From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 462AE23D7D1; Thu, 11 Sep 2025 12:28:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757593734; cv=none; b=rLNsM/QQbaB2vWd7Xx3bjeOdpki6fN5Rv7sxCJqFAaQ6JzicqrXzp2LasGCLN/5sUHc+crDtzbvryUQQgOWFGudzsI/DSfooIJ+Zpkiqzl2zGAMqaahufo8KnNeQ0lSlSAKLje+21D8PmXR/V30o7J+4I6aQU4OSjHXwe1BC2DA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757593734; c=relaxed/simple; bh=cOxH4L+r13ac6AWe2+G4yXqo8aVVu5wvCvByGl2iHkw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=fiQlX0A74OCsnv8FqoGwGVgc+ZWJ2ik0CHvTu3VVkGQSEFXogwUA4c4UO1fHLq6BOnq5yNN0gwQL8eqXKFIiHmPfEfpxhR/kiLcT/0KT2lMa+1UjKaaWXV2Et273p89nIzekYElpf+GrbTuwv1Rs4vp+u8UPlUxNfINNQ3juNnE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=UvOLrkMH; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="UvOLrkMH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6B913C4CEF0; Thu, 11 Sep 2025 12:28:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1757593733; bh=cOxH4L+r13ac6AWe2+G4yXqo8aVVu5wvCvByGl2iHkw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UvOLrkMHmOSr7Ireijjhav+ydIi780aZXaoV0O0BGMrOMxLn5+UvlKW9VbQhP6nmp IT9X8DURLQCtz20pPbCtJKvXAZa8yPAEVF9IRCwRVichVIxoBCirEECJHy8RpEUO2y 7YJS/JpEY661ATtGqNwBCLL+nw/XpHlDp+jl4ilQ= Date: Thu, 11 Sep 2025 14:28:51 +0200 From: Greg Kroah-Hartman To: Pin-yen Lin Cc: "Rafael J . Wysocki" , Len Brown , Pavel Machek , Danilo Krummrich , Saravana Kannan , Hsin-Te Yuan , linux-pm@vger.kernel.org, Chen-Yu Tsai , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/2] PM: sleep: Don't wait for SYNC_STATE_ONLY device links Message-ID: <2025091129-harmonics-clambake-6240@gregkh> References: <20250911112058.3610201-1-treapking@chromium.org> <20250911112058.3610201-2-treapking@chromium.org> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250911112058.3610201-2-treapking@chromium.org> On Thu, Sep 11, 2025 at 07:16:03PM +0800, Pin-yen Lin wrote: > Device links with DL_FLAG_SYNC_STATE_ONLY should not affect suspend > and resume, and functions like device_reorder_to_tail() and > device_link_add() doesn't try to reorder the consumers with such flag. > > However, dpm_wait_for_consumers() and dpm_wait_for_suppliers() doesn't > check this flag before triggering dpm_wait, leading to potential hang > during suspend/resume. > > This can be reproduced on MT8186 Corsola Chromebook with devicetree like: > > usb-a-connector { > compatible = "usb-a-connector"; > port { > usb_a_con: endpoint { > remote-endpoint = <&usb_hs>; > }; > }; > }; > > usb_host { > compatible = "mediatek,mt8186-xhci", "mediatek,mtk-xhci"; > port { > usb_hs: endpoint { > remote-endpoint = <&usb_a_con>; > }; > }; > }; > > In this case, the two nodes form a cycle and a SYNC_STATE_ONLY devlink > between usb_host (supplier) and usb-a-connector (consumer) is created. > > Use device_link_flag_is_sync_state_only() to check this in > dpm_wait_for_consumers() and dpm_wait_for_suppliers() to fix this. > > Fixes: 05ef983e0d65a ("driver core: Add device link support for SYNC_STATE_ONLY flag") > Signed-off-by: Pin-yen Lin > --- > > Changes in v2: > - Update commit message > - Use device_link_flag_is_sync_state_only() > > drivers/base/power/main.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c > index 2ea6e05e6ec9..73a1916170ae 100644 > --- a/drivers/base/power/main.c > +++ b/drivers/base/power/main.c > @@ -282,7 +282,8 @@ static void dpm_wait_for_suppliers(struct device *dev, bool async) > * walking. > */ > list_for_each_entry_rcu_locked(link, &dev->links.suppliers, c_node) > - if (READ_ONCE(link->status) != DL_STATE_DORMANT) > + if (READ_ONCE(link->status) != DL_STATE_DORMANT && > + !device_link_flag_is_sync_state_only(link->flags)) > dpm_wait(link->supplier, async); > > device_links_read_unlock(idx); > @@ -339,7 +340,8 @@ static void dpm_wait_for_consumers(struct device *dev, bool async) > * unregistration). > */ > list_for_each_entry_rcu_locked(link, &dev->links.consumers, s_node) > - if (READ_ONCE(link->status) != DL_STATE_DORMANT) > + if (READ_ONCE(link->status) != DL_STATE_DORMANT && > + !device_link_flag_is_sync_state_only(link->flags)) > dpm_wait(link->consumer, async); > > device_links_read_unlock(idx); The way you use this new function does not require it to have been exported to modules :( thanks, greg k-h