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Message-ID: <5dae58ca-487a-cbd8-00f8-9951a425f70e@gmail.com>
Date: Thu, 2 Jun 2022 11:29:12 +0200
From: Richard Genoud <richard.genoud@...il.com>
To: Claudiu Beznea <claudiu.beznea@...rochip.com>,
gregkh@...uxfoundation.org, jirislaby@...nel.org,
nicolas.ferre@...rochip.com, alexandre.belloni@...tlin.com,
patrice.chotard@...s.st.com
Cc: linux-serial@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] tty: serial: atmel: improve clock management
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.
>
> Signed-off-by: Claudiu Beznea <claudiu.beznea@...rochip.com>
> ---
> 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
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