This patch ensures that the TWIHS (i2c) hw get's its clock set when the sequence of

sam_i2cbus_initialize
sam_i2cbus_uninitialize
sam_i2cbus_initialize

Or twi_reset is called.

I found this a while back in the stm32 family, so there may be more arch-es with this sort of bug. I suppose any driver that has the notion of "do not set the freq if it is already set" could be suspect.

arch/arm/src/sam34/sam_twi.c

@@ -901,6 +901,7 @@ static void twi_hw_initialize(struct twi_dev_s *priv, unsigned int pid,
 
   /* Set the initial TWI data transfer frequency */
 
+  priv->i2cfreq = 0;
   twi_setfrequency(priv, frequency);
 }
 

arch/arm/src/sama5/sam_twi.c

@@ -1200,6 +1200,7 @@ static void twi_hw_initialize(struct twi_dev_s *priv, uint32_t frequency)
 
   /* Set the initial TWI data transfer frequency */
 
+  priv->frequency = 0
   twi_setfrequency(priv, frequency);
 
   /* Enable Interrupts */

arch/arm/src/samv7/sam_twihs.c

@@ -1230,6 +1230,7 @@ static void twi_hw_initialize(struct twi_dev_s *priv, uint32_t frequency)
 
   /* Set the initial TWIHS data transfer frequency */
 
+  priv->frequency  = 0;
   twi_setfrequency(priv, frequency);
 
   /* Enable Interrupts */