From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753356AbdBHEHz (ORCPT ); Tue, 7 Feb 2017 23:07:55 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:58358 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751094AbdBHEHw (ORCPT ); Tue, 7 Feb 2017 23:07:52 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 2D3906072D Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=timur@codeaurora.org Subject: Re: [PATCH 2/2] tty: pl011: Work around QDF2400 E44 for earlycon To: Christopher Covington , Jonathan Corbet , Marc Zyngier , Catalin Marinas , Will Deacon , linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Mark Rutland , linux-kernel@vger.kernel.org, shankerd@codeaurora.org, Russell King , Greg Kroah-Hartman , Jiri Slaby , linux-serial@vger.kernel.org Cc: Mark Langsdorf , Mark Salter , Jon Masters , Neil Leeder References: <20170208005736.18724-1-cov@codeaurora.org> <20170208005736.18724-2-cov@codeaurora.org> From: Timur Tabi Message-ID: <35007ccc-678d-0e2a-109b-4b5321c4fbff@codeaurora.org> Date: Tue, 7 Feb 2017 22:07:54 -0600 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:49.0) Gecko/20100101 Firefox/49.0 SeaMonkey/2.46 MIME-Version: 1.0 In-Reply-To: <20170208005736.18724-2-cov@codeaurora.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Christopher Covington wrote: > The previous change worked around QDF2432v1 and QDF2400v1 SoC erratum 44 > for the full-fledged console, when UART AMBA Port (UAP) data is available. > Additionally provide a workaround the earlycon case, again checking TXFE == > 0 instead of BUSY == 1. As earlycon is operating before UAP data is > available, the implementation is different than in the preceding patch. > > Signed-off-by: Christopher Covington > --- > drivers/tty/serial/amba-pl011.c | 28 +++++++++++++++++++++++++++- > 1 file changed, 27 insertions(+), 1 deletion(-) > > diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c > index 41e51901d6ef..f25e7c994f8e 100644 > --- a/drivers/tty/serial/amba-pl011.c > +++ b/drivers/tty/serial/amba-pl011.c > @@ -2411,6 +2411,29 @@ static bool qdf2400_e44(void) { > cpu_var_model == MIDR_QCOM_FALKOR_V1); > } > > +#ifdef CONFIG_QCOM_QDF2400_ERRATUM_44 > +static void qdf2400_e44_putc(struct uart_port *port, int c) > +{ > + while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF) > + cpu_relax(); > + if (port->iotype == UPIO_MEM32) > + writel(c, port->membase + UART01x_DR); > + else > + writeb(c, port->membase + UART01x_DR); I believe 32-bit writes are safe on QDF2400v1, so I think you technically don't need the UPIO_MEM32 check. Just always call writel. > + while (!(readl(port->membase + UART01x_FR) & UART011_FR_TXFE)) > + cpu_relax(); > +} > + > +static void qdf2400_e44_early_write(struct console *con, const char *s, unsigned n) > +{ > + struct earlycon_device *dev = con->data; > + > + uart_console_write(&dev->port, s, n, qdf2400_e44_putc); > +} > +#else > +#define qdf2400_e44_early_write pl011_early_write > +#endif Same with patch 1/2. If you change qdf2400_e44(), you don't need the #else block. > + > static void pl011_putc(struct uart_port *port, int c) > { > while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF) > @@ -2436,7 +2459,10 @@ static int __init pl011_early_console_setup(struct earlycon_device *device, > if (!device->port.membase) > return -ENODEV; > > - device->con->write = pl011_early_write; > + if (qdf2400_e44()) > + device->con->write = qdf2400_e44_early_write; > + else > + device->con->write = pl011_early_write; > return 0; > } > OF_EARLYCON_DECLARE(pl011, "arm,pl011", pl011_early_console_setup); -- Sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation.