linux-kernel - [PATCH 5.4 217/434] ALSA: bebob: expand sleep just after breaking connections for protocol version 1

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Date:   Sun, 29 Dec 2019 18:24:30 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Takashi Sakamoto <o-takashi@...amocchi.jp>,
        Takashi Iwai <tiwai@...e.de>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 217/434] ALSA: bebob: expand sleep just after breaking connections for protocol version 1

From: Takashi Sakamoto <o-takashi@...amocchi.jp>

[ Upstream commit d3eabe939aee3ffd5b133766a932629a9746298c ]

As long as I investigated, some devices with BeBoB protocol version 1
can be freezed during several hundreds milliseconds after breaking
connections. When accessing during the freezed time, any transaction
is corrupted. In the worst case, the device is going to reboot.

I can see this issue in:
 * Roland FA-66
 * M-Audio FireWire Solo

This commit expands sleep just after breaking connections to avoid
the freezed time as much as possible. I note that the freeze/reboot
behaviour is similar to below models:
 * Focusrite Saffire Pro 10 I/O
 * Focusrite Saffire Pro 26 I/O

The above models certainly reboot after breaking connections.

Signed-off-by: Takashi Sakamoto <o-takashi@...amocchi.jp>
Link: https://lore.kernel.org/r/20191101131323.17300-2-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 sound/firewire/bebob/bebob_stream.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/sound/firewire/bebob/bebob_stream.c b/sound/firewire/bebob/bebob_stream.c
index 6c1497d9f52b..ce07ea0d4e71 100644
--- a/sound/firewire/bebob/bebob_stream.c
+++ b/sound/firewire/bebob/bebob_stream.c
@@ -415,15 +415,16 @@ static int make_both_connections(struct snd_bebob *bebob)
 	return 0;
 }
 
-static void
-break_both_connections(struct snd_bebob *bebob)
+static void break_both_connections(struct snd_bebob *bebob)
 {
 	cmp_connection_break(&bebob->in_conn);
 	cmp_connection_break(&bebob->out_conn);
 
-	/* These models seems to be in transition state for a longer time. */
-	if (bebob->maudio_special_quirk != NULL)
-		msleep(200);
+	// These models seem to be in transition state for a longer time. When
+	// accessing in the state, any transactions is corrupted. In the worst
+	// case, the device is going to reboot.
+	if (bebob->version < 2)
+		msleep(600);
 }
 
 static int
-- 
2.20.1