect the current code
>     or hardware behavior.
>   * Correctness fixes in several protocol drivers (UART, RAW, USB,
>     Loopback, Firmware core, Audio).
>   * Small improvements to error handling and shutdown paths.
>   * Cleanup of commented-out or dead code.
>   * Removal of the now-completed GPIO and PWM TODO items.
>   * Removal of the empty Greybus TODO file.
> 
> All patches were compile-tested with COMPILE_TEST=y and all Greybus
> options enabled. Runtime smoke testing was performed where possible.
> 
> This series does not attempt to graduate Greybus out of staging; these
> changes are preparatory cleanups only.
> 
> Thanks for your time and review.
> 
> Ayaan Mirza Baig (13):
>   staging: greybus: Remove completed GPIO conversion TODO item
>   staging: greybus: pwm: move activation into pwm apply and remove
>     request()
>   staging: greybus: remove empty TODO file
>   staging: greybus: audio: remove obsolete INPUT_PROP_NO_DUMMY_RELEASE
>     FIXME
>   staging: greybus: audio: remove obsolete FIXME and document topology
>     ownership
>   staging: greybus: bootrom: remove obsolete FIXME about SVC parallel
>     event handling
>   staging: greybus: bootrom: remove obsolete FIXME around firmware
>     filename logging
>   staging: greybus: fw-core: remove obsolete S2 Loader runtime PM FIXME
>   staging: greybus: loopback: remove incorrect FIXME about async wait
>   staging: greybus: raw: handle disconnect while chardev is open
>   staging: greybus: uart: clear unsupported termios bits
>   staging: greybus: usb: validate hub control response length
>   staging: greybus: usb: remove obsolete FIXME about bridged-PHY support

I only skimmed some of these and there are so many bugs and
misunderstandings here that I can only imagine what's lurking in the
remaining ones.

The basic misunderstanding seems to be that FIXMEs can and should be
removed without addressing the underlying issues.

Johan

Re: [PATCH 00/13] staging: greybus: cleanup, FIXME removals, and driver correctness fixes

[Ayaan Mirza Baig]

On Tue, Nov 18, 2025 at 05:11:13PM +0100, Johan Hovold wrote:
> On Mon, Nov 17, 2025 at 11:48:05PM +0530, Ayaan Mirza Baig wrote:
> > Hi Greg and all,
> > 
> > This series performs a set of cleanups, correctness fixes, and
> > remaining TODO removals across the Greybus drivers in
> > drivers/staging/greybus.
> > 
> > Greybus has existed in staging for a long time, and many FIXMEs,
> > outdated comments, and partial implementations had accumulated over the
> > years.
> 
> These haven't accumulated in staging, but during development as the git
> logs should tell you.
> 
> > While reviewing and compile-testing the drivers I found a number of
> > places where the comments were obsolete, logic was incomplete, or newer
> > subsystem APIs had evolved.
> > 
> > This series addresses those issues without changing any fundamental
> > design or architecture. All changes are self-contained, straightforward,
> > and focues on improving correctness and maintainability.
> > 
> > The patches include:
> > 
> >   * Removal of obsolete FIXMEs that no longer reflect the current code
> >     or hardware behavior.
> >   * Correctness fixes in several protocol drivers (UART, RAW, USB,
> >     Loopback, Firmware core, Audio).
> >   * Small improvements to error handling and shutdown paths.
> >   * Cleanup of commented-out or dead code.
> >   * Removal of the now-completed GPIO and PWM TODO items.
> >   * Removal of the empty Greybus TODO file.
> > 
> > All patches were compile-tested with COMPILE_TEST=y and all Greybus
> > options enabled. Runtime smoke testing was performed where possible.
> > 
> > This series does not attempt to graduate Greybus out of staging; these
> > changes are preparatory cleanups only.
> > 
> > Thanks for your time and review.
> > 
> > Ayaan Mirza Baig (13):
> >   staging: greybus: Remove completed GPIO conversion TODO item
> >   staging: greybus: pwm: move activation into pwm apply and remove
> >     request()
> >   staging: greybus: remove empty TODO file
> >   staging: greybus: audio: remove obsolete INPUT_PROP_NO_DUMMY_RELEASE
> >     FIXME
> >   staging: greybus: audio: remove obsolete FIXME and document topology
> >     ownership
> >   staging: greybus: bootrom: remove obsolete FIXME about SVC parallel
> >     event handling
> >   staging: greybus: bootrom: remove obsolete FIXME around firmware
> >     filename logging
> >   staging: greybus: fw-core: remove obsolete S2 Loader runtime PM FIXME
> >   staging: greybus: loopback: remove incorrect FIXME about async wait
> >   staging: greybus: raw: handle disconnect while chardev is open
> >   staging: greybus: uart: clear unsupported termios bits
> >   staging: greybus: usb: validate hub control response length
> >   staging: greybus: usb: remove obsolete FIXME about bridged-PHY support
> 
> I only skimmed some of these and there are so many bugs and
> misunderstandings here that I can only imagine what's lurking in the
> remaining ones.
> 
> The basic misunderstanding seems to be that FIXMEs can and should be
> removed without addressing the underlying issues.
> 
> Johan

Hi Johan,

Thank you for taking the time to review the series, and thank you for being
direct about the issues. I want to apologize for the misunderstandings and
for removing FIXMEs that should not have been touched. That was my mistake,
and I should have taken more care before modifying areas of the subsystem
I don't fully understand yet.

I also want to be transparent: I'm an undergraduate student who is just
starting to learn kernel development. I'm very interested in Linux and
want to contribute seriously, but I clearly approached this series with
more confidence than understanding, and I am sorry for the noise that caused.

I'll resend only a very small, focused series once I have properly analysed
the code. Before I send a v2, I want to make sure I am going in the right direction.

If you have any guidance on how I can improve - in terms of approach,
review process, or how to evaluate FIXMEs and TODOs correctly - I would
really appreciate it. I'm trying to learn the right way to contribute and I
don't want to repeat the same mistakes.

I also want to double-check whether the PWM apply() changes (one of the
TODO items) were done correctly, also if there are any issues in
[PATCH 10/13], apart from what Abdun suggested.
I'm willing to redo the work properly.

Again, apologies for the errors. I appreciate your time and feedback.

Thanks,
Ayaan

Re: [PATCH 01/13] staging: greybus: Remove completed GPIO conversion TODO item

[Greg KH]

On Mon, Nov 17, 2025 at 11:48:06PM +0530, Ayaan Mirza Baig wrote:
> Signed-off-by: Ayaan Mirza Baig <ayaanmirzabaig85@gmail.com>
> ---
>  drivers/staging/greybus/TODO | 3 ---
>  1 file changed, 3 deletions(-)

For obvious reasons I can't take a patch without any changelog text
(hint, you don't want me to do that either...)

thanks,

greg k-h