uart issues on coldfire platform

[Lanttor <lanttor.guo@freescale.com>]

> Hi,
>
> I find one issue of UART on my coldfire platforms (mcf54451evb board).
> I use the linux-2.6.29, and use drivers/serial/mcf.c and
> drivers/serial/serial_core.c as my uart driver source.
>
> Following is my test steps -- run command: cat /proc/interrupts two
> times contiguously.
>
> [root@freescale /]# cat /proc/interrupts
> M5445X    *90:       5099 UART*
> M5445X    96:       3130 timer0
> M5445X    99:          0 timer3
> M5445X   100:       1569 fec(TXF)
> M5445X   101:          0 fec(TXB)
> M5445X   102:          0 fec(TXFIFO)
> M5445X   103:          0 fec(TXCR)
> M5445X   104:       3098 fec(RXF)
> M5445X   105:          0 fec(RXB)
> M5445X   106:         41 fec(MII)
> M5445X   107:          0 fec(LC)
> M5445X   108:          0 fec(HBERR)
> M5445X   109:          0 fec(GRA)
> M5445X   110:          0 fec(EBERR)
> M5445X   111:          0 fec(BABT)
> M5445X   112:          0 fec(BABR)
> [root@freescale /]# cat /proc/interrupts
> M5445X    *90:       5714 UART*
> M5445X    96:       3700 timer0
> M5445X    99:          1 timer3
> M5445X   100:       1574 fec(TXF)
> M5445X   101:          0 fec(TXB)
> M5445X   102:          0 fec(TXFIFO)
> M5445X   103:          0 fec(TXCR)
> M5445X   104:       3108 fec(RXF)
> M5445X   105:          0 fec(RXB)
> M5445X   106:         47 fec(MII)
> M5445X   107:          0 fec(LC)
> M5445X   108:          0 fec(HBERR)
> M5445X   109:          0 fec(GRA)
> M5445X   110:          0 fec(EBERR)
> M5445X   111:          0 fec(BABT)
> M5445X   112:          0 fec(BABR)
>
> I find that the interrupts for above operation is 5714 - 5099 = 605
> Is it normal? (my opinion it's too much)
>
> I test it on the mcf5329 board, it has the same-like result (even more 605).
> Actually I don't modify any code of mcf.c and serial_core.c, but I don't
> know why so much interrupts are occurred through one operation?
>
> Regards,
> Lanttor
>
>
>
>