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Message-ID: <51C2B814.4050308@overkiz.com>
Date: Thu, 20 Jun 2013 10:06:44 +0200
From: boris brezillon <b.brezillon@...rkiz.com>
To: Nicolas Ferre <nicolas.ferre@...el.com>
CC: Ludovic Desroches <ludovic.desroches@...el.com>,
Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jslaby@...e.cz>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-serial@...r.kernel.org
Subject: Re: [PATCH 4/8] tty: atmel_serial: prepare clk before calling enable
On 20/06/2013 09:48, Nicolas Ferre wrote:
> On 19/06/2013 13:17, Boris BREZILLON :
>> Replace clk_enable/disable with clk_prepare_enable/disable_unprepare to
>> avoid common clk framework warnings.
>>
>> Signed-off-by: Boris BREZILLON <b.brezillon@...rkiz.com>
>
> Acked-by: Nicolas Ferre <nicolas.ferre@...el.com>
>
> (one comment though)
>
>> ---
>> drivers/tty/serial/atmel_serial.c | 41
>> ++++++++++++++++++++++++++++---------
>> 1 file changed, 31 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/tty/serial/atmel_serial.c
>> b/drivers/tty/serial/atmel_serial.c
>> index 3467462..691265f 100644
>> --- a/drivers/tty/serial/atmel_serial.c
>> +++ b/drivers/tty/serial/atmel_serial.c
>> @@ -1100,7 +1100,7 @@ static void atmel_serial_pm(struct uart_port
>> *port, unsigned int state,
>> * Enable the peripheral clock for this serial port.
>> * This is called on uart_open() or a resume event.
>> */
>> - clk_enable(atmel_port->clk);
>> + clk_prepare_enable(atmel_port->clk);
>
> Do we need to check return code here?
We could, but the pm function will not reflect the failure (void return).
In addition, the clk_prepare_enable should not fail because it already
succeed in the probe
function (no memory allocation, simple bit masking in clk-peripheral
implem).
I can add it add this check (and avoid the interrrupt activation if it
fails) if you want.
>
>>
>> /* re-enable interrupts if we disabled some on suspend */
>> UART_PUT_IER(port, atmel_port->backup_imr);
>> @@ -1114,7 +1114,7 @@ static void atmel_serial_pm(struct uart_port
>> *port, unsigned int state,
>> * Disable the peripheral clock for this serial port.
>> * This is called on uart_close() or a suspend event.
>> */
>> - clk_disable(atmel_port->clk);
>> + clk_disable_unprepare(atmel_port->clk);
>> break;
>> default:
>> printk(KERN_ERR "atmel_serial: unknown pm %d\n", state);
>> @@ -1458,9 +1458,10 @@ static void atmel_of_init_port(struct
>> atmel_uart_port *atmel_port,
>> /*
>> * Configure the port from the platform device resource info.
>> */
>> -static void atmel_init_port(struct atmel_uart_port *atmel_port,
>> +static int atmel_init_port(struct atmel_uart_port *atmel_port,
>> struct platform_device *pdev)
>> {
>> + int ret;
>> struct uart_port *port = &atmel_port->uart;
>> struct atmel_uart_data *pdata = pdev->dev.platform_data;
>>
>> @@ -1496,9 +1497,19 @@ static void atmel_init_port(struct
>> atmel_uart_port *atmel_port,
>> /* for console, the clock could already be configured */
>> if (!atmel_port->clk) {
>> atmel_port->clk = clk_get(&pdev->dev, "usart");
>> - clk_enable(atmel_port->clk);
>> + 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(atmel_port->clk);
>> + clk_disable_unprepare(atmel_port->clk);
>> /* only enable clock when USART is in use */
>> }
>>
>> @@ -1511,6 +1522,8 @@ static void atmel_init_port(struct
>> atmel_uart_port *atmel_port,
>> } else {
>> atmel_port->tx_done_mask = ATMEL_US_TXRDY;
>> }
>> +
>> + return 0;
>> }
>>
>> struct platform_device *atmel_default_console_device; /* the
>> serial console device */
>> @@ -1601,6 +1614,7 @@ static void __init
>> atmel_console_get_options(struct uart_port *port, int *baud,
>>
>> static int __init atmel_console_setup(struct console *co, char
>> *options)
>> {
>> + int ret;
>> struct uart_port *port = &atmel_ports[co->index].uart;
>> int baud = 115200;
>> int bits = 8;
>> @@ -1612,7 +1626,9 @@ static int __init atmel_console_setup(struct
>> console *co, char *options)
>> return -ENODEV;
>> }
>>
>> - clk_enable(atmel_ports[co->index].clk);
>> + ret = clk_prepare_enable(atmel_ports[co->index].clk);
>> + if (ret)
>> + return ret;
>>
>> UART_PUT_IDR(port, -1);
>> UART_PUT_CR(port, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);
>> @@ -1645,6 +1661,7 @@ static struct console atmel_console = {
>> */
>> static int __init atmel_console_init(void)
>> {
>> + int ret;
>> if (atmel_default_console_device) {
>> struct atmel_uart_data *pdata =
>> atmel_default_console_device->dev.platform_data;
>> @@ -1655,7 +1672,9 @@ static int __init atmel_console_init(void)
>> port->uart.line = id;
>>
>> add_preferred_console(ATMEL_DEVICENAME, id, NULL);
>> - atmel_init_port(port, atmel_default_console_device);
>> + ret = atmel_init_port(port, atmel_default_console_device);
>> + if (ret)
>> + return ret;
>> register_console(&atmel_console);
>> }
>>
>> @@ -1786,7 +1805,9 @@ static int atmel_serial_probe(struct
>> platform_device *pdev)
>> port->backup_imr = 0;
>> port->uart.line = ret;
>>
>> - atmel_init_port(port, pdev);
>> + ret = atmel_init_port(port, pdev);
>> + if (ret)
>> + goto err;
>>
>> pinctrl = devm_pinctrl_get_select_default(&pdev->dev);
>> if (IS_ERR(pinctrl)) {
>> @@ -1812,9 +1833,9 @@ static int atmel_serial_probe(struct
>> platform_device *pdev)
>> && ATMEL_CONSOLE_DEVICE->flags & CON_ENABLED) {
>> /*
>> * The serial core enabled the clock for us, so undo
>> - * the clk_enable() in atmel_console_setup()
>> + * the clk_prepare_enable() in atmel_console_setup()
>> */
>> - clk_disable(port->clk);
>> + clk_disable_unprepare(port->clk);
>> }
>> #endif
>>
>>
>
>
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