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 3E029C433FE for ; Tue, 15 Nov 2022 16:15:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238407AbiKOQPA (ORCPT ); Tue, 15 Nov 2022 11:15:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35628 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229624AbiKOQO5 (ORCPT ); Tue, 15 Nov 2022 11:14:57 -0500 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 85F261D673; Tue, 15 Nov 2022 08:14:56 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1668528896; x=1700064896; h=date:from:to:cc:subject:in-reply-to:message-id: references:mime-version; bh=75pgIdVKQNQqHUWCvgs9DIXphPFBaaKB0XR/iHS+Qbk=; b=YyPREz725oBax5FrOZP6xsMsABZGiLGlDA9VNTH2Z1Y6xFzsSSCRmaZE 8fG9NczKUCSczLd8Y0Liz7ZY5U/RLrrDFANKH4OLYfUvlmjnHO0JWls7R H8rhIcl5JUDdfwJKoXBI7uJGtjCyn/D16zU+TStQkIi8xX30RGVHQWBJz DxHe3ui0jRJ58h6txcgyopoKORuVK74oJT8MOM+rCGPinn2XnjQWnYyJ/ v4b+iIQbPc0RgAHge5X6SiQ9UtgNfMjiD+/oD65QvQdHk+kgPHV4fW3J9 E1Ohnn/N1bfAY3SbNjssxH/Wp4Arnv68kYdgumGjqOLUu/NBEEHbdh79v Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10532"; a="339091821" X-IronPort-AV: E=Sophos;i="5.96,166,1665471600"; d="scan'208";a="339091821" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Nov 2022 08:14:55 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10532"; a="781393695" X-IronPort-AV: E=Sophos;i="5.96,166,1665471600"; d="scan'208";a="781393695" Received: from mrosso-mobl1.ger.corp.intel.com ([10.249.45.244]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Nov 2022 08:14:52 -0800 Date: Tue, 15 Nov 2022 18:14:50 +0200 (EET) From: =?ISO-8859-15?Q?Ilpo_J=E4rvinen?= To: Gabriel Somlo cc: LKML , linux-serial , Greg Kroah-Hartman , Jiri Slaby , kgugala@antmicro.com, mholenko@antmicro.com, joel@jms.id.au, david.abdurachmanov@gmail.com, florent@enjoy-digital.fr, geert@linux-m68k.org Subject: Re: [PATCH v3 13/14] serial: liteuart: add IRQ support for the TX path In-Reply-To: <20221112212125.448824-14-gsomlo@gmail.com> Message-ID: <957056a1-78a5-1141-18d7-b49f87fa85f0@linux.intel.com> References: <20221112212125.448824-1-gsomlo@gmail.com> <20221112212125.448824-14-gsomlo@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 12 Nov 2022, Gabriel Somlo wrote: > Modify the TX path to operate in an IRQ-compatible way, while > maintaining support for polling mode via the poll timer. > > Signed-off-by: Gabriel Somlo > --- > drivers/tty/serial/liteuart.c | 67 ++++++++++++++++++++++++----------- > 1 file changed, 47 insertions(+), 20 deletions(-) > > diff --git a/drivers/tty/serial/liteuart.c b/drivers/tty/serial/liteuart.c > index e30adb30277f..307c27398e30 100644 > --- a/drivers/tty/serial/liteuart.c > +++ b/drivers/tty/serial/liteuart.c > @@ -46,6 +46,7 @@ struct liteuart_port { > struct uart_port port; > struct timer_list timer; > u32 id; > + bool poll_tx_started; > }; > > #define to_liteuart_port(port) container_of(port, struct liteuart_port, port) > @@ -78,29 +79,24 @@ static void liteuart_putchar(struct uart_port *port, unsigned char ch) > > static void liteuart_stop_tx(struct uart_port *port) > { > - /* not used in LiteUART, but called unconditionally from serial_core */ Drop this comment from the earlier patch too given you remove it here. It just adds useless churn in diff for no useful reason. > + if (port->irq) { > + u8 irq_mask = litex_read8(port->membase + OFF_EV_ENABLE); > + litex_write8(port->membase + OFF_EV_ENABLE, irq_mask & ~EV_TX); If you put irq_mask into liteuart_port you wouldn't need to read it back here? > + } else { > + struct liteuart_port *uart = to_liteuart_port(port); > + uart->poll_tx_started = false; > + } > } > > static void liteuart_start_tx(struct uart_port *port) > { > - struct circ_buf *xmit = &port->state->xmit; > - unsigned char ch; > - > - if (unlikely(port->x_char)) { > - litex_write8(port->membase + OFF_RXTX, port->x_char); > - port->icount.tx++; > - port->x_char = 0; > - } else if (!uart_circ_empty(xmit)) { > - while (xmit->head != xmit->tail) { > - ch = xmit->buf[xmit->tail]; > - xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); > - port->icount.tx++; This is not based on tty-next tree. Please rebase on top of it (you might have noted it already, IIRC, somebody noted uart_xmit_advance conflict in some patch, perhaps it was you :-)). > - liteuart_putchar(port, ch); > - } > + if (port->irq) { > + u8 irq_mask = litex_read8(port->membase + OFF_EV_ENABLE); > + litex_write8(port->membase + OFF_EV_ENABLE, irq_mask | EV_TX); ->irq_mask? > + } else { > + struct liteuart_port *uart = to_liteuart_port(port); > + uart->poll_tx_started = true; > } > - > - if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) > - uart_write_wakeup(port); > } > > static void liteuart_stop_rx(struct uart_port *port) > @@ -131,18 +127,47 @@ static void liteuart_rx_chars(struct uart_port *port) > tty_flip_buffer_push(&port->state->port); > } > > +static void liteuart_tx_chars(struct uart_port *port) > +{ > + struct circ_buf *xmit = &port->state->xmit; > + > + if (unlikely(port->x_char)) { > + litex_write8(port->membase + OFF_RXTX, port->x_char); > + port->x_char = 0; > + port->icount.tx++; > + return; > + } > + > + while (!litex_read8(port->membase + OFF_TXFULL)) { > + if (xmit->head == xmit->tail) There exists a helper for this condition. > + break; > + litex_write8(port->membase + OFF_RXTX, xmit->buf[xmit->tail]); > + xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); > + port->icount.tx++; uart_xmit_advance() > + } > + > + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) > + uart_write_wakeup(port); > + > + if (uart_circ_empty(xmit)) > + liteuart_stop_tx(port); > +} You might want to check if you can generate this whole function with Jiri's tx helpers (IIRC, they're only in tty-next tree currently). > + > static irqreturn_t liteuart_interrupt(int irq, void *data) > { > struct liteuart_port *uart = data; > struct uart_port *port = &uart->port; > u8 isr = litex_read8(port->membase + OFF_EV_PENDING); > > - /* for now, only rx path triggers interrupts */ > - isr &= EV_RX; > + if (!(port->irq || uart->poll_tx_started)) > + isr &= ~EV_TX; /* polling mode with tx stopped */ > > spin_lock(&port->lock); > if (isr & EV_RX) > liteuart_rx_chars(port); > + if (isr & EV_TX) { > + liteuart_tx_chars(port); > + } Extra braces. > spin_unlock(&port->lock); > > return IRQ_RETVAL(isr); > @@ -196,6 +221,7 @@ static int liteuart_startup(struct uart_port *port) > } > > if (!port->irq) { > + uart->poll_tx_started = false; Can poll_tx_started ever be true here? > timer_setup(&uart->timer, liteuart_timer, 0); > mod_timer(&uart->timer, jiffies + uart_poll_timeout(port)); > } > @@ -210,6 +236,7 @@ static void liteuart_shutdown(struct uart_port *port) > struct liteuart_port *uart = to_liteuart_port(port); > > litex_write8(port->membase + OFF_EV_ENABLE, 0); > + uart->poll_tx_started = false; > > if (port->irq) > free_irq(port->irq, port); > -- i.