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([2a01:e0a:181:90d0:6ce1:d6aa:6a23:353b]) by smtp.gmail.com with ESMTPSA id s13-20020a5d6a8d000000b0020c5253d8f7sm27652541wru.67.2022.06.10.06.43.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 10 Jun 2022 06:43:16 -0700 (PDT) Message-ID: Date: Fri, 10 Jun 2022 15:43:15 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Subject: Re: [PATCH 2/3] tty: serial: atmel: improve clock management Content-Language: en-US To: Claudiu.Beznea@microchip.com, gregkh@linuxfoundation.org, jirislaby@kernel.org, Nicolas.Ferre@microchip.com, alexandre.belloni@bootlin.com, patrice.chotard@foss.st.com Cc: linux-serial@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20220525133733.1051714-1-claudiu.beznea@microchip.com> <20220525133733.1051714-3-claudiu.beznea@microchip.com> <5dae58ca-487a-cbd8-00f8-9951a425f70e@gmail.com> <4a189186-9871-09ab-d7e1-9346f7af0bfe@microchip.com> From: Richard Genoud In-Reply-To: <4a189186-9871-09ab-d7e1-9346f7af0bfe@microchip.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Le 08/06/2022 à 10:18, Claudiu.Beznea@microchip.com a écrit : > Hi, > > On 02.06.2022 12:29, Richard Genoud wrote: >> >> Hi, >> >> Le 25/05/2022 à 15:37, Claudiu Beznea a écrit : >>> atmel_port->clk was requested in atmel_init_port() (which is called only >>> on probe path) only if atmel_port->clk was NULL. But atmel_port->clk is >>> NULL on probing path. Thus don't check this. Along with this the clock is >>> now requested with devm_clk_get() and the clock request has been moved in >>> atmel_serial_probe() function to avoid disabling/re-enabling it on probe >>> path for multiple times. All the checks of atmel_port->clk were removed >>> along with clk_put() and atmel_port->clk = NULL. Now, on probing time the >>> clock is enabled at the beginning and disabled at the end of probe. As >>> atmel_console_setup() is called in the middle of probe and clock is >>> already enabled at that time the clk_prepare_enable() in >>> atmel_console_setup() has also been removed. >> Could you split this patch into smaller steps ? >> I think it will be easier to read and review. > > I kept it as a single patch as it is all related to clock management. > > Having the clock enabled only at the beginning of probe and disabled at the > end of probe lead to removing the code in atmel_init_port(), also removing > the code under CONFIG_SERIAL_ATMEL_CONSOLE in probe. Same for the rest of > the removed code. > > With this, would you still want to split it in multiple patches? I think that, at least, the switch from clk_get() to devm_clk_get() can be in a separate patch. But in general, I prefer when patches are self-explaining rather than a bigger patch with a longer explanation of what it does in the commit message. Regards, Richard > > Thank you, > Claudiu Beznea >>> >>> Signed-off-by: Claudiu Beznea >>> --- >>>   drivers/tty/serial/atmel_serial.c | 65 +++++++------------------------ >>>   1 file changed, 15 insertions(+), 50 deletions(-) >>> >>> diff --git a/drivers/tty/serial/atmel_serial.c >>> b/drivers/tty/serial/atmel_serial.c >>> index 5c793a23dc54..2955b1012014 100644 >>> --- a/drivers/tty/serial/atmel_serial.c >>> +++ b/drivers/tty/serial/atmel_serial.c >>> @@ -2501,24 +2501,7 @@ static int atmel_init_port(struct atmel_uart_port >>> *atmel_port, >>>       if (ret) >>>               return ret; >>> >>> -     /* for console, the clock could already be configured */ >>> -     if (!atmel_port->clk) { >>> -             atmel_port->clk = clk_get(&mpdev->dev, "usart"); >>> -             if (IS_ERR(atmel_port->clk)) { >>> -                     ret = PTR_ERR(atmel_port->clk); >>> -                     atmel_port->clk = NULL; >>> -                     return ret; >>> -             } >>> -             ret = clk_prepare_enable(atmel_port->clk); >>> -             if (ret) { >>> -                     clk_put(atmel_port->clk); >>> -                     atmel_port->clk = NULL; >>> -                     return ret; >>> -             } >>> -             port->uartclk = clk_get_rate(atmel_port->clk); >>> -             clk_disable_unprepare(atmel_port->clk); >>> -             /* only enable clock when USART is in use */ >>> -     } >>> +     port->uartclk = clk_get_rate(atmel_port->clk); >>> >>>       /* >>>        * Use TXEMPTY for interrupt when rs485 or ISO7816 else TXRDY or >>> @@ -2640,10 +2623,6 @@ static int __init atmel_console_setup(struct >>> console *co, char *options) >>>               return -ENODEV; >>>       } >>> >>> -     ret = clk_prepare_enable(atmel_ports[co->index].clk); >>> -     if (ret) >>> -             return ret; >>> - >> Now, "int ret;" is unused, you can remove it. >> >>>       atmel_uart_writel(port, ATMEL_US_IDR, -1); >>>       atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | >>> ATMEL_US_RSTRX); >>>       atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN | ATMEL_US_RXEN); >>> @@ -2889,14 +2868,23 @@ static int atmel_serial_probe(struct >>> platform_device *pdev) >>>       atomic_set(&atmel_port->tasklet_shutdown, 0); >>>       spin_lock_init(&atmel_port->lock_suspended); >>> >>> +     atmel_port->clk = devm_clk_get(&pdev->dev, "usart"); >>> +     if (IS_ERR(atmel_port->clk)) { >>> +             ret = PTR_ERR(atmel_port->clk); >>> +             goto err; >>> +     } >>> +     ret = clk_prepare_enable(atmel_port->clk); >>> +     if (ret) >>> +             goto err; >>> + >>>       ret = atmel_init_port(atmel_port, pdev); >>>       if (ret) >>> -             goto err_clear_bit; >>> +             goto err_clk_disable_unprepare; >>> >>>       atmel_port->gpios = mctrl_gpio_init(&atmel_port->uart, 0); >>>       if (IS_ERR(atmel_port->gpios)) { >>>               ret = PTR_ERR(atmel_port->gpios); >>> -             goto err_clear_bit; >>> +             goto err_clk_disable_unprepare; >>>       } >>> >>>       if (!atmel_use_pdc_rx(&atmel_port->uart)) { >>> @@ -2905,7 +2893,7 @@ static int atmel_serial_probe(struct >>> platform_device *pdev) >>>                                    sizeof(struct atmel_uart_char), >>>                                    GFP_KERNEL); >>>               if (!data) >>> -                     goto err_alloc_ring; >>> +                     goto err_clk_disable_unprepare; >>>               atmel_port->rx_ring.buf = data; >>>       } >>> >>> @@ -2915,26 +2903,9 @@ static int atmel_serial_probe(struct >>> platform_device *pdev) >>>       if (ret) >>>               goto err_add_port; >>> >>> -#ifdef CONFIG_SERIAL_ATMEL_CONSOLE >>> -     if (uart_console(&atmel_port->uart) >>> -                     && ATMEL_CONSOLE_DEVICE->flags & CON_ENABLED) { >>> -             /* >>> -              * The serial core enabled the clock for us, so undo >>> -              * the clk_prepare_enable() in atmel_console_setup() >>> -              */ >>> -             clk_disable_unprepare(atmel_port->clk); >>> -     } >>> -#endif >>> - >>>       device_init_wakeup(&pdev->dev, 1); >>>       platform_set_drvdata(pdev, atmel_port); >>> >>> -     /* >>> -      * The peripheral clock has been disabled by atmel_init_port(): >>> -      * enable it before accessing I/O registers >>> -      */ >>> -     clk_prepare_enable(atmel_port->clk); >>> - >>>       if (rs485_enabled) { >>>               atmel_uart_writel(&atmel_port->uart, ATMEL_US_MR, >>>                                 ATMEL_US_USMODE_NORMAL); >>> @@ -2958,12 +2929,8 @@ static int atmel_serial_probe(struct >>> platform_device *pdev) >>>   err_add_port: >>>       kfree(atmel_port->rx_ring.buf); >>>       atmel_port->rx_ring.buf = NULL; >>> -err_alloc_ring: >>> -     if (!uart_console(&atmel_port->uart)) { >>> -             clk_put(atmel_port->clk); >>> -             atmel_port->clk = NULL; >>> -     } >>> -err_clear_bit: >>> +err_clk_disable_unprepare: >>> +     clk_disable_unprepare(atmel_port->clk); >>>       clear_bit(atmel_port->uart.line, atmel_ports_in_use); >>>   err: >>>       return ret; >>> @@ -2997,8 +2964,6 @@ static int atmel_serial_remove(struct >>> platform_device *pdev) >>> >>>       clear_bit(port->line, atmel_ports_in_use); >>> >>> -     clk_put(atmel_port->clk); >>> -     atmel_port->clk = NULL; >>>       pdev->dev.of_node = NULL; >>> >>>       return ret; >> Thanks ! >> >> Regards, >> Richard >