From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.221.44 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794256484; b=wS0jxdZNHhjzSOyxAR9nY9hF5GrPfMM0A9IBrr6J5Jh7pMFK96pMF0for36VnnpMUWjm eOEZlaUJiFW+sc+xaSjkT8XWKpQTZSTvlGGFivB5lKkOzZrb/uO4kiM8WLO422/plMc4C n9xk9i7GVfwtyLuf2GrhpqRFiEgGXN1h1ucVEglbqxqqXe+4H62i/7uUs0OXcwgXibIjK LD50gZ5n45CDREQHCTIKb0gmQCWl5GA6HX1GRWtRuu85LXDVBjb5UYPLVG+oMIDFZ114W mUChxzTuCxvdJTdiEN2AvurWDo8ZOXAT7960kPkF2okQ2iEKmjbiiq750v52NKoamFg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794256484; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=IBxWV0bMHBiaBYABre4CeRklD+VEvSYRbNLDT7mR5OE=; b=RN5asxxDa+C+NRD06mKOA3HnznTWgoorot/ZtXOs6PkcJkdApV8SsFmGHM6nD99zEcBt wNCuFiMU1WYvwi9+6/C6t4mP11tm0X/uACYIAZrHlQZ04GsGH375YVy/FglkNaktDfY8R IAfGTVRtCKpsPm+KDzDH1xvk2j02+ArKk74LP+qF5VYuN0kt7eCQWkcFnJB6L17lU9sfX E/EFz19AwQ0LTXOut7AVmQw+pPVUNPsvA89AKE64PrlW/In821VC5sryn1g4442XOjP8W vfcIKCmgDxx59eDxpq44fNd8f6Dc3yG7cML+uezCe+Xkbekg9kXnz/QovamxL7NLYnw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=c9TmK+9W; arc=none smtp.remote-ip=209.85.221.44 Received: from mail-wr1-f44.google.com (mail-wr1-f44.google.com [209.85.221.44]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 87878606A31C for ; Mon, 9 Nov 2026 20:34:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 87878606A31C Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=c9TmK+9W Received: by mail-wr1-f44.google.com with SMTP id ffacd0b85a97d-490f38e9688so1063132f8f.0 for ; Mon, 09 Nov 2026 12:34:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20260707; t=1794256483; x=1794861283; darn=vger.kernel.org; h=content-transfer-encoding:content-type:mime-version:references :in-reply-to:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=IBxWV0bMHBiaBYABre4CeRklD+VEvSYRbNLDT7mR5OE=; b=c9TmK+9WzrGyvd+dKsPN5CRanNi3KrAxYt7LKAN24BULUbEELTKz9a3REq0gnaF1eU 96dkvLHUhT+Dey24BA803kWLvqWppZfKGlgK/KTSDJWb8BEvoi7SQKLyu0+qFBBTQre6 c3ApfaIZXvk4P+K3nfi3o4lJT5hPfKjNev4vephwJOukoaCVqawno6zNEU4T8EiQ2QXW 9yEl7K8t58m72puXrbI19fiGd0WImOk5Oiyyr49pOh9OIc3MUl6WSRXs2+54rV0TOQsK Ia7OO0PJANNhk8znn9Z2t/YF+YVTLM0vpswHDvvA4LmBeyZ/HMzX3fo3LpnpsBPzg7u7 xlGA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1794256483; x=1794861283; h=content-transfer-encoding:content-type:mime-version:references :in-reply-to:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=IBxWV0bMHBiaBYABre4CeRklD+VEvSYRbNLDT7mR5OE=; b=eXEO8Bepuu0QnUgx4EwRbIMopwPJ4asbURGZNEIDbxQl8utID/dlSM9JUsN77WxrHt RtwHDK6zUhqzsZMTvU7XV7wr/cJGk72Af53Q4NjtTEtI4gN1dQuttnyCVa+yjIZQ1POb Xxk782FsmfEpTo71amGwI7vFQxRU4Tww8W2luRgNxJTSItfl9Hlk356iAqUlMPEUyx9t KSMlfnCBSyOYRSv0uEhZvr+tQn7t80UR89EO2yonNRxVYphKjgQSpeew2IA0q43GbBvn glgKD3AudyvKLztNGfMee+t527ltKfL5GTtHyn1Eb3Nmfnr7s/+SnHYX80xf1ehsfxWE mCmw== X-Forwarded-Encrypted: i=1; AL+hErHbN1efGtBtzGgq1I5cmJT25Zha9LCr1gc+EZSQomdxL6pyaQIPyIxmZl0QHY6CoVgMzcMRTd8=@vger.kernel.org X-Gm-Message-State: APuU4Z8WtBQWk/xRn5fI5pAzAsXP26xf2DSUJ5h7H7YwqUuPUx7Zvfs8 uCNu/oOPths6Nhq/zZajq7cIbXZurCynI8F5GKbGQn0BITAV1d2sbCV1 X-Gm-Gg: AYBFou1MlkjLBbe7Hd+8lzWSDHr2tdScCW/SWZSyHComLmb035nZKf2ZIRcp9ckJIBG SDvTT8qwwgy4CjYyqC39E2k4j80WPJkGUpWLuECobsUQI9pj39oa4sRC+N0sx0F8YhbblXcsFVx Umjt88/3p73OjurZcHFs+tBZHXnF8hiWbAttb+5/FunSDgbXLvKU/SqFo7hwdxCNxtEK1Z64MYY crJG3UBdTsa9HRLsLO/A6ja2ixsmQtlkuhKW/asB2XCM4d9U86d63KuuZHgzhyu+gyULpS+BuIu 3g8NsBSnCy2HbAZrX23PZQ6+uc6AsvOzLuMS+HsrMR/amo7fZduIj+ZV/BO+MvolhKuJwNdfHSz gqqI7AsZloTrkP6DLavV2DHSyNyeJ13tV9LdESw8ilGOOze6Eo+BsSeOdYgeSkVxYKdo4D34Nyw 8lx4qQblQVjlonKQsXvMtXy9haG1uAlRpAhgAHNTfDCHlsKtBCGoA3MsHzJqKH6fsoMc6Rj2niS n4bWqjpVsG0LFClKxNiFBKDpRkUJyYFdL0M1Z04ryW8sEpa06XNmSkqmHHAZUHSpMqVo1AaUxbB NNIPtHv0luo7+uZaOQcG3+LixhDPOd92hRe1WqCn1/nAaDZx9kD14jpV4qk= X-Received: by 2002:a05:6000:4b10:b0:48e:678d:396e with SMTP id ffacd0b85a97d-4982e362a4emr1059772f8f.9.1794256482703; Mon, 09 Nov 2026 12:34:42 -0800 (PST) Received: from foxbook (bfj76.neoplus.adsl.tpnet.pl. [83.28.47.76]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-498365cbfc6sm917789f8f.41.2026.11.09.12.34.41 (version=TLS1_2 cipher=AES128-SHA bits=128/128); Mon, 09 Nov 2026 12:34:42 -0800 (PST) Date: Mon, 9 Nov 2026 21:34:37 +0100 From: Michal Pecio To: Alan Stern Cc: Pengfei Lv , gregkh@linuxfoundation.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, xuhaiyang5@hisilicon.com, xuetao09@huawei.com, caiyadong@huawei.com, suzhuangluan@hisilicon.com Subject: Re: [PATCH v3] usb: core: hub: Re-guess ep0 maxpacket size after reset Message-ID: <20261109213437.5c693895.michal.pecio@gmail.com> In-Reply-To: <3daf18d4-4936-4ed7-8846-b67f1664be13@rowland.harvard.edu> References: <20261106031625.1824732-1-lvpengfei20@huawei.com> <20261109093935.2634235-1-lvpengfei20@huawei.com> <3daf18d4-4936-4ed7-8846-b67f1664be13@rowland.harvard.edu> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 9 Nov 2026 11:05:30 -0500, Alan Stern wrote: > > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c > > index 199d3f535a89..d86bbba1457c 100644 > > --- a/drivers/usb/core/hub.c > > +++ b/drivers/usb/core/hub.c > > @@ -4969,31 +4969,29 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1, > > } > > oldspeed = udev->speed; > > > > - if (initial) { > > - /* USB 2.0 section 5.5.3 talks about ep0 maxpacket ... > > - * it's fixed size except for full speed devices. > > + /* USB 2.0 section 5.5.3 talks about ep0 maxpacket ... > > + * it's fixed size except for full speed devices. > > + */ > > + switch (udev->speed) { > > + case USB_SPEED_SUPER_PLUS: > > + case USB_SPEED_SUPER: > > + udev->ep0.desc.wMaxPacketSize = cpu_to_le16(512); > > + break; > > + case USB_SPEED_HIGH: /* fixed at 64 */ > > + udev->ep0.desc.wMaxPacketSize = cpu_to_le16(64); > > + break; > > + case USB_SPEED_FULL: /* 8, 16, 32, or 64 */ > > + /* to determine the ep0 maxpacket size, try to read > > + * the device descriptor to get bMaxPacketSize0 and > > + * then correct our initial guess. > > */ > > - switch (udev->speed) { > > - case USB_SPEED_SUPER_PLUS: > > - case USB_SPEED_SUPER: > > - udev->ep0.desc.wMaxPacketSize = cpu_to_le16(512); > > - break; > > - case USB_SPEED_HIGH: /* fixed at 64 */ > > - udev->ep0.desc.wMaxPacketSize = cpu_to_le16(64); > > - break; > > - case USB_SPEED_FULL: /* 8, 16, 32, or 64 */ > > - /* to determine the ep0 maxpacket size, try to read > > - * the device descriptor to get bMaxPacketSize0 and > > - * then correct our initial guess. > > - */ > > - udev->ep0.desc.wMaxPacketSize = cpu_to_le16(64); > > - break; > > - case USB_SPEED_LOW: /* fixed at 8 */ > > - udev->ep0.desc.wMaxPacketSize = cpu_to_le16(8); > > - break; > > - default: > > - goto fail; > > - } > > + udev->ep0.desc.wMaxPacketSize = cpu_to_le16(64); > > + break; > > + case USB_SPEED_LOW: /* fixed at 8 */ > > + udev->ep0.desc.wMaxPacketSize = cpu_to_le16(8); > > + break; > > + default: > > + goto fail; > > } > > The usb_ep0_reinit() call belongs here, right after > udev->ep0.desc.wMaxPacketSize is set. > > > > > speed = usb_speed_string(udev->speed); > > @@ -5062,6 +5060,9 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1, > > goto fail; > > } > > > > + /* Sync the guessed ep0 maxpacket size to hardware if needed */ > > + usb_ep0_reinit(udev); > > Not here. And not inside the retry loop -- ep0_reinit should be > called only once since the maxpacket value is changed only once. Sashiko pointed out that xhci-hcd may not perform ep0_reinit() properly until address_device() or enable_device() is called. So it's either this kludge, or dependency on an xhci-hcd patch which didn't exist until today: https://lore.kernel.org/linux-usb/20261109112846.04bfeb0f.michal.pecio@gmail.com/ Regards, Michal