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 307FB4654F; Mon, 1 Apr 2024 16:47:27 +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=1711990047; cv=none; b=UpMb+2XAAyHo1Q9aIxkK4LXsK4jgxaRtFigFMKR9Wd9dj6HLve33DXnzqeyWKCoO1ApNHwOzURUiqDf+mFQ9TH/UbSdevRLXAOqQrMDioFCfqvFNx5n0JoIKDEm88vsA+8E5cw4VNWhAMTVUVsAqGN0gOS4YrWyjPTNXRCbaFB0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711990047; c=relaxed/simple; bh=U55rpLUd5IKxxvTLX5YJRbbjt1nOpFOD+oH48cnchR4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=cUOrvQqVVdnqfM+Ad82h8/Ad+UmxeKW7Ptq/vUEKWXcWn/bHQiS+1HkcYEBph+T/7fBhZPPmRIXR7wF5ujMkkXA4w07i97xV22bhJJv2qXv5oubxmHu+UMsQ1nICGt7XWgOriB+jRGHVC1Ey5TTEmD+hLB2rMiJstjXW88ZFBV8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ZyqcZlOO; 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="ZyqcZlOO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9DEC9C433F1; Mon, 1 Apr 2024 16:47:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1711990047; bh=U55rpLUd5IKxxvTLX5YJRbbjt1nOpFOD+oH48cnchR4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZyqcZlOOiH2jCW0KjxaYg/wavgBuT4ZnNzzGavxaFnN5TDG5e+WrVJd/tSHxly0B0 1nCC6RIeLa5YYKuhbx5KlrDM8rHRFHCajseYEeODSmjTFmGntfiUbELWgDKvZy6woD y7/DJu+f0Pj1uN9je5w21UyIskwsddQ7qWpFFnYA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Tony Lindgren , Andy Shevchenko , Yicong Yang Subject: [PATCH 6.6 230/396] serial: port: Dont suspend if the port is still busy Date: Mon, 1 Apr 2024 17:44:39 +0200 Message-ID: <20240401152554.775881151@linuxfoundation.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240401152547.867452742@linuxfoundation.org> References: <20240401152547.867452742@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yicong Yang commit 43066e32227ecde674e8ae1fcdd4a1ede67680c2 upstream. We accidently met the issue that the bash prompt is not shown after the previous command done and until the next input if there's only one CPU (In our issue other CPUs are isolated by isolcpus=). Further analysis shows it's because the port entering runtime suspend even if there's still pending chars in the buffer and the pending chars will only be processed in next device resuming. We are using amba-pl011 and the problematic flow is like below: Bash                                         kworker tty_write()   file_tty_write()     n_tty_write()       uart_write()         __uart_start()           pm_runtime_get() // wakeup waker             queue_work()                                     pm_runtime_work()                                                rpm_resume()                                                 status = RPM_RESUMING                                                 serial_port_runtime_resume()                                                   port->ops->start_tx()                                                     pl011_tx_chars()                                                       uart_write_wakeup()         […]         __uart_start()           pm_runtime_get() < 0 // because runtime status = RPM_RESUMING                                // later data are not commit to the port driver                                                 status = RPM_ACTIVE                                                 rpm_idle() -> rpm_suspend() This patch tries to fix this by checking the port busy before entering runtime suspending. A runtime_suspend callback is added for the port driver. When entering runtime suspend the callback is invoked, if there's still pending chars in the buffer then flush the buffer. Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM") Cc: stable Reviewed-by: Tony Lindgren Reviewed-by: Andy Shevchenko Signed-off-by: Yicong Yang Link: https://lore.kernel.org/r/20240226152351.40924-1-yangyicong@huawei.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_port.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) --- a/drivers/tty/serial/serial_port.c +++ b/drivers/tty/serial/serial_port.c @@ -46,8 +46,31 @@ out: return 0; } +static int serial_port_runtime_suspend(struct device *dev) +{ + struct serial_port_device *port_dev = to_serial_base_port_device(dev); + struct uart_port *port = port_dev->port; + unsigned long flags; + bool busy; + + if (port->flags & UPF_DEAD) + return 0; + + uart_port_lock_irqsave(port, &flags); + busy = __serial_port_busy(port); + if (busy) + port->ops->start_tx(port); + uart_port_unlock_irqrestore(port, flags); + + if (busy) + pm_runtime_mark_last_busy(dev); + + return busy ? -EBUSY : 0; +} + static DEFINE_RUNTIME_DEV_PM_OPS(serial_port_pm, - NULL, serial_port_runtime_resume, NULL); + serial_port_runtime_suspend, + serial_port_runtime_resume, NULL); static int serial_port_probe(struct device *dev) {