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 43C3D34D4CE; Thu, 9 Jul 2026 07:15:27 +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=1783581328; cv=none; b=Wm+pd02wQopL9dORvTvbPaCohnuPYxEj65I0eCvy0NUPZ2/mxMCyha6RnBmeg0qTm9ehHOgrTE3yTUPL923cVaaVIsIT1legdbCwsw/DWOUopEnwyrmrH6ta2p6gvBCzZwvMsc2WASx4ADcIH+75dgQR8DkMMXXwe5fSI9nwZXE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783581328; c=relaxed/simple; bh=WdSR441NKOMTKsasewYrtwHIN8OLgEjCQ1aBsApRgow=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=GsogM1hCX2eSEVkJkBFGOtZODgajc7uWeyNR50LcTnm87wRWmN18zYlDyZCJ3KioKKDgtbul91W2fSYKymjUh42uZaBBwa1x2875/dJGwrEkwOmYxULEdx17b85AZUBQujPSnHY1DrP51DTmUPrXN80ItCu79W4otrFHMQ0fOqg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=htJRnZ7G; 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="htJRnZ7G" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5FA681F000E9; Thu, 9 Jul 2026 07:15:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783581326; bh=cF0eVD5olzr1eYRO2KucDiaZmcLy/yJ6ot339dEMkHI=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=htJRnZ7G/gayHxDDXsbEZEUv+37vWfXZJgmGBsJx6pjIFjUoLEYvlbICG9oRhvxzy gMFHewt3aaQ5QjN2zvgFXqKBF/Mr7AShmql7rC1iBp51lxHCMw4p9PgbS1HnTRxzSE Ps/Nm1YTYlRY5nqMX/47tZt5LVq6sPBGHbHK4Pb4YYFUy+mNnd0EnMGp+MIdFkp8Ib zlLLlA2B5LxZr3dHEpneiH1XZ6EiShJS4ix6e8/u4QvzhC6h5GnoSXhv9iftPGrNpi 6MRbrMb65pdYXXXjK6uVX3gLoF4AGkz+eOminaQcgs6U83n7VNoKfCT1lzYn5ya+PU b+yZKrTF6hjdQ== Message-ID: Date: Thu, 9 Jul 2026 09:15:24 +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 v3 08/15] serial: 8250_mxpcie: speed up TX using memory-mapped FIFO window To: Crescent Hsieh , Greg Kroah-Hartman , Andy Shevchenko Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, FangpingFP.Cheng@moxa.com, Epson.Chiang@moxa.com References: <20260709053314.435629-1-crescentcy.hsieh@moxa.com> <20260709053314.435629-9-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 09. 07. 26, 7:33, Crescent Hsieh wrote: ... > --- a/drivers/tty/serial/8250/8250_mxpcie.c > +++ b/drivers/tty/serial/8250/8250_mxpcie.c ... > @@ -318,6 +320,37 @@ static u16 mxpcie8250_rx_chars(struct uart_8250_port *up, u16 lsr) > return serial8250_rx_chars(up, lsr); > } > > +static void mxpcie8250_tx_chars(struct uart_8250_port *up) > +{ > + struct uart_port *port = &up->port; > + struct tty_port *tport = &port->state->port; > + unsigned int count, txsize; > + unsigned char c; > + > + if (port->x_char) { > + uart_xchar_out(port, UART_TX); > + return; > + } > + if (uart_tx_stopped(port) || kfifo_is_empty(&tport->xmit_fifo)) { > + port->ops->stop_tx(port); > + return; > + } > + txsize = serial_in(up, MOXA_PUART_TX_FIFO_CNT); > + count = min(kfifo_len(&tport->xmit_fifo), port->fifosize - txsize); > + > + for (unsigned int i = 0; i < count; ++i) { > + if (!uart_fifo_get(port, &c)) > + break; > + > + serial_out(up, MOXA_PUART_TX_FIFO_MEM + i, c); > + } > + if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS) > + uart_write_wakeup(port); > + > + if (kfifo_is_empty(&tport->xmit_fifo) && !(up->capabilities & UART_CAP_RPM)) > + port->ops->stop_tx(port); What's the reason not to use uart_port_tx() et al.? thanks, -- js suse labs