Question about memory resources

Question about memory resources

[H Hartley Sweeten]

Hello all,

I have written a backlight driver for the ep93xx.  The backlight
on this system is controlled by a pwm output with a single control
register.  This register is located in the memory resource used
by the ep93xx framebuffer.

The framebuffer uses the following resource:

static struct resource ep93xx_fb_resource[] = {
	{
		.start	= EP93XX_RASTER_PHYS_BASE,
		.end		= EP93XX_RASTER_PHYS_BASE + 0x800 - 1,
		.flags	= IORESOURCE_MEM,
	},
};

The backlight would use this resource:

static struct resource ep93xx_bl_resource[] = {
	{
		.start	= EP93XX_RASTER_PHYS_BASE + 0x20,
		.end		= EP93XX_RASTER_PHYS_BASE + 0x23,
		.flags	= IORESOURCE_MEM,
	},
};

Unfortunately this doesn't work because the request_mem_region
call fails when the second device is probed since the first
device already did a request_mem_region and it was marked as
IORESOURCE_BUSY.

Is there any way to handle this other than using the static i/o
mapping for the backlight register?

Regards,
Hartley

Question about memory resources

[Mark Brown]

On Thu, Mar 11, 2010 at 04:48:45PM -0600, H Hartley Sweeten wrote:

> Is there any way to handle this other than using the static i/o
> mapping for the backlight register?

The standard thing would be a MFD, or a single driver that exports both
interfaces.