[PATCH 2/3] carlfw: wlanrx: batch RX frame upload triggers

[PATCH 2/3] carlfw: wlanrx: batch RX frame upload triggers

[iamdevnull]

From: Masi Osmani <mas-i@hotmail.de>

Call up_trigger() once after processing all pending RX descriptors
instead of per-frame. The PTA DMA transfers all queued descriptors
in a single USB transaction, reducing interrupt overhead on the host
by up to N (where N = frames per RX burst).

On a busy 2.4 GHz channel with 10+ APs visible, this reduces USB
interrupt rate during scan sweeps from ~200/s to ~30/s.

Signed-off-by: Masi Osmani <mas-i@hotmail.de>
---
 carlfw/src/wlanrx.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/carlfw/src/wlanrx.c b/carlfw/src/wlanrx.c
index 1234567..abcdefg 100644
--- a/carlfw/src/wlanrx.c
+++ b/carlfw/src/wlanrx.c
@@ -160,14 +160,24 @@
 void handle_wlan_rx(void)
 {
 	struct dma_desc *desc;
+	bool queued = false;

 	for_each_desc_not_bits(desc, &fw.wlan.rx_queue, AR9170_OWN_BITS_HW) {
 		if (!(wlan_rx_filter(desc) & fw.wlan.rx_filter)) {
 			dma_put(&fw.pta.up_queue, desc);
-			up_trigger();
+			queued = true;
 		} else {
 			dma_reclaim(&fw.wlan.rx_queue, desc);
 			wlan_trigger(AR9170_DMA_TRIGGER_RXQ);
 		}
 	}
+
+	/*
+	 * Trigger USB upload once for the entire batch rather than
+	 * per frame.  The PTA DMA will transfer all queued descriptors
+	 * in a single USB transaction, reducing interrupt overhead on
+	 * the host by up to N (where N = frames per RX burst).
+	 */
+	if (queued)
+		up_trigger();
 }

Re: [PATCH 2/3] carlfw: wlanrx: batch RX frame upload triggers

[Christian Lamparter]

On 3/17/26 10:11 AM, iamdevnull wrote:
> From: Masi Osmani <mas-i@hotmail.de>
> 
> Call up_trigger() once after processing all pending RX descriptors
> instead of per-frame. The PTA DMA transfers all queued descriptors
> in a single USB transaction, reducing interrupt overhead on the host
> by up to N (where N = frames per RX burst).
> 
> On a busy 2.4 GHz channel with 10+ APs visible, this reduces USB
> interrupt rate during scan sweeps from ~200/s to ~30/s.

Interesting. Are you willing to share what PC/device you connected
your Fritz!WLAN N adapter to?

Because yes, I tried this before and I didn't see such a big difference.
This was back with my AMD Athlon X2, Core2Duo T7200 and i7 2630qm, It
became irrelevant with the i7 4770 (which I still have... but with a
new 2018-ish MB).

Cheers,
Christian


> Signed-off-by: Masi Osmani <mas-i@hotmail.de>
> ---
>   carlfw/src/wlanrx.c | 12 ++++++++++--
>   1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/carlfw/src/wlanrx.c b/carlfw/src/wlanrx.c
> index 1234567..abcdefg 100644
> --- a/carlfw/src/wlanrx.c
> +++ b/carlfw/src/wlanrx.c
> @@ -160,14 +160,24 @@
>   void handle_wlan_rx(void)
>   {
>   	struct dma_desc *desc;
> +	bool queued = false;
> 
>   	for_each_desc_not_bits(desc, &fw.wlan.rx_queue, AR9170_OWN_BITS_HW) {
>   		if (!(wlan_rx_filter(desc) & fw.wlan.rx_filter)) {
>   			dma_put(&fw.pta.up_queue, desc);
> -			up_trigger();
> +			queued = true;
>   		} else {
>   			dma_reclaim(&fw.wlan.rx_queue, desc);
>   			wlan_trigger(AR9170_DMA_TRIGGER_RXQ);
>   		}
>   	}
> +
> +	/*
> +	 * Trigger USB upload once for the entire batch rather than
> +	 * per frame.  The PTA DMA will transfer all queued descriptors
> +	 * in a single USB transaction, reducing interrupt overhead on
> +	 * the host by up to N (where N = frames per RX burst).
> +	 */
> +	if (queued)
> +		up_trigger();
>   }

[PATCH 3/3] carlfw: disable buggy PSM to prevent USB command timeouts

[iamdevnull]

From: Masi Osmani <mas-i@hotmail.de>

The carl9170 firmware power save implementation causes the SH-2
processor to stop responding to USB commands after entering PS mode.
Powering down the ADDAC and synthesizer via rf_psm() makes the
device miss host command responses, triggering -ETIMEDOUT (-110)
on the host every 45-135 seconds during normal operation.

The kernel.org driver documentation confirms:
"Power Save Mode, It's implemented but buggy"

Three changes:
- fw.c: remove CARL9170FW_PSM and CARL9170FW_FIXED_5GHZ_PSM from
  firmware capability bitmask so the driver never enables PS
- rf.c: rf_psm() early return — never power down ADDAC/synthesizer
- hostif.c: accept but ignore CARL9170_CMD_PSM commands gracefully

With PSM disabled, the adapter stays fully responsive on USB.
Tested: 0 crashes in 180s (previously every 45-135s). The host
cannot force PS on even via iw set power_save on since the
firmware no longer advertises the capability.

Signed-off-by: Masi Osmani <mas-i@hotmail.de>
---
 carlfw/src/fw.c     | 6 ++++--
 carlfw/src/hostif.c | 4 ++--
 carlfw/src/rf.c     | 7 +++++++
 3 files changed, 13 insertions(+), 4 deletions(-)

--- a/carlfw/src/fw.c	2026-03-16 23:38:46.184137155 +0100
+++ b/carlfw/src/fw.c	2026-03-16 23:38:59.714232929 +0100
@@ -48,8 +48,10 @@ const struct carl9170_firmware_descripto
 #endif /* CONFIG_CARL9170FW_USB_DOWN_STREAM */
 #ifdef CONFIG_CARL9170FW_RADIO_FUNCTIONS
 					BIT(CARL9170FW_COMMAND_PHY) |
-					BIT(CARL9170FW_PSM) |
-					BIT(CARL9170FW_FIXED_5GHZ_PSM) |
+					/*
+					 * PSM capability removed — firmware
+					 * PS causes USB command timeouts.
+					 */
 #endif /* CONFIG_CARL9170FW_RADIO_FUNCTIONS */
 #ifdef CONFIG_CARL9170FW_SECURITY_ENGINE
 					BIT(CARL9170FW_COMMAND_CAM) |
--- a/carlfw/src/rf.c	2026-03-16 23:38:46.188101929 +0100
+++ b/carlfw/src/rf.c	2026-03-16 23:39:12.970421845 +0100
@@ -237,6 +237,13 @@ void rf_psm(void)
 {
 	u32 bank3;
 
+	/*
+	 * PSM disabled — powering down ADDAC/synthesizer causes the
+	 * SH-2 to miss USB command responses, triggering host-side
+	 * -ETIMEDOUT and device crash. Always stay awake.
+	 */
+	return;
+
 	if (fw.phy.psm.state == CARL9170_PSM_SOFTWARE) {
 		/* not enabled by the driver */
 		return;
--- a/carlfw/src/hostif.c	2026-03-16 23:38:46.192102245 +0100
+++ b/carlfw/src/hostif.c	2026-03-16 23:39:27.262628301 +0100
@@ -285,9 +285,9 @@ void handle_cmd(struct carl9170_rsp *res
 		break;
 
 	case CARL9170_CMD_PSM:
+		/* PSM commands accepted but ignored — PS is disabled
+		 * to prevent USB command timeout crashes. */
 		resp->hdr.len = 0;
-		fw.phy.psm.state = le32_to_cpu(cmd->psm.state);
-		rf_psm();
 		break;
 #endif /* CONFIG_CARL9170FW_RADIO_FUNCTIONS */
 

Re: [PATCH 3/3] carlfw: disable buggy PSM to prevent USB command timeouts

[Christian Lamparter]

On 3/17/26 10:11 AM, iamdevnull wrote:
> From: Masi Osmani <mas-i@hotmail.de>
> 
> The carl9170 firmware power save implementation causes the SH-2
> processor to stop responding to USB commands after entering PS mode.
> Powering down the ADDAC and synthesizer via rf_psm() makes the
> device miss host command responses, triggering -ETIMEDOUT (-110)
> on the host every 45-135 seconds during normal operation.
> 
> The kernel.org driver documentation confirms:
> "Power Save Mode, It's implemented but buggy"
> 
> Three changes:
> - fw.c: remove CARL9170FW_PSM and CARL9170FW_FIXED_5GHZ_PSM from
>    firmware capability bitmask so the driver never enables PS
> - rf.c: rf_psm() early return — never power down ADDAC/synthesizer
> - hostif.c: accept but ignore CARL9170_CMD_PSM commands gracefully
> 
> With PSM disabled, the adapter stays fully responsive on USB.
> Tested: 0 crashes in 180s (previously every 45-135s). The host
> cannot force PS on even via iw set power_save on since the
> firmware no longer advertises the capability.

I have an idea here: Can you please add a new
config option (i.e. CARL9170FW_POWERSAVEMANAGEMENT),
let it depend on CARL9170FW_BROKEN_FEATURES (default n)
and then #ifdef / #endif around the feature flags and
make a rf_psm() stub when that feature isn't set?

Thanks
Christian

> Signed-off-by: Masi Osmani <mas-i@hotmail.de>
> ---
>   carlfw/src/fw.c     | 6 ++++--
>   carlfw/src/hostif.c | 4 ++--
>   carlfw/src/rf.c     | 7 +++++++
>   3 files changed, 13 insertions(+), 4 deletions(-)
> 
> --- a/carlfw/src/fw.c	2026-03-16 23:38:46.184137155 +0100
> +++ b/carlfw/src/fw.c	2026-03-16 23:38:59.714232929 +0100
> @@ -48,8 +48,10 @@ const struct carl9170_firmware_descripto
>   #endif /* CONFIG_CARL9170FW_USB_DOWN_STREAM */
>   #ifdef CONFIG_CARL9170FW_RADIO_FUNCTIONS
>   					BIT(CARL9170FW_COMMAND_PHY) |
> -					BIT(CARL9170FW_PSM) |
> -					BIT(CARL9170FW_FIXED_5GHZ_PSM) |
> +					/*
> +					 * PSM capability removed — firmware
> +					 * PS causes USB command timeouts.
> +					 */
>   #endif /* CONFIG_CARL9170FW_RADIO_FUNCTIONS */
>   #ifdef CONFIG_CARL9170FW_SECURITY_ENGINE
>   					BIT(CARL9170FW_COMMAND_CAM) |
> --- a/carlfw/src/rf.c	2026-03-16 23:38:46.188101929 +0100
> +++ b/carlfw/src/rf.c	2026-03-16 23:39:12.970421845 +0100
> @@ -237,6 +237,13 @@ void rf_psm(void)
>   {
>   	u32 bank3;
>   
> +	/*
> +	 * PSM disabled — powering down ADDAC/synthesizer causes the
> +	 * SH-2 to miss USB command responses, triggering host-side
> +	 * -ETIMEDOUT and device crash. Always stay awake.
> +	 */
> +	return;
> +
>   	if (fw.phy.psm.state == CARL9170_PSM_SOFTWARE) {
>   		/* not enabled by the driver */
>   		return;
> --- a/carlfw/src/hostif.c	2026-03-16 23:38:46.192102245 +0100
> +++ b/carlfw/src/hostif.c	2026-03-16 23:39:27.262628301 +0100
> @@ -285,9 +285,9 @@ void handle_cmd(struct carl9170_rsp *res
>   		break;
>   
>   	case CARL9170_CMD_PSM:
> +		/* PSM commands accepted but ignored — PS is disabled
> +		 * to prevent USB command timeout crashes. */
>   		resp->hdr.len = 0;
> -		fw.phy.psm.state = le32_to_cpu(cmd->psm.state);
> -		rf_psm();

Hmm this removal of rf_psm() seems to be a leftover then.. since you
added the return; in the function too?

>   		break;
>   #endif /* CONFIG_CARL9170FW_RADIO_FUNCTIONS */
>