Re: Dual SJA1000 can controllers on SMP system.

[Mirza Krak <mirza.krak@hostmobility.com>]

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Thank you Marc for your patch. We  applied it but it did not solve our 
problem.

Wolfgang suggested defining a lock common for all devices:

  static DEFINE_SPINLOCK(snor_bus_lock);

Which I applied and now it seems to work perfectly. Thank you for your help.

Should I blame the hardware driver? :)

Attaching the patch for reference .

Med Vänliga Hälsningar / Best Regards
Mirza

*******************************************************************
Mirza Krak
Host Mobility AB
mirza.krak@hostmobility.com
Anders Personsgatan 12, 416 64 Göteborg
Sweden
www.hostmobility.com <http://www.hostmobility.com>
Direct: +46 31 31 32 704
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On 06/17/2013 04:12 PM, Marc Kleine-Budde wrote:
> On 06/17/2013 03:46 PM, Mirza Krak wrote:
>> My modifications to sja1000_platform.c are attached as a patch.
>>
>> Wolfgang: Using spinlock_irqsave() and spinlock_irqrestore() was also my
>> initial idea on the io functions but I tried this without it solving the
>> problem. I could try this again to be sure.
>
> Without problem locking it not work anyway. Try the attached patch (it's
> compile time tested only).
>
> Marc
>

[-- Attachment #2: sja1000_platform.c.patch --]
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Index: drivers/net/can/sja1000/sja1000_platform.c
===================================================================
--- drivers/net/can/sja1000/sja1000_platform.c	(revision 519)
+++ drivers/net/can/sja1000/sja1000_platform.c	(working copy)
@@ -27,6 +27,7 @@
 #include <linux/can/dev.h>
 #include <linux/can/platform/sja1000.h>
 #include <linux/io.h>
+#include <linux/spinlock_types.h>
 
 #include "sja1000.h"
 
@@ -36,16 +37,29 @@
 MODULE_DESCRIPTION("Socket-CAN driver for SJA1000 on the platform bus");
 MODULE_LICENSE("GPL v2");
 
+static DEFINE_SPINLOCK(snor_bus_lock);
+
 static u8 sp_read_reg8(const struct sja1000_priv *priv, int reg)
 {
+	u8 value;
+	unsigned long flags;
+
+	spin_lock_irqsave(&snor_bus_lock, flags);
 	iowrite8(reg, priv->reg_base);
-	return ioread8(priv->reg_base + 0x20);
+	value = ioread8(priv->reg_base + 0x20);
+	spin_unlock_irqrestore(&snor_bus_lock, flags);
+
+	return value;
 }
 
 static void sp_write_reg8(const struct sja1000_priv *priv, int reg, u8 val)
 {
+	unsigned long flags;
+
+	spin_lock_irqsave(&snor_bus_lock, flags);
 	iowrite8(reg, priv->reg_base);
 	iowrite8(val, (priv->reg_base + 0x20));
+	spin_unlock_irqrestore(&snor_bus_lock, flags);
 }
 
 static u8 sp_read_reg16(const struct sja1000_priv *priv, int reg)