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Groups > linux.kernel > #1301816

[PATCH 3.12 45/91] ALSA: usb-audio: work around CH345 input SysEx corruption

From Jiri Slaby <jslaby@suse.cz>
Newsgroups linux.kernel
Subject [PATCH 3.12 45/91] ALSA: usb-audio: work around CH345 input SysEx corruption
Date 2016-01-05 19:10 +0100
Message-ID <qNEdu-6sw-59@gated-at.bofh.it> (permalink)
References <qNDU6-65D-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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From: Clemens Ladisch <clemens@ladisch.de>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit a91e627e3f0ed820b11d86cdc04df38f65f33a70 upstream.

One of the many faults of the QinHeng CH345 USB MIDI interface chip is
that it does not handle received SysEx messages correctly -- every second
event packet has a wrong code index number, which is the one from the last
seen message, instead of 4.  For example, the two messages "FE F0 01 02 03
04 05 06 07 08 09 0A 0B 0C 0D 0E F7" result in the following event
packets:

correct:       CH345:
0F FE 00 00    0F FE 00 00
04 F0 01 02    04 F0 01 02
04 03 04 05    0F 03 04 05
04 06 07 08    04 06 07 08
04 09 0A 0B    0F 09 0A 0B
04 0C 0D 0E    04 0C 0D 0E
05 F7 00 00    05 F7 00 00

A class-compliant driver must interpret an event packet with CIN 15 as
having a single data byte, so the other two bytes would be ignored.  The
message received by the host would then be missing two bytes out of six;
in this example, "F0 01 02 03 06 07 08 09 0C 0D 0E F7".

These corrupted SysEx event packages contain only data bytes, while the
CH345 uses event packets with a correct CIN value only for messages with
a status byte, so it is possible to distinguish between these two cases by
checking for the presence of this status byte.

(Other bugs in the CH345's input handling, such as the corruption resulting
from running status, cannot be worked around.)

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 sound/usb/midi.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/sound/usb/midi.c b/sound/usb/midi.c
index 966051f530bd..9123fc518f07 100644
--- a/sound/usb/midi.c
+++ b/sound/usb/midi.c
@@ -174,6 +174,8 @@ struct snd_usb_midi_in_endpoint {
 		u8 running_status_length;
 	} ports[0x10];
 	u8 seen_f5;
+	bool in_sysex;
+	u8 last_cin;
 	u8 error_resubmit;
 	int current_port;
 };
@@ -465,6 +467,39 @@ static void snd_usbmidi_maudio_broken_running_status_input(
 }
 
 /*
+ * QinHeng CH345 is buggy: every second packet inside a SysEx has not CIN 4
+ * but the previously seen CIN, but still with three data bytes.
+ */
+static void ch345_broken_sysex_input(struct snd_usb_midi_in_endpoint *ep,
+				     uint8_t *buffer, int buffer_length)
+{
+	unsigned int i, cin, length;
+
+	for (i = 0; i + 3 < buffer_length; i += 4) {
+		if (buffer[i] == 0 && i > 0)
+			break;
+		cin = buffer[i] & 0x0f;
+		if (ep->in_sysex &&
+		    cin == ep->last_cin &&
+		    (buffer[i + 1 + (cin == 0x6)] & 0x80) == 0)
+			cin = 0x4;
+#if 0
+		if (buffer[i + 1] == 0x90) {
+			/*
+			 * Either a corrupted running status or a real note-on
+			 * message; impossible to detect reliably.
+			 */
+		}
+#endif
+		length = snd_usbmidi_cin_length[cin];
+		snd_usbmidi_input_data(ep, 0, &buffer[i + 1], length);
+		ep->in_sysex = cin == 0x4;
+		if (!ep->in_sysex)
+			ep->last_cin = cin;
+	}
+}
+
+/*
  * CME protocol: like the standard protocol, but SysEx commands are sent as a
  * single USB packet preceded by a 0x0F byte.
  */
@@ -650,6 +685,12 @@ static struct usb_protocol_ops snd_usbmidi_cme_ops = {
 	.output_packet = snd_usbmidi_output_standard_packet,
 };
 
+static struct usb_protocol_ops snd_usbmidi_ch345_broken_sysex_ops = {
+	.input = ch345_broken_sysex_input,
+	.output = snd_usbmidi_standard_output,
+	.output_packet = snd_usbmidi_output_standard_packet,
+};
+
 /*
  * AKAI MPD16 protocol:
  *
@@ -2292,6 +2333,7 @@ int snd_usbmidi_create(struct snd_card *card,
 		err = snd_usbmidi_detect_per_port_endpoints(umidi, endpoints);
 		break;
 	case QUIRK_MIDI_CH345:
+		umidi->usb_protocol_ops = &snd_usbmidi_ch345_broken_sysex_ops;
 		err = snd_usbmidi_detect_per_port_endpoints(umidi, endpoints);
 		break;
 	default:
-- 
2.6.4

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    [PATCH 3.12 62/91] USB: cp210x: Remove CP2110 ID from compatibility list Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:00 +0100
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    [PATCH 3.12 57/91] nfs4: start callback_ident at idr 1 Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:00 +0100
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    [PATCH 3.12 37/91] arm64: Fix compat register mappings Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
    [PATCH 3.12 30/91] net: mvneta: Fix CPU_MAP registers initialisation Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
    [PATCH 3.12 26/91] x86/setup: Fix low identity map for >= 2GB kernel range Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
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    [PATCH 3.12 55/91] ext4, jbd2: ensure entering into panic after recording an error in superblock Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
    [PATCH 3.12 66/91] gre6: allow to update all parameters via rtnl Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
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    [PATCH 3.12 54/91] ext4: fix potential use after free in __ext4_journal_stop Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
    [PATCH 3.12 24/91] ARM: common: edma: Fix channel parameter for irq callbacks Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
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    [PATCH 3.12 39/91] usb: musb: core: fix order of arguments to ulpi write callback Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
    [PATCH 3.12 45/91] ALSA: usb-audio: work around CH345 input SysEx corruption Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
    [PATCH 3.12 40/91] USB: ti_usb_3410_5052: Add Honeywell HGI80 ID Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
    [PATCH 3.12 31/91] mwifiex: fix mwifiex_rdeeprom_read() Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
    [PATCH 3.12 52/91] Btrfs: fix race leading to incorrect item deletion when dropping extents Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
    [PATCH 3.12 33/91] Bluetooth: hidp: fix device disconnect on idle timeout Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
    [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover whole kernel range Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
      Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover  whole kernel range Paolo Bonzini <pbonzini@redhat.com> - 2016-01-06 11:50 +0100
        Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover  whole kernel range Matt Fleming <matt@codeblueprint.co.uk> - 2016-01-06 12:10 +0100
          Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover  whole kernel range Luis Henriques <luis.henriques@canonical.com> - 2016-01-06 12:30 +0100
            Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover  whole kernel range Matt Fleming <matt@codeblueprint.co.uk> - 2016-01-06 14:40 +0100
              Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover  whole kernel range Luis Henriques <luis.henriques@canonical.com> - 2016-01-06 15:30 +0100
                Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover  whole kernel range Matt Fleming <matt@codeblueprint.co.uk> - 2016-01-08 13:00 +0100
                Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover  whole kernel range Luis Henriques <luis.henriques@canonical.com> - 2016-01-08 14:40 +0100
                Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover  whole kernel range Jiri Slaby <jslaby@suse.cz> - 2016-01-09 08:10 +0100
                Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover  whole kernel range Kamal Mostafa <kamal@canonical.com> - 2016-01-14 22:00 +0100
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    [PATCH 3.12 44/91] ALSA: usb-audio: prevent CH345 multiport output SysEx corruption Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
    [PATCH 3.12 35/91] Bluetooth: ath3k: Add support of AR3012 0cf3:817b device Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
    [PATCH 3.12 28/91] x86/cpu: Fix SMAP check in PVOPS environments Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
    [PATCH 3.12 49/91] netfilter: ip6t_SYNPROXY: fix NULL pointer dereference Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
    [PATCH 3.12 42/91] USB: option: add XS Stick W100-2 from 4G Systems Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
    [PATCH 3.12 10/91] net: qmi_wwan: add XS Stick W100-2 from 4G Systems Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
    [PATCH 3.12 11/91] tcp: md5: fix lockdep annotation Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
    [PATCH 3.12 19/91] net/neighbour: fix crash at dumping device-agnostic proxy entries Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
    [PATCH 3.12 23/91] ARM: 8427/1: dma-mapping: add support for offset parameter in dma_mmap() Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
    [PATCH 3.12 07/91] packet: infer protocol from ethernet header if unset Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
    [PATCH 3.12 21/91] Bluetooth: ath3k: Add support of 04ca:300d AR3012 device Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
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    [PATCH 3.12 22/91] ARM: 8426/1: dma-mapping: add missing range check in dma_mmap() Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
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    [PATCH 3.12 20/91] ipv6: sctp: implement sctp_v6_destroy_sock() Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
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  Re: [PATCH 3.12 00/91] 3.12.52-stable review Guenter Roeck <linux@roeck-us.net> - 2016-01-05 21:50 +0100
    Re: [PATCH 3.12 00/91] 3.12.52-stable review Jiri Slaby <jslaby@suse.cz> - 2016-01-09 09:50 +0100
  Re: [PATCH 3.12 00/91] 3.12.52-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2016-01-05 22:20 +0100
  Re: [PATCH 3.12 00/91] 3.12.52-stable review Nikolay Borisov <kernel@kyup.com> - 2016-01-06 08:40 +0100
    Re: [PATCH 3.12 00/91] 3.12.52-stable review Greg KH <gregkh@linuxfoundation.org> - 2016-01-06 09:20 +0100

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