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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2FDEEC43334 for ; Mon, 27 Jun 2022 11:54:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238140AbiF0LyX (ORCPT ); Mon, 27 Jun 2022 07:54:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55942 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238871AbiF0Lwp (ORCPT ); Mon, 27 Jun 2022 07:52:45 -0400 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3382BDED1; Mon, 27 Jun 2022 04:46:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1656330370; x=1687866370; h=date:from:to:cc:subject:in-reply-to:message-id: references:mime-version; bh=038ViQj4OdJMOtsCH8E05gcJKrV6mUvMiaaLGQCFo14=; b=MvkWEbVLP4mP0s/WkY4CK3hUeVibF9JQOL1q//3tHt7oe0kp0XhjemPe uhldW23mIg8276oH2EvSTE0xtBRz++DwKc+/dcUzjRFcecnJ9dMd625zH 6IgQeT62GkxAjWQst3gGQCKoZ0a3+FNTaDCt3KDGxi5VZf6bwclut4tfe GIBFG+qb2ToII8wlRzONuJ3uL8fPMtLKl+/rMn4cMffJNwCvD+mgFs9kf kZ8qDr38+9wvwU6ubU/uBi6VyP6t5cLVZBDHA8ArOXgpIJC88oX4SN6Og F+eEUxAgr3EDoBEcL55V/fFpVf+1VMQYAfUKxXbSxgBbn+WRX/Tjz4AQU Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10390"; a="278973156" X-IronPort-AV: E=Sophos;i="5.92,226,1650956400"; d="scan'208";a="278973156" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jun 2022 04:46:09 -0700 X-IronPort-AV: E=Sophos;i="5.92,226,1650956400"; d="scan'208";a="646396113" Received: from gretavix-mobl3.amr.corp.intel.com ([10.249.43.78]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jun 2022 04:46:07 -0700 Date: Mon, 27 Jun 2022 14:46:07 +0300 (EEST) From: =?ISO-8859-15?Q?Ilpo_J=E4rvinen?= To: Chanho Park cc: Krzysztof Kozlowski , Greg Kroah-Hartman , Jiri Slaby , Alim Akhtar , Hector Martin , Jaewon Kim , Vincent Whitchurch , linux-samsung-soc@vger.kernel.org, linux-serial , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] tty: serial: samsung_tty: loopback mode support In-Reply-To: <20220627032353.8868-1-chanho61.park@samsung.com> Message-ID: References: <20220627032353.8868-1-chanho61.park@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-samsung-soc@vger.kernel.org On Mon, 27 Jun 2022, Chanho Park wrote: > Internal loopback mode can be supported by setting > S3C2443_UCON_LOOPBACK bit. The mode & bit can be supported since > s3c2410 and later SoCs. In that case, why is the LOOPBACK define named 2443 and not 2410??? The change looks fine otherwise. I note though that many of the current drivers won't return TOICM_LOOP from ->get_mctrl() but I don't think it's exactly wrong to return it either. Perhaps lack of returning it is due to Documentation/driver-api/serial/driver.rst not including TOICM_LOOP in get_mctrl's list of information but only in set_mctrl's one. -- i. > We can test it by linux-serial-test program[1] > with -k option. It will set TIOCM_LOOP mode during test. > > -k, --loopback Use internal hardware loop back > > [1]: https://github.com/cbrake/linux-serial-test > Signed-off-by: Chanho Park > --- > drivers/tty/serial/samsung_tty.c | 19 ++++++++++++++++--- > 1 file changed, 16 insertions(+), 3 deletions(-) > > diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c > index d5ca904def34..d7d035cd95c0 100644 > --- a/drivers/tty/serial/samsung_tty.c > +++ b/drivers/tty/serial/samsung_tty.c > @@ -1002,16 +1002,22 @@ static unsigned int s3c24xx_serial_tx_empty(struct uart_port *port) > static unsigned int s3c24xx_serial_get_mctrl(struct uart_port *port) > { > unsigned int umstat = rd_reg(port, S3C2410_UMSTAT); > + unsigned int ucon = rd_reg(port, S3C2410_UCON); > + unsigned int mctrl = TIOCM_CAR | TIOCM_DSR; > > if (umstat & S3C2410_UMSTAT_CTS) > - return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS; > - else > - return TIOCM_CAR | TIOCM_DSR; > + mctrl |= TIOCM_CTS; > + > + if (ucon & S3C2443_UCON_LOOPBACK) > + mctrl |= TIOCM_LOOP; > + > + return mctrl; > } > > static void s3c24xx_serial_set_mctrl(struct uart_port *port, unsigned int mctrl) > { > unsigned int umcon = rd_regl(port, S3C2410_UMCON); > + unsigned int ucon = rd_reg(port, S3C2410_UCON); > > if (mctrl & TIOCM_RTS) > umcon |= S3C2410_UMCOM_RTS_LOW; > @@ -1019,6 +1025,13 @@ static void s3c24xx_serial_set_mctrl(struct uart_port *port, unsigned int mctrl) > umcon &= ~S3C2410_UMCOM_RTS_LOW; > > wr_regl(port, S3C2410_UMCON, umcon); > + > + if (mctrl & TIOCM_LOOP) > + ucon |= S3C2443_UCON_LOOPBACK; > + else > + ucon &= ~S3C2443_UCON_LOOPBACK; > + > + wr_regl(port, S3C2410_UCON, ucon); > } > > static void s3c24xx_serial_break_ctl(struct uart_port *port, int break_state) >