[PATCH] can: flexcan: Deferred on Regulator return EPROBE_DEFER

[PATCH] can: flexcan: Deferred on Regulator return EPROBE_DEFER

[Andreas Werner]

Return EPROBE_DEFER if Regulator returns EPROBE_DEFER

If the Flexcan driver is built into kernel and a regulator is used to
enable the CAN transceiver, the Flexcan driver may not use the regulator.

When initializing the Flexcan device with a regulator defined in the device
tree, but not initialized, the regulator subsystem returns EPROBE_DEFER, hence
the Flexcan init fails.

The solution for this is to return EPROBE_DEFER if regulator is not initialized
and wait until the regulator is initialized.

Signed-off-by: Andreas Werner <kernel@andy89.org>
---
I tested this Patch on a self made Freescale Vybrid VF610 board we developed in
the Formula Student Team of the UaS RheinMain. I think this Patch is working on
all other SoC with a Flexcan Controller. I tested it with the head rev of
linux-can and linux 3.19.2.

Since this is my first patch for the Linux Kernel, please tell me if
there are formal
failures.
---
 drivers/net/can/flexcan.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index b1d583b..c575163 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -1164,11 +1164,19 @@ static int flexcan_probe(struct platform_device *pdev)
     void __iomem *base;
     int err, irq;
     u32 clock_freq = 0;
+    struct regulator *reg_xceiver = NULL;

     if (pdev->dev.of_node)
         of_property_read_u32(pdev->dev.of_node,
                         "clock-frequency", &clock_freq);

+    reg_xceiver = devm_regulator_get(&pdev->dev, "xceiver");
+    if (PTR_ERR(reg_xceiver) == -EPROBE_DEFER) {
+        return -EPROBE_DEFER;
+    } else if (IS_ERR(reg_xceiver)) {
+        reg_xceiver = NULL;
+    }
+
     if (!clock_freq) {
         clk_ipg = devm_clk_get(&pdev->dev, "ipg");
         if (IS_ERR(clk_ipg)) {
@@ -1225,10 +1233,7 @@ static int flexcan_probe(struct platform_device *pdev)
     priv->clk_per = clk_per;
     priv->pdata = dev_get_platdata(&pdev->dev);
     priv->devtype_data = devtype_data;
-
-    priv->reg_xceiver = devm_regulator_get(&pdev->dev, "xceiver");
-    if (IS_ERR(priv->reg_xceiver))
-        priv->reg_xceiver = NULL;
+    priv->reg_xceiver = reg_xceiver;

     netif_napi_add(dev, &priv->napi, flexcan_poll, FLEXCAN_NAPI_WEIGHT);

-- 
1.8.1.2

Re: [PATCH] can: flexcan: Deferred on Regulator return EPROBE_DEFER

[Marc Kleine-Budde]

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On 03/22/2015 05:35 PM, Andreas Werner wrote:
> Return EPROBE_DEFER if Regulator returns EPROBE_DEFER
> 
> If the Flexcan driver is built into kernel and a regulator is used to
> enable the CAN transceiver, the Flexcan driver may not use the regulator.
> 
> When initializing the Flexcan device with a regulator defined in the device
> tree, but not initialized, the regulator subsystem returns EPROBE_DEFER, hence
> the Flexcan init fails.
> 
> The solution for this is to return EPROBE_DEFER if regulator is not initialized
> and wait until the regulator is initialized.
> 
> Signed-off-by: Andreas Werner <kernel@andy89.org>

Applied to can, with some minor changes.

> ---
> I tested this Patch on a self made Freescale Vybrid VF610 board we developed in
> the Formula Student Team of the UaS RheinMain. I think this Patch is working on
> all other SoC with a Flexcan Controller. I tested it with the head rev of
> linux-can and linux 3.19.2.
> 
> Since this is my first patch for the Linux Kernel, please tell me if
> there are formal
> failures.

No failures, but you can improve things. Please use git send-email to
post your patches, as your MUA, which is probably google, converts the
tabs into spaces, so that the patch doesn't apply anymore.

> ---
>  drivers/net/can/flexcan.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
> index b1d583b..c575163 100644
> --- a/drivers/net/can/flexcan.c
> +++ b/drivers/net/can/flexcan.c
> @@ -1164,11 +1164,19 @@ static int flexcan_probe(struct platform_device *pdev)
>      void __iomem *base;
>      int err, irq;
>      u32 clock_freq = 0;
> +    struct regulator *reg_xceiver = NULL;
> 
>      if (pdev->dev.of_node)
>          of_property_read_u32(pdev->dev.of_node,
>                          "clock-frequency", &clock_freq);
> 
> +    reg_xceiver = devm_regulator_get(&pdev->dev, "xceiver");
> +    if (PTR_ERR(reg_xceiver) == -EPROBE_DEFER) {
> +        return -EPROBE_DEFER;
> +    } else if (IS_ERR(reg_xceiver)) {
> +        reg_xceiver = NULL;
> +    }

I've moved this in front of the of_property_read_u32, as I don't want to
tear the clock handling apart. Further I've removed the curly braces.

> +
>      if (!clock_freq) {
>          clk_ipg = devm_clk_get(&pdev->dev, "ipg");
>          if (IS_ERR(clk_ipg)) {
> @@ -1225,10 +1233,7 @@ static int flexcan_probe(struct platform_device *pdev)
>      priv->clk_per = clk_per;
>      priv->pdata = dev_get_platdata(&pdev->dev);
>      priv->devtype_data = devtype_data;
> -
> -    priv->reg_xceiver = devm_regulator_get(&pdev->dev, "xceiver");
> -    if (IS_ERR(priv->reg_xceiver))
> -        priv->reg_xceiver = NULL;
> +    priv->reg_xceiver = reg_xceiver;
> 
>      netif_napi_add(dev, &priv->napi, flexcan_poll, FLEXCAN_NAPI_WEIGHT);
> 

Marc

-- 
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