From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DB0B5C7EE23 for ; Mon, 5 Jun 2023 13:18:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=KhPAl5xRdDjhvHLhx4jX5pXoXFnxVRNqx5piaWbjIDw=; b=MUU1uDqiX21JA0ngq+Jyt5+y4Q lUPXFyrKJ2kOVfPdu0eeo/kopqoKAEIQI6o0mJufAqa3uKXziewnddvdN/c4gNrL9TKWQI4Hnx0uU EyPf3KCrvxXCZmWK7pu7Sd0iZWJLbU2mg2v1KgBL2zpPpoEU0U4K/UGc6y9ycWB8agQQ82hcTdX4x 9aI2q83T9uJmiF4xK4zOPf5uESSfO39CRp2h+DX10SH7YXsT5SNy/PXgpw9Nb1wI2RZBbn24tUkVU /RNfFpO+5kd9u9J1tPObaBeDTVHqrYawyMcM9mtnFPlUag1GsT34SE/ua+vUwndUaKL7VLxmAAzfe kNlPGzAg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q6A64-00FaLQ-1K; Mon, 05 Jun 2023 13:18:08 +0000 Received: from muru.com ([72.249.23.125]) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q6A61-00FaKl-1U for linux-mediatek@lists.infradead.org; Mon, 05 Jun 2023 13:18:06 +0000 Received: from localhost (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTPS id 9C03080FE; Mon, 5 Jun 2023 13:18:04 +0000 (UTC) Date: Mon, 5 Jun 2023 16:18:03 +0300 From: Tony Lindgren To: Chen-Yu Tsai Cc: John Ogness , Greg Kroah-Hartman , Jiri Slaby , Andy Shevchenko , Dhruva Gole , Ilpo =?utf-8?B?SsOkcnZpbmVu?= , Johan Hovold , Sebastian Andrzej Siewior , Vignesh Raghavendra , linux-omap@vger.kernel.org, Andy Shevchenko , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, =?utf-8?B?TsOtY29sYXMgRi4gUi4gQS4=?= Prado , AngeloGioacchino Del Regno , linux-mediatek@lists.infradead.org Subject: Re: [PATCH v12 1/1] serial: core: Start managing serial controllers to enable runtime PM Message-ID: <20230605131803.GA14287@atomide.com> References: <20230525113034.46880-1-tony@atomide.com> <20230602083335.GA181647@google.com> <87a5xii33r.fsf@jogness.linutronix.de> <20230603054139.GR14287@atomide.com> <20230603063533.GS14287@atomide.com> <20230605061511.GW14287@atomide.com> <20230605122447.GY14287@atomide.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230605_061805_540145_750173CC X-CRM114-Status: GOOD ( 37.23 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org * Chen-Yu Tsai [230605 13:01]: > On Mon, Jun 5, 2023 at 8:24 PM Tony Lindgren wrote: > > > > * Chen-Yu Tsai [230605 11:34]: > > > On Mon, Jun 5, 2023 at 2:15 PM Tony Lindgren wrote: > > > > diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c > > > > --- a/drivers/tty/serial/8250/8250_mtk.c > > > > +++ b/drivers/tty/serial/8250/8250_mtk.c > > > > @@ -425,11 +439,10 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios, > > > > static int __maybe_unused mtk8250_runtime_suspend(struct device *dev) > > > > { > > > > struct mtk8250_data *data = dev_get_drvdata(dev); > > > > - struct uart_8250_port *up = serial8250_get_port(data->line); > > > > > > > > /* wait until UART in idle status */ > > > > while > > > > - (serial_in(up, MTK_UART_DEBUG0)); > > > > + (mtk8250_read(data, MTK_UART_DEBUG0)); > > > > > > I believe it still gets stuck here sometimes. > > > > Hmm so maybe you need to mtk8250_write(data, 0, MTK_UART_RATE_FIX) in > > probe before pm_runtime_resume_and_get() that enables the baud clock? > > That's something I changed, so maybe it messes up things. > > I think it has something to do with the do_pm() function calling > the callbacks directly, then also calling runtime PM. Yeah I'm not following really what's going on there.. So then I guess the call for mtk8250_write(data, 0, MTK_UART_RATE_FIX) should be after the pm_runtime_resume_and_get() call. > > Looking at the 8250_mtk git log, it's runtime PM functions seem to only > > currently manage the baud clock so register access should be doable > > without runtime PM resume? > > Actually it only manages the bus clock. The baud clock is simply the system > XTAL which is not gateble. OK > > > With your earlier patch, it could get through registering the port, and > > > the console would show > > > > > > 11002000.serial: ttyS0 at MMIO 0x11002000 (irq = 240, base_baud = > > > 1625000) is a ST16650V2 > > > > > > for the console UART. > > > > OK > > > > > Angelo mentioned that we should be using SLEEP_REQ/SLEEP_ACK registers > > > in the MTK UART hardware. > > > > > > I tried reworking it into your patch here, but it causes issues with the > > > UART-based Bluetooth on one of my devices. After the UART runtime suspends > > > and resumes, something is off and causes the transfers during Bluetooth > > > init to become corrupt. > > > > > > I'll try some more stuff, but the existing code seems timing dependent. > > > If I add too many printk statements to the runtime suspend/resume > > > callbacks, things seem to work. One time I even ended up with broken > > > UARTs but otherwise booted up the system. > > > > Well another thing that now changes is that we now runtime suspend the > > port at the end of the probe. What the 8250_mtk probe was doing earlier > > it was leaving the port baud clock enabled, but runtime PM disabled > > until mtk8250_do_pm() I guess. > > I guess that's the biggest difference? Since the *bus* clock gets disabled, > any access will hang. Is it enough to just support runtime PM? Or do I have > to also have UART_CAP_RPM? Maybe try changing pm_runtime_put_sync() at the end of the probe to just pm_runtime_put_noidle()? Then the driver should be back to where it was with clocks enabled but runtime PM suspended. I don't think you need UART_CAP_RPM right now unless 8250_mtk adds support for autosuspend. That stuff will get replaced by the serial_core generic PM patch from Andy. I think in it's current form 8250_mtk just gets enabled when the port is opened, and disabled when the port is closed. And gets disabled for system suspend. Regards, Tony