queue-6.6/hid-logitech-hidpp-do-not-assume-fap-in-hidpp_send_m.patch

From ce84ebf68593dad865b359752712f4d4ed275e52 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Thu, 2 Oct 2025 19:30:58 +0000
Subject: HID: logitech-hidpp: Do not assume FAP in hidpp_send_message_sync()

From: Mavroudis Chatzilazaridis <mavchatz@protonmail.com>

[ Upstream commit aba7963544d47d82cdf36602a6678a093af0299d ]

Currently, hidpp_send_message_sync() retries sending the message when the
device returns a busy error code, specifically HIDPP20_ERROR_BUSY, which
has a different meaning under RAP. This ends up being a problem because
this function is used for both FAP and RAP messages.

This issue is not noticeable on older receivers with unreachable devices
since they return HIDPP_ERROR_RESOURCE_ERROR (0x09), which is not equal to
HIDPP20_ERROR_BUSY (0x08).

However, newer receivers return HIDPP_ERROR_UNKNOWN_DEVICE (0x08) which
happens to equal to HIDPP20_ERROR_BUSY, causing unnecessary retries when
the device is not actually busy.

This is resolved by checking if the error response is FAP or RAP and
picking the respective ERROR_BUSY code.

Fixes: 60165ab774cb ("HID: logitech-hidpp: rework one more time the retries attempts")
Signed-off-by: Mavroudis Chatzilazaridis <mavchatz@protonmail.com>
Tested-by: Stuart Hayhurst <stuart.a.hayhurst@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hid/hid-logitech-hidpp.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index 3a2c1e48aba20..5a2fe703cf57b 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -351,10 +351,15 @@ static int hidpp_send_message_sync(struct hidpp_device *hidpp,
 
 	do {
 		ret = __do_hidpp_send_message_sync(hidpp, message, response);
-		if (ret != HIDPP20_ERROR_BUSY)
+		if (response->report_id == REPORT_ID_HIDPP_SHORT &&
+		    ret != HIDPP_ERROR_BUSY)
+			break;
+		if ((response->report_id == REPORT_ID_HIDPP_LONG ||
+		     response->report_id == REPORT_ID_HIDPP_VERY_LONG) &&
+		    ret != HIDPP20_ERROR_BUSY)
 			break;
 
-		dbg_hid("%s:got busy hidpp 2.0 error %02X, retrying\n", __func__, ret);
+		dbg_hid("%s:got busy hidpp error %02X, retrying\n", __func__, ret);
 	} while (--max_retries);
 
 	mutex_unlock(&hidpp->send_mutex);
-- 
2.51.0