From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 E116532ED3A; Thu, 30 Jul 2026 05:49:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785390595; cv=none; b=pmcXNqEMa9c2WvsnAQnx9mlq4kof2qj+FtVnKOOHAUCN6mGzVJFaIp/xWNSMutPZ4YfQDkmxr1+dY5RreyhL6lU0LxRUbFUNCEiJKS9e6aEKyr2IDYJJJwUgCby/0gc/trv7uUHyVYdiP/jWlP27bRmzIqDQE6tMg0rLbqXn1nQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785390595; c=relaxed/simple; bh=L5OlKOGonYLda5FedjM33T4BZvXL6e+L8Cxt0+IOpqg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=kkPSR9tcqweuX8mFMe/qBdsh5bpMJWYPgp11j6kt/mcywYF0bIG2+YDkfpHUQ3etRmJiy6LszxHuG8P+iASQeLfHGTxWHNORwYZR/i1US+xAlZwf8MAqBB4jbKTDS5+3hCtpoBBGcSdCy9ktvBYTxYrDH7RTr7YY6JenQdhACT0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GULkMyuE; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="GULkMyuE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4DCC41F000E9; Thu, 30 Jul 2026 05:49:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785390594; bh=tKA1qT4g+rLJRWBX4pdd62gjNJBehqiiwoW1GWrwqZc=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=GULkMyuEcG6EB2uPqj9NBBQZi3ioCU1hcBCIglU6vKm16CknDCUgaAWj34G5whPT8 XjMwx7pgLa3YQ2Cfp8qnMO1Lal22sVGACPjclE5q2PmElxlZ+zEAl5ZHyGJKgRzeWi RHmgeL9YY9ftSimhnPgNN/cUKshIStD5mIb8yqvZJyVxVWUwewph0xtJk5UJSihxeZ HP6MvzVfxkKR6kqsvmRJ33dm77hqT823h2W13A+Kj3mUhB8MgnMwHph1vL4rJSL8g2 5DcvYh0aBDPSRJ2Nn0mCa/XP5knl1qUg1OPBnRIMyIpLbjdQeujAzjrQBsqM3BwRFB VZ8apwBKbxM3Q== Message-ID: <82cb09bd-7f95-4cb8-9cd9-634dbcf38729@kernel.org> Date: Thu, 30 Jul 2026 07:49:43 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 05/14] serial: 8250_mxpcie: offload XON/XOFF flow control to MUEx50 hardware To: Crescent Hsieh , Greg Kroah-Hartman , Andy Shevchenko Cc: FangpingFP.Cheng@moxa.com, Epson.Chiang@moxa.com, EddieSY.Lin@moxa.com, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org References: <20260729060602.492430-1-crescentcy.hsieh@moxa.com> <20260729060602.492430-6-crescentcy.hsieh@moxa.com> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 29. 07. 26, 8:05, Crescent Hsieh wrote: > The MUEx50 UART can handle in-band software flow control (XON/XOFF) > directly in hardware. > > Program the on-chip XON/XOFF characters from termios settings and enable > the corresponding MUEx50 flow control modes when IXON or IXOFF is > requested. Provide throttle and unthrottle callbacks so RX can be > stopped and resumed cleanly. > > Signed-off-by: Crescent Hsieh > --- > drivers/tty/serial/8250/8250_mxpcie.c | 55 +++++++++++++++++++++++++-- > 1 file changed, 52 insertions(+), 3 deletions(-) > > diff --git a/drivers/tty/serial/8250/8250_mxpcie.c b/drivers/tty/serial/8250/8250_mxpcie.c > index 1124c7d951b3..0517caaf2d26 100644 > --- a/drivers/tty/serial/8250/8250_mxpcie.c > +++ b/drivers/tty/serial/8250/8250_mxpcie.c ...> @@ -172,6 +184,23 @@ static void mxpcie8250_set_termios(struct uart_port *port, > efr |= (MOXA_PUART_EFR_AUTO_RTS | MOXA_PUART_EFR_AUTO_CTS); > up->port.status |= (UPSTAT_AUTORTS | UPSTAT_AUTOCTS); > } > + /* Set on-chip software flow control character */ > + serial_out(up, MOXA_PUART_XON1, START_CHAR(tty)); > + serial_out(up, MOXA_PUART_XON2, START_CHAR(tty)); > + serial_out(up, MOXA_PUART_XOFF1, STOP_CHAR(tty)); > + serial_out(up, MOXA_PUART_XOFF2, STOP_CHAR(tty)); > + > + efr &= ~(MOXA_PUART_EFR_RX_FLOW_MASK | MOXA_PUART_EFR_TX_FLOW_MASK); This is not needed, as you use FIELD_MODIFY(), right? > + val = I_IXON(tty) ? MOXA_PUART_EFR_RX_FLOW_XON1_XOFF1 : MOXA_PUART_EFR_RX_FLOW_DISABLED; > + efr = FIELD_MODIFY(MOXA_PUART_EFR_RX_FLOW_MASK, &efr, val); > + > + val = I_IXOFF(tty) ? MOXA_PUART_EFR_TX_FLOW_XON1_XOFF1 : MOXA_PUART_EFR_TX_FLOW_DISABLED; > + efr = FIELD_MODIFY(MOXA_PUART_EFR_TX_FLOW_MASK, &efr, val); Assigning back to efr is unnecessary. The reg is updated in-place. thanks, -- js suse labs