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 X-Spam-Level: X-Spam-Status: No, score=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,LOTS_OF_MONEY,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6FF44C43331 for ; Thu, 26 Mar 2020 02:02:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2FAE720737 for ; Thu, 26 Mar 2020 02:02:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=micronovasrl.com header.i=@micronovasrl.com header.b="gyaVhkVV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727595AbgCZCCm (ORCPT ); Wed, 25 Mar 2020 22:02:42 -0400 Received: from mail.micronovasrl.com ([212.103.203.10]:56350 "EHLO mail.micronovasrl.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727600AbgCZCCm (ORCPT ); Wed, 25 Mar 2020 22:02:42 -0400 Received: from mail.micronovasrl.com (mail.micronovasrl.com [127.0.0.1]) by mail.micronovasrl.com (Postfix) with ESMTP id 305CEB02EB5 for ; Thu, 26 Mar 2020 03:02:41 +0100 (CET) Authentication-Results: mail.micronovasrl.com (amavisd-new); dkim=pass reason="pass (just generated, assumed good)" header.d=micronovasrl.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=micronovasrl.com; h=content-transfer-encoding:content-language:content-type :content-type:in-reply-to:mime-version:user-agent:date:date :message-id:from:from:references:to:subject:subject; s=dkim; t= 1585188160; x=1586052161; bh=dN/heXYHaTVt9oKxd/kcQsTKZ2AS/ViFWmy ++nUgKTc=; b=gyaVhkVVoF1dOQwG5ciV1RHXB2e780qpTqkeqKX2gaA3CipiGnR PxSh+83ZZIqfE4YNHjv2/h8zQpdb7D10ddxfV80w4NeLGvljU+qxYRELR5dLwBq/ 2Xv852WSlJTDpqV5ClnYySDBXimM2SCpuX60rW8hWP9HNVhkYSKZvYEY= X-Virus-Scanned: Debian amavisd-new at mail.micronovasrl.com Received: from mail.micronovasrl.com ([127.0.0.1]) by mail.micronovasrl.com (mail.micronovasrl.com [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id XN_P5sn7HJMB for ; Thu, 26 Mar 2020 03:02:40 +0100 (CET) Received: from [10.212.134.200] (unknown [192.168.123.254]) by mail.micronovasrl.com (Postfix) with ESMTPSA id A4912B02E4E; Thu, 26 Mar 2020 03:02:39 +0100 (CET) Subject: Re: [PATCH v2 4/7] serial: 8250: Handle implementations not having TEMT interrupt using em485 To: =?UTF-8?Q?Heiko_St=c3=bcbner?= Cc: gregkh@linuxfoundation.org, jslaby@suse.com, andriy.shevchenko@linux.intel.com, matwey.kornilov@gmail.com, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, lukas@wunner.de, christoph.muellner@theobroma-systems.com References: <20200325231422.1502366-1-heiko@sntech.de> <20200325231422.1502366-5-heiko@sntech.de> <3a5df648-b054-3338-f7a4-4c01783eabf6@micronovasrl.com> <12195570.sTQbgxCmNy@diego> From: Giulio Benetti Message-ID: Date: Thu, 26 Mar 2020 03:02:39 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <12195570.sTQbgxCmNy@diego> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Language: it Content-Transfer-Encoding: 8bit Sender: linux-serial-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org Hi Heiko, Il 26/03/2020 01:05, Heiko Stübner ha scritto: > Hi Giulio, > > Am Donnerstag, 26. März 2020, 00:47:38 CET schrieb Giulio Benetti: >> very cleaner way to handle TEMT as a capability! >> And I've found one thing... >> >> Il 26/03/2020 00:14, Heiko Stuebner ha scritto: >>> From: Giulio Benetti >>> >>> Some 8250 ports have a TEMT interrupt but it's not a part of the 8250 >>> standard, instead only available on some implementations. >>> >>> The current em485 implementation does not work on ports without it. >>> The only chance to make it work is to loop-read on LSR register. >>> >>> So add UART_CAP_TEMT to mark 8250 uarts having this interrupt, >>> update all current em485 users with that capability and make >>> the stop_tx function loop-read on uarts not having it. >>> >>> Signed-off-by: Giulio Benetti >>> [moved to use added UART_CAP_TEMT, use readx_poll_timeout] >>> Signed-off-by: Heiko Stuebner >>> --- >>> drivers/tty/serial/8250/8250.h | 1 + >>> drivers/tty/serial/8250/8250_bcm2835aux.c | 2 +- >>> drivers/tty/serial/8250/8250_of.c | 2 ++ >>> drivers/tty/serial/8250/8250_omap.c | 2 +- >>> drivers/tty/serial/8250/8250_port.c | 25 +++++++++++++++++++---- >>> 5 files changed, 26 insertions(+), 6 deletions(-) >>> >>> diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h >>> index 52bb21205bb6..770eb00db497 100644 >>> --- a/drivers/tty/serial/8250/8250.h >>> +++ b/drivers/tty/serial/8250/8250.h >>> @@ -82,6 +82,7 @@ struct serial8250_config { >>> #define UART_CAP_MINI (1 << 17) /* Mini UART on BCM283X family lacks: >>> * STOP PARITY EPAR SPAR WLEN5 WLEN6 >>> */ >>> +#define UART_CAP_TEMT (1 << 18) /* UART has TEMT interrupt */ >>> >>> #define UART_BUG_QUOT (1 << 0) /* UART has buggy quot LSB */ >>> #define UART_BUG_TXEN (1 << 1) /* UART has buggy TX IIR status */ >>> diff --git a/drivers/tty/serial/8250/8250_bcm2835aux.c b/drivers/tty/serial/8250/8250_bcm2835aux.c >>> index 12d03e678295..3881242424ca 100644 >>> --- a/drivers/tty/serial/8250/8250_bcm2835aux.c >>> +++ b/drivers/tty/serial/8250/8250_bcm2835aux.c >>> @@ -91,7 +91,7 @@ static int bcm2835aux_serial_probe(struct platform_device *pdev) >>> return -ENOMEM; >>> >>> /* initialize data */ >>> - up.capabilities = UART_CAP_FIFO | UART_CAP_MINI; >>> + up.capabilities = UART_CAP_FIFO | UART_CAP_MINI | UART_CAP_TEMT; >>> up.port.dev = &pdev->dev; >>> up.port.regshift = 2; >>> up.port.type = PORT_16550; >>> diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c >>> index 65e9045dafe6..841f6fcb2878 100644 >>> --- a/drivers/tty/serial/8250/8250_of.c >>> +++ b/drivers/tty/serial/8250/8250_of.c >>> @@ -225,6 +225,8 @@ static int of_platform_serial_probe(struct platform_device *ofdev) >>> &port8250.overrun_backoff_time_ms) != 0) >>> port8250.overrun_backoff_time_ms = 0; >>> >>> + port8250.capabilities |= UART_CAP_TEMT; >>> + >> >> Shouldn't this be NOT UART_CAP_TEMT set by default? On all other >> vendor specific files you enable it, I think here you shouldn't enable >> it too by default. Right? > > 8250_of does use the em485 emulation - see of_platform_serial_setup() > So I did go by the lazy assumption that any 8250 driver using rs485 > before my series always used the interrupt driver code path, so > implicitly required to have the TEMT interrupt. > > Of course, you're right that with the 8250_of maybe not all variants > actually do have this interrupt, so falling back to the polling here might > be safer. Probably here it's worth introducing a dt boolean property like "temt-capability", then you set or not UART_CAP_TEMT according to its presence in dts. This way all cases are covered and we can act completely through dts files. What about that? Best regards -- Giulio Benetti CTO MICRONOVA SRL Sede: Via A. Niedda 3 - 35010 Vigonza (PD) Tel. 049/8931563 - Fax 049/8931346 Cod.Fiscale - P.IVA 02663420285 Capitale Sociale ¤ 26.000 i.v. Iscritta al Reg. Imprese di Padova N. 02663420285 Numero R.E.A. 258642