Re: [PATCH v5 1/2] can: tcan4x5x: reset device before register access

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Sean

On 12/11/19 7:45 AM, Sean Nyekjaer wrote:


On 11/12/2019 14.39, Dan Murphy wrote:
Sean

On 12/11/19 7:39 AM, Sean Nyekjaer wrote:
It's a good idea to reset a ip-block/spi device before using it, this
patch will reset the device.

And a generic reset function if needed elsewhere.

Signed-off-by: Sean Nyekjaer <sean@xxxxxxxxxx>
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
---
Changes since v3:
  - added reset if the reset_gpio is not avaliable

Changes since v4:
  - added error handling for the SPI I/O

  drivers/net/can/m_can/tcan4x5x.c | 29 +++++++++++++++++++++++++++--
  1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/m_can/tcan4x5x.c b/drivers/net/can/m_can/tcan4x5x.c
index b6b2feca9e8f..032d110e0870 100644
--- a/drivers/net/can/m_can/tcan4x5x.c
+++ b/drivers/net/can/m_can/tcan4x5x.c
@@ -166,6 +166,27 @@ static void tcan4x5x_check_wake(struct tcan4x5x_priv *priv)
      }
  }
+static int tcan4x5x_reset(struct tcan4x5x_priv *priv)
+{
+    int ret = 0;
+
+    if (priv->reset_gpio) {
+        gpiod_set_value(priv->reset_gpio, 1);
+
+        /* tpulse_width minimum 30us */
+        usleep_range(30, 100);
+        gpiod_set_value(priv->reset_gpio, 0);
+    } else {
+        ret = regmap_write(priv->regmap, TCAN4X5X_CONFIG, TCAN4X5X_SW_RESET);
+        if (ret)
+            return ret;
+    }
+
+    usleep_range(700, 1000);
+
+    return ret;
+}
+
  static int regmap_spi_gather_write(void *context, const void *reg,
                     size_t reg_len, const void *val,
                     size_t val_len)
@@ -351,6 +372,7 @@ static int tcan4x5x_disable_wake(struct m_can_classdev *cdev)
  static int tcan4x5x_parse_config(struct m_can_classdev *cdev)
  {
      struct tcan4x5x_priv *tcan4x5x = cdev->device_data;
+    int ret;
      tcan4x5x->device_wake_gpio = devm_gpiod_get(cdev->dev, "device-wake",
                              GPIOD_OUT_HIGH);
@@ -363,10 +385,13 @@ static int tcan4x5x_parse_config(struct m_can_classdev *cdev)       tcan4x5x->reset_gpio = devm_gpiod_get_optional(cdev->dev, "reset",
                                 GPIOD_OUT_LOW);
-    if (IS_ERR(tcan4x5x->reset_gpio))
+    if (IS_ERR(tcan4x5x->reset_gpio)) {
          tcan4x5x->reset_gpio = NULL;
+    }

Why did you add brackets?

This is not needed for single statement if's

Oh just legacy from V4... V6 then ...

I went back to v4 this was not a change in that version.

Dan




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