Re: [MiNT] [PATCH] EHCI driver interrupt checking.

[Hrafnkell Hlodversson <keli@keli.dk>]

Hi me again. (Nice conversation I’m having with myself here.)

I realized that I misread the original comment, since d0 is the return value, it should only be restored when our handler does not use it. I see that the _ehci_interrupt_handle will preserve the value of d0 when needed by returning the original value, and the original code was correct.

Just forget the whole thing happened ;)

// Keli


> On 10 Dec 2014, at 11:23, Hrafnkell Hlodversson <keli@keli.dk> wrote:
> 
> Whoops! I just learned that the Coldfire can’t update the stack pointer in the movem instruction, so it would be (although *still* not tested):
>> _ehci_int_handle_asm:
>> 	subq.l #12, sp
>> 	movem.l d0-d1/a1,(sp) // save d0, d1 and a1 to stack
>> 	move.l a0,-(sp)		// PCI_BIOS specification: parameter is in a0
>> 	jsr _ehci_interrupt_handle
>> 	addq.l #4,sp // Clean up argument from stack as per C calling conventions
>> 	movem.l (sp),d0-d1/a1 // restore old values of d0, d1 and a1
>> 	addq.l #12, sp
>> 	rts
> 
>> On 10 Dec 2014, at 11:16, Hrafnkell Hlodversson <keli@keli.dk> wrote:
>> 
>> Hello everyone, I’ve been lurking this list (and watching the CVS commits for a while)
>> 
>> I did a quick read through this diff, and it seems there is a problem with how you’re saving d0.
>>> + move.l d0,-(sp) 
>> The above does save it to the stack, but after returning from ehci_interrupt_handle:
>>> -	addq.l #4,sp
>>> +	addq.l #8,sp
>> you simply add 4 more bytes to the stack pointer instead of restoring it.
>> Also there is a movem.l instruction already there, maybe you should just add the d0 to the lists of registers to be pushed to that one?
>> 
>> Something like this (First 68k assembly I’ve written in this century and completely untested, so don’t shoot me ;P )
>>> 
>>> _ehci_int_handle_asm:
>>> 	movem.l d0-d1/a1,-(sp) // save d0, d1 and a1 to stack
>>> 	move.l a0,-(sp)		// PCI_BIOS specification: parameter is in a0
>>> 	jsr _ehci_interrupt_handle
>>> 	addq.l #4,sp // Clean up argument from stack as per C calling conventions
>>> 	movem.l (sp)+,d0-d1/a1 // restore old values of d0, d1 and a1
>>> 	rts
>> 
>> 
>> With kind regards
>> Keli
>> 
>>> On 02 Dec 2014, at 10:11, David Gálvez <dgalvez75@gmail.com> wrote:
>>> 
>>> PCI interrupt handlers are put into chain.
>>> Check if the interrupt was triggered by the device we're driving.
>>> Return d0 register unmodified if the interrupt is not ours.
>>> Contributed by David Galvez.
>>> <ehci_check_interrupt_20141202.diff>
>> 
>