Thanks Greg/Matt/Cris' reply. I know it's not the issue now :)
Most of the ColdFire UART blocks have no transmit FIFO, so you
are going to get 1 interrupt per character. The above block has
at least 500 characters in it (including white space). Then include
the extra command prompt and you typing (receive interrupts) and I
would figure that is going to come to around 600 interrupts.
So, yes, that seems about right.
Check the actual character count using:
cat /proc/tty/driver/mcf
Indeed it is. The UART transmit Buffer in my board is 1 character size
(no FIFO), only receiver has FIFO.
I test command "cat /proc/tty/driver/mcf", the result is as follows:
[root@freescale /]# cat /proc/tty/driver/mcf
serinfo:1.0 driver revision:
0: uart:ColdFire UART mmio:0xFC060000 irq:90 tx:54821 rx:91 RTS|DTR|CD
[root@freescale /]# cat /proc/interrupts
M5445X 90: 55042 UART
M5445X 96: 9962 timer
M5445X 99: 2 timer
M5445X 100: 3761 fec(TXF)
M5445X 101: 0 fec(TXB)
M5445X 102: 0 fec(TXFIFO)
M5445X 103: 0 fec(TXCR)
M5445X 104: 8169 fec(RXF)
M5445X 105: 0 fec(RXB)
M5445X 106: 110 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/tty/driver/mcf
serinfo:1.0 driver revision:
0: uart:ColdFire UART mmio:0xFC060000 irq:90 tx:55603 rx:115 RTS|DTR|CD
Thanks!
Regards,
Lanttor
------------------------------------------------------------------------
*From:* Greg Ungerer <gerg@xxxxxxxxxxxx>
*Sent:* 07/02/2009 8:40:49 AM +0800
*To:* uClinux development list <uclinux-dev@xxxxxxxxxxx>
*CC:* linux-m68k@xxxxxxxxxxxxxxx
*Subject:* [uClinux-dev] uart issues on coldfire platform
Hi Lanttor,
Lanttor wrote:
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
^^^^^^^^^^^^^ 615 ?
Is it normal? (my opinion it's too much)
Most of the ColdFire UART blocks have no transmit FIFO, so you
are going to get 1 interrupt per character. The above block has
at least 500 characters in it (including white space). Then include
the extra command prompt and you typing (receive interrupts) and I
would figure that is going to come to around 600 interrupts.
So, yes, that seems about right.
Check the actual character count using:
cat /proc/tty/driver/mcf
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?
That is the price you pay with no data FIFO's in these UART cores.
(Some of the ColdFire parts support DMA with the UART - the mcf
driver doesn't currently use this though).
Regards
Greg
------------------------------------------------------------------------
Greg Ungerer -- Principal Engineer EMAIL: gerg@xxxxxxxxxxxx
SnapGear Group, McAfee PHONE: +61 7 3435 2888
825 Stanley St, FAX: +61 7 3891 3630
Woolloongabba, QLD, 4102, Australia WEB: http://www.SnapGear.com
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