Re: Dual SJA1000 can controllers on SMP system.

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

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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.

Med Vänliga Hälsningar / Best Regards
Mirza

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Mirza Krak
Host Mobility AB
mirza.krak@hostmobility.com
Anders Personsgatan 12, 416 64 Göteborg
Sweden
www.hostmobility.com <http://www.hostmobility.com>
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On 06/17/2013 09:18 AM, Marc Kleine-Budde wrote:
> On 06/17/2013 08:10 AM, Mirza Krak wrote:
>> Aah off course. The low-level device driver is sja1000_platform.c. The
>> functions I am using are sp_read_reg8 and sp_write_reg8 which I have
>> slightly modified. Since I don't use multiplexed bus functionality I
>> write the address first.
>>
>>    static u8 sp_read_reg8(const struct sja1000_priv *priv, int reg)
>> {
>>      iowrite8(reg, priv->reg_base);
>        ^^^^^^^^
>>      return ioread8(priv->reg_base + 0x20);
>> }
>>
>> static void sp_write_reg8(const struct sja1000_priv *priv, int reg, u8 val)
>> {
>>      iowrite8(reg, priv->reg_base);
>        ^^^^^^^^
>>      iowrite8(val, (priv->reg_base + 0x20));
>> }
>
> Can you post a proper patch, so that we can see what you have changed?
>
> You probably have a nice race condition here. The two iowrites have to
> be atomic.
>
> Marc
>

[-- Attachment #2: sja1000_platform.patch --]
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Index: sja1000_platform.c
===================================================================
--- sja1000_platform.c	(revision 160)
+++ sja1000_platform.c	(working copy)
@@ -38,12 +38,14 @@
 
 static u8 sp_read_reg8(const struct sja1000_priv *priv, int reg)
 {
-	return ioread8(priv->reg_base + reg);
+	iowrite8(reg, priv->reg_base);
+	return ioread8(priv->reg_base + 0x20);
 }
 
 static void sp_write_reg8(const struct sja1000_priv *priv, int reg, u8 val)
 {
-	iowrite8(val, priv->reg_base + reg);
+	iowrite8(reg, priv->reg_base);
+	iowrite8(val, (priv->reg_base + 0x20));
 }
 
 static u8 sp_read_reg16(const struct sja1000_priv *priv, int reg)