Re: [PATCH 4/8] tty: atmel_serial: prepare clk before calling enable

boris brezillon <b.brezillon@xxxxxxxxxxx> · Thu, 20 Jun 2013 10:06:44 +0200

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@xxxxxxxxxxx>

Acked-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>

(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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