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Mon, 7 Sep 2026 07:56:54 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id dE7oC0ZunmqwIQAAD6G6ig (envelope-from ); Mon, 07 Sep 2026 07:56:54 +0000 Date: Mon, 07 Sep 2026 09:56:53 +0200 Message-ID: <87pkyp335m.wl-tiwai@suse.de> From: Takashi Iwai To: Geraldo Nascimento Cc: Hanh Kieu , perex@perex.cz, tiwai@suse.com, linux-sound@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ALSA: usb-audio: add Pioneer DJ DDJ-SZ support In-Reply-To: References: <20260904182023.4486-1-hhkieu@gmail.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) Emacs/30.2 Mule/6.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Spam-Level: X-Spam-Score: -3.30 X-Spam-Flag: NO X-Spamd-Result: default: False [-3.30 / 50.00]; BAYES_HAM(-3.00)[99.99%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; RCVD_TLS_ALL(0.00)[]; ARC_NA(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; MIME_TRACE(0.00)[0:+]; RCVD_VIA_SMTP_AUTH(0.00)[]; TO_DN_SOME(0.00)[]; FREEMAIL_TO(0.00)[gmail.com]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FREEMAIL_CC(0.00)[gmail.com,perex.cz,suse.com,vger.kernel.org]; RCPT_COUNT_FIVE(0.00)[6]; FROM_HAS_DN(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:mid,imap1.dmz-prg2.suse.org:helo] On Sat, 05 Sep 2026 08:19:37 +0200, Geraldo Nascimento wrote: > > On Sat, Sep 5, 2026 at 2:35 AM Hanh Kieu wrote: > > > > Hi Geraldo, > > > > I looked further into the is_pioneer_implicit_fb() check you pointed out. > > > > It seems the DATA case is intentional. In the original Pioneer DJM-900NXS2 work, Fabian Lesniak described the observed behavior as: > > > > “the playback streams also tries to start the capture endpoint as sync source.” > > > > https://gist.github.com/flesniak/074ab23bbc833663b782f44174eae6a4 > > > > Takashi Iwai later formalized this in the Pioneer implicit-feedback handling, explicitly accepting either USB_ENDPOINT_USAGE_DATA or USB_ENDPOINT_USAGE_IMPLICIT_FB for the secondary IN endpoint before passing it to add_implicit_fb_sync_ep(): > > > > https://github.com/torvalds/linux/commit/167c9dc84ec384c0940359e067301883ad2b42a8 > > > > Every other Pioneer device has that USB_ENDPOINT_USAGE_IMPLICIT_FB > on the IN endpoint. Yours would be the first without it in the IN > endpoint. Unless > your hardware doesn't rely on implicit feedback for syncing then there's a good > chance that implicit.c short-circuiting and still picking up implicit > feedback for you > isn't correct, but what you need to do is cool down now and wait for proper > maintainer response which takes time. Accepting both DATA and IMPLICIT_FB usages is intentional, yes. But I don't follow what's the problem there -- in this case, the bmAttributes of the secondary EP shows it's DATA, no? Then this check must pass. The condition is: if (!usb_endpoint_is_isoc_in(epd) || (epd->bmAttributes & USB_ENDPOINT_SYNCTYPE) != USB_ENDPOINT_SYNC_ASYNC || ((epd->bmAttributes & USB_ENDPOINT_USAGE_MASK) != USB_ENDPOINT_USAGE_DATA && (epd->bmAttributes & USB_ENDPOINT_USAGE_MASK) != USB_ENDPOINT_USAGE_IMPLICIT_FB)) return false; return false; ... and maybe it's better to be rewritten like: sync = (epd->bmAttributes & USB_ENDPOINT_SYNCTYPE); usage = (epd->bmAttributes & USB_ENDPOINT_USAGE_MASK); if (usb_endpoint_is_isoc_in(epd) && sync == USB_ENDPOINT_SYNC_ASYNC && (usage == USB_ENDPOINT_USAGE_DATA || usage == USB_ENDPOINT_USAGE_IMPLICIT_FB)) return true; return false; So it should return true. Please double-check which test actually fails. thanks, Takashi