From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753994AbbLOMkp (ORCPT ); Tue, 15 Dec 2015 07:40:45 -0500 Received: from foss.arm.com ([217.140.101.70]:48452 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753829AbbLOMkn (ORCPT ); Tue, 15 Dec 2015 07:40:43 -0500 Message-ID: <56700A45.3070109@arm.com> Date: Tue, 15 Dec 2015 12:40:37 +0000 From: Vladimir Murzin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Andy Shevchenko CC: Arnd Bergmann , Russell King , Greg Kroah-Hartman , Daniel Lezcano , Thomas Gleixner , =?UTF-8?B?VXdlIEtsZWluZS1Lw7ZuaWc=?= , =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= , Maxime Coquelin , Mark Rutland , Pawel Moll , ijc+devicetree , Kumar Gala , Jiri Slaby , Rob Herring , devicetree , "linux-serial@vger.kernel.org" , "linux-api@vger.kernel.org" , linux-arm Mailing List , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v1 04/10] serial: mps2-uart: add MPS2 UART driver References: <1449048790-25859-1-git-send-email-vladimir.murzin@arm.com> <1449048790-25859-5-git-send-email-vladimir.murzin@arm.com> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/12/15 23:39, Andy Shevchenko wrote: > On Wed, Dec 2, 2015 at 11:33 AM, Vladimir Murzin > wrote: >> This driver adds support to the UART controller found on ARM MPS2 >> platform. > > Just few comments (have neither time not big desire to do full review). > Still better than nothing ;) I'm mostly agree on points you had, so I've just left some I'm doubt about... >> + >> +static void mps2_uart_enable_ms(struct uart_port *port) >> +{ >> +} >> + >> +static void mps2_uart_break_ctl(struct uart_port *port, int ctl) >> +{ >> +} > > Are those required to be present? If not, remove them until you have > alive code there. A quick grep shows that core calls mps2_uart_break_ctl() unconditionally, but, yes, it checks for presence of mps2_uart_enable_ms() before jumping there, so it is safe to remove latter. >> +static irqreturn_t mps2_uart_oerrirq(int irq, void *data) >> +{ >> + irqreturn_t handled = IRQ_NONE; >> + struct uart_port *port = data; >> + u8 irqflag = mps2_uart_read8(port, UARTn_INT); >> + >> + spin_lock(&port->lock); >> + >> + if (irqflag & UARTn_INT_RX_OVERRUN) { >> + struct tty_port *tport = &port->state->port; >> + >> + mps2_uart_write8(port, UARTn_INT_RX_OVERRUN, UARTn_INT); >> + tty_insert_flip_char(tport, 0, TTY_OVERRUN); >> + port->icount.overrun++; >> + handled = IRQ_HANDLED; >> + } >> + >> + /* XXX: this shouldn't happen? */ > > If shouldn't why it's there? Otherwise better to explain which > conditions may lead to this. > In practice I've never seen that happened and I think it never *should* happen since we check if there is room in TX buffer. However, I could be wrong here, so it is why that statement has question mark. >> + if (irqflag & UARTn_INT_TX_OVERRUN) { >> + mps2_uart_write8(port, UARTn_INT_TX_OVERRUN, UARTn_INT); >> + handled = IRQ_HANDLED; >> + } >> + >> + spin_unlock(&port->lock); >> + >> + return handled; >> +} >> + ... >> +static void mps2_uart_release_port(struct uart_port *port) >> +{ >> +} >> + >> +static int mps2_uart_request_port(struct uart_port *port) >> +{ >> + return 0; >> +} >> + > > Same question about empty stubs. Looks like they called unconditionally by the core. >> +static int __init mps2_uart_init(void) >> +{ >> + int ret; >> + >> + ret = uart_register_driver(&mps2_uart_driver); >> + if (ret) >> + return ret; >> + >> + ret = platform_driver_register(&mps2_serial_driver); >> + if (ret) >> + uart_unregister_driver(&mps2_uart_driver); >> + >> + pr_info("MPS2 UART driver initialized\n"); >> + >> + return ret; >> +} >> +module_init(mps2_uart_init); >> + >> +static void __exit mps2_uart_exit(void) >> +{ >> + platform_driver_unregister(&mps2_serial_driver); >> + uart_unregister_driver(&mps2_uart_driver); >> +} >> +module_exit(mps2_uart_exit); > > module_platform_driver(); > And move uart_*register calls to probe/remove. > With this move we'll get uart_*register for every device probed, no? Thanks Vladimir From mboxrd@z Thu Jan 1 00:00:00 1970 From: vladimir.murzin@arm.com (Vladimir Murzin) Date: Tue, 15 Dec 2015 12:40:37 +0000 Subject: [PATCH v1 04/10] serial: mps2-uart: add MPS2 UART driver In-Reply-To: References: <1449048790-25859-1-git-send-email-vladimir.murzin@arm.com> <1449048790-25859-5-git-send-email-vladimir.murzin@arm.com> Message-ID: <56700A45.3070109@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 12/12/15 23:39, Andy Shevchenko wrote: > On Wed, Dec 2, 2015 at 11:33 AM, Vladimir Murzin > wrote: >> This driver adds support to the UART controller found on ARM MPS2 >> platform. > > Just few comments (have neither time not big desire to do full review). > Still better than nothing ;) I'm mostly agree on points you had, so I've just left some I'm doubt about... >> + >> +static void mps2_uart_enable_ms(struct uart_port *port) >> +{ >> +} >> + >> +static void mps2_uart_break_ctl(struct uart_port *port, int ctl) >> +{ >> +} > > Are those required to be present? If not, remove them until you have > alive code there. A quick grep shows that core calls mps2_uart_break_ctl() unconditionally, but, yes, it checks for presence of mps2_uart_enable_ms() before jumping there, so it is safe to remove latter. >> +static irqreturn_t mps2_uart_oerrirq(int irq, void *data) >> +{ >> + irqreturn_t handled = IRQ_NONE; >> + struct uart_port *port = data; >> + u8 irqflag = mps2_uart_read8(port, UARTn_INT); >> + >> + spin_lock(&port->lock); >> + >> + if (irqflag & UARTn_INT_RX_OVERRUN) { >> + struct tty_port *tport = &port->state->port; >> + >> + mps2_uart_write8(port, UARTn_INT_RX_OVERRUN, UARTn_INT); >> + tty_insert_flip_char(tport, 0, TTY_OVERRUN); >> + port->icount.overrun++; >> + handled = IRQ_HANDLED; >> + } >> + >> + /* XXX: this shouldn't happen? */ > > If shouldn't why it's there? Otherwise better to explain which > conditions may lead to this. > In practice I've never seen that happened and I think it never *should* happen since we check if there is room in TX buffer. However, I could be wrong here, so it is why that statement has question mark. >> + if (irqflag & UARTn_INT_TX_OVERRUN) { >> + mps2_uart_write8(port, UARTn_INT_TX_OVERRUN, UARTn_INT); >> + handled = IRQ_HANDLED; >> + } >> + >> + spin_unlock(&port->lock); >> + >> + return handled; >> +} >> + ... >> +static void mps2_uart_release_port(struct uart_port *port) >> +{ >> +} >> + >> +static int mps2_uart_request_port(struct uart_port *port) >> +{ >> + return 0; >> +} >> + > > Same question about empty stubs. Looks like they called unconditionally by the core. >> +static int __init mps2_uart_init(void) >> +{ >> + int ret; >> + >> + ret = uart_register_driver(&mps2_uart_driver); >> + if (ret) >> + return ret; >> + >> + ret = platform_driver_register(&mps2_serial_driver); >> + if (ret) >> + uart_unregister_driver(&mps2_uart_driver); >> + >> + pr_info("MPS2 UART driver initialized\n"); >> + >> + return ret; >> +} >> +module_init(mps2_uart_init); >> + >> +static void __exit mps2_uart_exit(void) >> +{ >> + platform_driver_unregister(&mps2_serial_driver); >> + uart_unregister_driver(&mps2_uart_driver); >> +} >> +module_exit(mps2_uart_exit); > > module_platform_driver(); > And move uart_*register calls to probe/remove. > With this move we'll get uart_*register for every device probed, no? Thanks Vladimir