[PATCH 2/3] tty: serial: atmel: improve clock management
Richard Genoud
richard.genoud at gmail.com
Fri Jun 10 06:43:15 PDT 2022
Hi,
Le 08/06/2022 à 10:18, Claudiu.Beznea at 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 <claudiu.beznea at microchip.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
>
More information about the linux-arm-kernel
mailing list