[PATCH 3/4] firewire: core: handle device quirk of TASCAM FW-1884/FW-1804/FW-1082

[Takashi S. <o-t...@sa...>]

TASCAM FW-1884/FW-1804/FW-1082 is too lazy to repspond to asynchronous
request at S400. The asynchronous transaction often results in timeout.
This is a problematic quirk.

This commit adds support for the quirk. When identifying the new quirk
flag, then the transaction speed is configured at S200.

Signed-off-by: Takashi Sakamoto <o-t...@sa...>
---
 drivers/firewire/core-device.c | 18 +++++++++++++++++-
 include/linux/firewire.h       |  3 +++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index 6a5740ed4934..1674de477852 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -571,6 +571,14 @@ static const struct entry_match motu_audio_express_matches[] = {
 	{ 8, 0x17104800 },
 };
 
+static const struct entry_match tascam_fw_series_matches[] = {
+	{ 1, 0x0300022e },
+	{ 3, 0x8d000006 },
+	{ 4, 0xd1000001 },
+	{ 6, 0x1200022e },
+	{ 8, 0xd4000004 },
+};
+
 static int detect_quirks_by_root_directory(const u32 *root_directory, unsigned int length)
 {
 	static const struct {
@@ -583,6 +591,11 @@ static int detect_quirks_by_root_directory(const u32 *root_directory, unsigned i
 			.matches = motu_audio_express_matches,
 			.match_count = ARRAY_SIZE(motu_audio_express_matches),
 		},
+		{
+			.quirk = FW_DEVICE_QUIRK_UNSTABLE_AT_S400,
+			.matches = tascam_fw_series_matches,
+			.match_count = ARRAY_SIZE(tascam_fw_series_matches),
+		},
 	};
 	int quirks = 0;
 	int i;
@@ -761,7 +774,10 @@ static int read_config_rom(struct fw_device *device, int generation)
 	// Just prevent from torn writing/reading.
 	WRITE_ONCE(device->quirks, quirks);
 
-	speed = device->node->max_speed;
+	if (unlikely(quirks & FW_DEVICE_QUIRK_UNSTABLE_AT_S400))
+		speed = SCODE_200;
+	else
+		speed = device->node->max_speed;
 
 	// Determine the speed of
 	//   - devices with link speed less than PHY speed,
diff --git a/include/linux/firewire.h b/include/linux/firewire.h
index f1d8734c0ec6..6143b7d28eac 100644
--- a/include/linux/firewire.h
+++ b/include/linux/firewire.h
@@ -179,6 +179,9 @@ enum fw_device_quirk {
 
 	// MOTU Audio Express transfers acknowledge packet with 0x10 for pending state.
 	FW_DEVICE_QUIRK_ACK_PACKET_WITH_INVALID_PENDING_CODE = BIT(2),
+
+	// TASCAM FW-1082/FW-1804/FW-1884 often freezes when receiving S400 packets.
+	FW_DEVICE_QUIRK_UNSTABLE_AT_S400 = BIT(3),
 };
 
 enum fw_device_state {
-- 
2.51.0