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[96.239.109.94]) by smtp.gmail.com with ESMTPSA id af79cd13be357-93bedac2955sm47668285a.24.2026.09.18.15.07.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Sep 2026 15:07:32 -0700 (PDT) From: David Wood To: mchehab@kernel.org Cc: linux-media@vger.kernel.org Subject: Re: [PATCH] media: em28xx: fix silent audio capture on EM2860/TVP5150 reference design Date: Fri, 18 Sep 2026 18:07:25 -0400 Message-ID: <20260918220725.2040896-1-d01.devel@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260913231013.30b18fcc@foz.lan> References: <20260913231013.30b18fcc@foz.lan> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Sun, 13 Sep 2026 23:10:13 +0200, Mauro Carvalho Chehab wrote: > Instead of touching the reference design, and except if you have the > real em2861 reference card (unlikely unless you're a manufacturer or > if some manufacturer donated one to you), you need to create a > board-specific entry with the brand name used on it, and use > card=. Agreed. It is a retail StarTech.com SVID2USB23. v2 adds a board entry for it and leaves the reference design entry alone. Since the USB ID is the generic eb1a:5051, v2 identifies the board by EEPROM hash (0x11b79572), the way em28xx_eeprom_hash[] already does for other boards with shared IDs, with a lookup in em28xx_card_setup() for devices that arrive as the reference design. Boards that do not match a hash keep the reference design entry exactly as before, with no extra log output. card=114 also works. > It may also mean that the AC97 chip - either emp202 or a different > model - is wired on a non-standard way. Those chips have multiple > inputs that are wired on different ways depending on the board. It is an EMP202 (vendor ID reads back as such, features 0x6a90) and Line In is wired as on the reference design: with the record source set to Line In the capture is clean line level. The only thing missing is that nothing ever programs the ADC record source, because audio on this board leaves over a USB Audio Class endpoint fed by the EMP202 ADC rather than the em28xx vendor path, and .amux only reaches the mixer volume registers. > Please use your name instead of "d01". Done. > Most boards don't require adjusting aout. On most cases, just amux is > needed. The above setup also sounds weird: why does it need 3 audio > lines there? Two are needed. em28xx_audio_analog_set() only writes AC97_REC_SEL when EM28XX_AOUT_PCM_IN is set, and EM28XX_AOUT_PCM_LINE is what selects Line In as the record source, so v2 uses exactly those two, matching the other entries that set PCM_IN. EM28XX_AOUT_MASTER was only carried over from the old fallback so the master volume register would keep tracking the V4L2 volume control; it has no effect on capture on this board, so it is gone in v2. Thanks for the review, David