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 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?
By the looks of it, the driver is interrupting per character (ie per byte). If you copy half your output above into a text editor, and count the characters, including one byte per line end, you get 605. I can't speak for the driver implementation, but it sounds fair enough to me. Cheers, -- Matt -- To unsubscribe from this list: send the line "unsubscribe linux-m68k" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
