Linux (GPIO) Interrupt speed problems

Hello,

I am using a DM3730 and have setup the use of a GPIO pin 170 as a source for a linux kernel interrupt specifically to interface to the INT signal from an MCP2515 can controller.  The kernel config is like this:

static struct spi_board_info omap3tao3530_spi_can_board_info[] = {
 {
 .modalias = "mcp251x",
 .platform_data = &spi3_mcp2515_pdata,
 .irq = OMAP_GPIO_IRQ(OVERO_GPIO_CAN_INT),
 .max_speed_hz = 8*1000*1000,
 .bus_num = 3,
 .mode = SPI_MODE_0,
 .chip_select = 0,
 },

};

and the pin setup

static void __init spi3_mcp251x_init(void)
{
 printk(KERN_DEBUG "spi3_mcp251x_init: Entry\n");
 if ((gpio_request(OVERO_GPIO_CAN_INT, "MCP251x CAN INT") == 0) &&
 (gpio_direction_input(OVERO_GPIO_CAN_INT) == 0)) {
 gpio_export(OVERO_GPIO_CAN_INT, 0);
 set_irq_type(OMAP_GPIO_IRQ(OVERO_GPIO_CAN_INT), IRQ_TYPE_EDGE_FALLING);
 } else {
 printk(KERN_ERR "could not obtain gpio for MCP251x CAN bus interrupt\n");
 return;
 }
 gpio_direction_input(OVERO_GPIO_CAN_INT);

}  OMAP3_MUX(HDQ_SIO, OMAP_MUX_MODE4 | OMAP_PIN_INPUT), //GPIO interrupt

All seems to be working I can use the application that I have to send and receive data using the spi3 bus and the interrupt is seen.  The problem I am having however is that I cant seem to get a reliable interrupt seen by the kernel at anything faster than 10ms.  Is there any way that I can speed this reaction/scan time up ?

I have measured the time that it takes to see the interrupt, react and read all the data at ~380us so there is plenty of time for the exit of the irc function and to see the change in pin state.

I have had a look at the HZ definition and changed it from 100 to 1000 in an attempt to push the jiffies down to 1ms but this seems to have made things worse.  I just need reliable operation at relatively high interrupt rates and I would have thought that a ucontroller working at 800MHz should be capable of seeing and servicing a 1ms interrupt.

Is there anyone out there that understands my problem or maybe something I can change in the kernel config or code ?

Help greatfully appreciated and it means that my system is almost ready for V1 spin if I can prove that this interface works.

Thanks in advance

Marc