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Tue, 4 Jul 2023 19:00:12 +0300 (MSK) Received: from localhost (100.64.160.123) by p-i-exch-sc-m01.sberdevices.ru (172.16.192.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.30; Tue, 4 Jul 2023 19:00:01 +0300 Date: Tue, 4 Jul 2023 19:00:12 +0300 From: Dmitry Rokosov To: CC: , , , , , , , , , , , , , , , , Subject: Re: [PATCH v1 3/5] tty: serial: meson: apply ttyS devname instead of ttyAML for new SoCs Message-ID: <20230704160012.yoaqgk4plpyd6v26@CAB-WSD-L081021> References: <20230704135936.14697-1-ddrokosov@sberdevices.ru> <20230704135936.14697-4-ddrokosov@sberdevices.ru> <20230704145933.y3o3fhjj6q7df44d@CAB-WSD-L081021> <9fde3632-2419-d36b-9c54-337155bb482e@linaro.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <9fde3632-2419-d36b-9c54-337155bb482e@linaro.org> User-Agent: NeoMutt/20220415 X-Originating-IP: [100.64.160.123] X-ClientProxiedBy: p-i-exch-sc-m01.sberdevices.ru (172.16.192.107) To p-i-exch-sc-m01.sberdevices.ru (172.16.192.107) X-KSMG-Rule-ID: 10 X-KSMG-Message-Action: clean X-KSMG-AntiSpam-Lua-Profiles: 178428 [Jul 04 2023] X-KSMG-AntiSpam-Version: 5.9.59.0 X-KSMG-AntiSpam-Envelope-From: DDRokosov@sberdevices.ru X-KSMG-AntiSpam-Rate: 0 X-KSMG-AntiSpam-Status: not_detected X-KSMG-AntiSpam-Method: none X-KSMG-AntiSpam-Auth: dkim=none X-KSMG-AntiSpam-Info: LuaCore: 520 520 ccb018a655251011855942a2571029252d3d69a2, {Tracking_uf_ne_domains}, {Track_E25351}, {Tracking_from_domain_doesnt_match_to}, 100.64.160.123:7.1.2;127.0.0.199:7.1.2;sberdevices.ru:5.0.1,7.1.1;p-i-exch-sc-m01.sberdevices.ru:5.0.1,7.1.1;libera.irclog.whitequark.org:7.1.1;d41d8cd98f00b204e9800998ecf8427e.com:7.1.1, FromAlignment: s, {Tracking_white_helo}, ApMailHostAddress: 100.64.160.123 X-MS-Exchange-Organization-SCL: -1 X-KSMG-AntiSpam-Interceptor-Info: scan successful X-KSMG-AntiPhishing: Clean, bases: 2023/07/04 13:59:00 X-KSMG-LinksScanning: Clean, bases: 2023/07/04 13:58:00 X-KSMG-AntiVirus: Kaspersky Secure Mail Gateway, version 2.0.1.6960, bases: 2023/07/04 05:54:00 #21559896 X-KSMG-AntiVirus-Status: Clean, skipped X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230704_090017_040513_7A4234FB X-CRM114-Status: GOOD ( 44.01 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jul 04, 2023 at 05:29:57PM +0200, neil.armstrong@linaro.org wrote: > Hi. > > On 04/07/2023 16:59, Dmitry Rokosov wrote: > > Hello Neil, > > > > Thank you for quick feedback! > > > > On Tue, Jul 04, 2023 at 04:42:39PM +0200, neil.armstrong@linaro.org wrote: > > > On 04/07/2023 15:59, Dmitry Rokosov wrote: > > > > It is worth noting that the devname ttyS is a widely recognized tty name > > > > and is commonly used by many uart device drivers. Given the established > > > > usage and compatibility concerns, it may not be feasible to change the > > > > devname for older SoCs. However, for new definitions, it is acceptable > > > > and even recommended to use a new devname to help ensure clarity and > > > > avoid any potential conflicts on lower or upper software levels. In > > > > addition, modify the meson_uart_dt match data for g12a, a1, and s4 to > > > > their appropriate values to ensure proper devname values and > > > > functionality. > > > > > > I'm not confident about modifying a global struct from a probe, > > > I think you should add a separate meson_uart_driver/meson_serial_console couple > > > with ttyS instead of ttyAML, refer to the right uart_driver in meson_uart_data > > > and in probe() register it and pass it to uart_add_one_port(). > > > > Could you provide some insight into why you believe this solution may > > not be acceptable? It appears that the meson_uart_driver and > > meson_serial_console are not labeled with __init, which means it stay in > > memory forever. > Yes but nothing forbids registering a g12a and an a1 uart on the same system, > but you modify the meson_uart_driver/meson_serial_console struct. > This could cause some issues. > > In practice this will never happen, but since we don't control the DT passed > to the system we must make sure we take in account any scenario. > Yep, agree, this will cause an issue. > > > > To clarify, are you suggesting a solution that involves segregating the > > meson_uart_driver and meson_serial_console objects for each scenario and > > subsequently declaring pointers to both objects within the > > meson_uart_data? I want to make sure that I have accurately grasped the > > essence of your proposed approach. > > Not both, only the appropriate one. > > So either we make sure ttyAML and ttyS at exclusive at runtime, in this case we can > modify the global meson_uart_driver/meson_serial_console, or you add > a second set of uart_driver/console structs to handle this improbable case. Got it, thank you for explanation! I will prepare the v2. > > > > > > > > > > For more information please refer to IRC discussion at [1]. > > > > > > > > Links: > > > > [1]: https://libera.irclog.whitequark.org/linux-amlogic/2023-07-03 > > > > > > > > Signed-off-by: Dmitry Rokosov > > > > --- > > > > drivers/tty/serial/meson_uart.c | 33 +++++++++++++++++++++++++++++++-- > > > > 1 file changed, 31 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c > > > > index 87c0eb5f2dba..361f9326b527 100644 > > > > --- a/drivers/tty/serial/meson_uart.c > > > > +++ b/drivers/tty/serial/meson_uart.c > > > > @@ -82,6 +82,7 @@ static struct uart_driver meson_uart_driver; > > > > static struct uart_port *meson_ports[AML_UART_PORT_NUM]; > > > > struct meson_uart_data { > > > > + const char *dev_name; > > > > bool has_xtal_div2; > > > > }; > > > > @@ -683,6 +684,7 @@ static int meson_uart_probe_clocks(struct platform_device *pdev, > > > > static int meson_uart_probe(struct platform_device *pdev) > > > > { > > > > + const struct meson_uart_data *priv_data; > > > > struct resource *res_mem; > > > > struct uart_port *port; > > > > u32 fifosize = 64; /* Default is 64, 128 for EE UART_0 */ > > > > @@ -729,6 +731,18 @@ static int meson_uart_probe(struct platform_device *pdev) > > > > if (ret) > > > > return ret; > > > > + priv_data = device_get_match_data(&pdev->dev); > > > > + > > > > + if (priv_data) { > > > > + struct console *cons = meson_uart_driver.cons; > > > > + > > > > + meson_uart_driver.dev_name = priv_data->dev_name; > > > > + > > > > + if (cons) > > > > + strscpy(cons->name, priv_data->dev_name, > > > > + sizeof(cons->name)); > > > > + } > > > > + > > > > if (!meson_uart_driver.state) { > > > > ret = uart_register_driver(&meson_uart_driver); > > > > if (ret) > > > > @@ -748,7 +762,7 @@ static int meson_uart_probe(struct platform_device *pdev) > > > > port->x_char = 0; > > > > port->ops = &meson_uart_ops; > > > > port->fifosize = fifosize; > > > > - port->private_data = (void *)device_get_match_data(&pdev->dev); > > > > + port->private_data = (void *)priv_data; > > > > meson_ports[pdev->id] = port; > > > > platform_set_drvdata(pdev, port); > > > > @@ -780,6 +794,17 @@ static int meson_uart_remove(struct platform_device *pdev) > > > > } > > > > static struct meson_uart_data meson_g12a_uart_data = { > > > > + .dev_name = "ttyAML", > > > > + .has_xtal_div2 = true, > > > > +}; > > > > + > > > > +static struct meson_uart_data meson_a1_uart_data = { > > > > + .dev_name = "ttyS", > > > > + .has_xtal_div2 = false, > > > > +}; > > > > + > > > > +static struct meson_uart_data meson_s4_uart_data = { > > > > + .dev_name = "ttyS", > > > > .has_xtal_div2 = true, > > > > }; > > > > @@ -794,7 +819,11 @@ static const struct of_device_id meson_uart_dt_match[] = { > > > > }, > > > > { > > > > .compatible = "amlogic,meson-s4-uart", > > > > - .data = (void *)&meson_g12a_uart_data, > > > > + .data = (void *)&meson_s4_uart_data, > > > > + }, > > > > + { > > > > + .compatible = "amlogic,meson-a1-uart", > > > > + .data = (void *)&meson_a1_uart_data, > > > > }, > > > > { /* sentinel */ }, > > > > }; > > > > > > -- Thank you, Dmitry _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel