Re: Linux 6.4.4 on m68k - Q40 - pata_falcon causes oops at boot time

[William R Sowerbutts <will@sowerbutts.com>]

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On Sun, Aug 13, 2023 at 11:24:20PM +0100, William R Sowerbutts wrote:
>I am going to look at the pata_legacy driver and see if it might be usable 
>on the Q40 instead of pata_falcon.
>
>As a long term fix I think I need to read up on CONFIG_HAS_IOPORT_MAP to try 
>and understand how I might enable this.  I expect enabling it will have
>implications for all M68K machines, so maybe someone with more experience 
>should be making that decision.

Enabling CONFIG_HAS_IOPORT_MAP for the Q40 turned out to be simple.  Attached 
is the patch I am using -- it just sets NO_IOPORT_MAP=n when Q40 is enabled.

Enabling CONFIG_HAS_IOPORT_MAP allows pata_legacy to work on the Q40 with no 
further changes!

pata_legacy drives the IDE interface perfectly.  The data is byte swapped, so 
I think pata_falcon still has a place for Q40 users who want to use legacy 
reverse-byte-order disks.

I tested bulk transfer performance (exactly the same way as I tested 
pata_falcon with and without byte swapping); pata_legacy performs much the 
same as pata_falcon with byte swapping enabled (as one might expect).

I suppose the next step is to build a kernel supporting both Q40 and perhaps 
Atari, then test this in ARAnyM.  I'll try this out over the next few days.

Thanks

Will

_________________________________________________________________________
William R Sowerbutts                                  will@sowerbutts.com
"Carpe post meridiem"                               http://sowerbutts.com
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diff -urN linux-6.4.10.orig/arch/m68k/include/asm/kmap.h linux-6.4.10.q40/arch/m68k/include/asm/kmap.h
--- linux-6.4.10.orig/arch/m68k/include/asm/kmap.h	2023-08-11 11:14:29.000000000 +0100
+++ linux-6.4.10.q40/arch/m68k/include/asm/kmap.h	2023-08-16 00:34:12.894812394 +0100
@@ -58,6 +58,7 @@
 
 #endif /* CONFIG_MMU */
 
+#ifndef CONFIG_HAS_IOPORT_MAP
 #define ioport_map ioport_map
 static inline void __iomem *ioport_map(unsigned long port, unsigned int nr)
 {
@@ -68,5 +69,6 @@
 static inline void ioport_unmap(void __iomem *p)
 {
 }
+#endif /* CONFIG_HAS_IOPORT_MAP */
 
 #endif /* _KMAP_H */
diff -urN linux-6.4.10.orig/arch/m68k/Kconfig linux-6.4.10.q40/arch/m68k/Kconfig
--- linux-6.4.10.orig/arch/m68k/Kconfig	2023-08-11 11:14:29.000000000 +0100
+++ linux-6.4.10.q40/arch/m68k/Kconfig	2023-08-16 00:27:50.044269922 +0100
@@ -61,7 +61,8 @@
 	default y
 
 config NO_IOPORT_MAP
-	def_bool y
+        bool
+        default !Q40
 
 config HZ
 	int