linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: <chihhao.chen@mediatek.com>
To: <linux-mediatek@lists.infradead.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>, <alsa-devel@alsa-project.org>,
	<damien@zamaudio.com>, <chihhao.chen@mediatek.com>,
	<perex@perex.cz>, <tiwai@suse.com>, <matthias.bgg@gmail.com>
Cc: <wsd_upstream@mediatek.com>
Subject: [PATCH] ALSA: usb-audio: fix incorrect clock source setting
Date: Sat, 24 Jul 2021 12:23:41 +0800	[thread overview]
Message-ID: <1627100621-19225-1-git-send-email-chihhao.chen@mediatek.com> (raw)

From: "chihhao.chen" <chihhao.chen@mediatek.com>

The following scenario describes an echo test for
Samsung USBC Headset (AKG) with VID/PID (0x04e8/0xa051).

We first start a capture stream(USB IN transfer) in 96Khz/24bit/1ch mode.
In clock find source function, we get value 0x2 for clock selector
and 0x1 for clock source.

Kernel-4.14 behavior
Since clock source is valid so clock selector was not set again.
We pass through this function and start a playback stream(USB OUT transfer)
in 48Khz/32bit/2ch mode. This time we get value 0x1 for clock selector
and 0x1 for clock source. Finally clock id with this setting is 0x9.

Kernel-5.10 behavior
Clock selector was always set one more time even it is valid.
When we start a playback stream, we will get 0x2 for clock selector
and 0x1 for clock source. In this case clock id becomes 0xA.
This is an incorrect clock source setting and results in severe noises.
We see wrong data rate in USB IN transfer.
(From 288 bytes/ms becomes 144 bytes/ms) It should keep in 288 bytes/ms.

This earphone works fine on older kernel version load because
this is a newly-added behavior.

Signed-off-by: chihhao.chen <chihhao.chen@mediatek.com>
---
 sound/usb/clock.c |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/sound/usb/clock.c b/sound/usb/clock.c
index 52de522..14456f6 100644
--- a/sound/usb/clock.c
+++ b/sound/usb/clock.c
@@ -324,6 +324,12 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip,
 					      sources[ret - 1],
 					      visited, validate);
 		if (ret > 0) {
+			/*
+			 * For Samsung USBC Headset (AKG), setting clock selector again
+			 * will result in incorrect default clock setting problems
+			 */
+			if (chip->usb_id == USB_ID(0x04e8, 0xa051))
+				return ret;
 			err = uac_clock_selector_set_val(chip, entity_id, cur);
 			if (err < 0)
 				return err;
-- 
1.7.9.5


             reply	other threads:[~2021-07-24  4:24 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-24  4:23 chihhao.chen [this message]
2021-07-24  8:04 ` Takashi Iwai
2021-07-24 15:04   ` Geraldo Nascimento
2021-07-24 15:20     ` Geraldo Nascimento
2021-07-24 18:42       ` Geraldo Nascimento
2021-07-25  7:44     ` Takashi Iwai
2021-07-26  2:16       ` Geraldo Nascimento
2021-07-26  8:42         ` chihhao chen
2021-07-26 20:57           ` Geraldo Nascimento
2021-07-27 10:27             ` chihhao.chen
2021-07-27 17:56               ` Geraldo Nascimento
2021-07-28  1:19                 ` Geraldo Nascimento
2021-08-05  7:54             ` chihhao.chen
2021-08-05 15:50               ` Geraldo Nascimento
     [not found]                 ` <CAEsQvcvJeAXoVE9FE9vsKNvXMaQYgHZBoPyKfZLT=UA-4BMe_Q@mail.gmail.com>
2021-08-05 22:03                   ` Geraldo Nascimento

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1627100621-19225-1-git-send-email-chihhao.chen@mediatek.com \
    --to=chihhao.chen@mediatek.com \
    --cc=alsa-devel@alsa-project.org \
    --cc=damien@zamaudio.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mediatek@lists.infradead.org \
    --cc=matthias.bgg@gmail.com \
    --cc=perex@perex.cz \
    --cc=tiwai@suse.com \
    --cc=wsd_upstream@mediatek.com \
    --subject='Re: [PATCH] ALSA: usb-audio: fix incorrect clock source setting' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
on how to clone and mirror all data and code used for this inbox