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* [PATCH] powerpc: enable a 30-bit ZONE_DMA for 32-bit pmac
@ 2019-06-13  8:24 Christoph Hellwig
  2019-06-13 18:51 ` Larry Finger
                   ` (4 more replies)
  0 siblings, 5 replies; 12+ messages in thread
From: Christoph Hellwig @ 2019-06-13  8:24 UTC (permalink / raw)
  To: benh, paulus, mpe; +Cc: Larry.Finger, linuxppc-dev, linux-kernel, aaro.koskinen

With the strict dma mask checking introduced with the switch to
the generic DMA direct code common wifi chips on 32-bit powerbooks
stopped working.  Add a 30-bit ZONE_DMA to the 32-bit pmac builds
to allow them to reliably allocate dma coherent memory.

Fixes: 65a21b71f948 ("powerpc/dma: remove dma_nommu_dma_supported")
Reported-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/powerpc/include/asm/page.h         | 7 +++++++
 arch/powerpc/mm/mem.c                   | 3 ++-
 arch/powerpc/platforms/powermac/Kconfig | 1 +
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index b8286a2013b4..0d52f57fca04 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -319,6 +319,13 @@ struct vm_area_struct;
 #endif /* __ASSEMBLY__ */
 #include <asm/slice.h>
 
+/*
+ * Allow 30-bit DMA for very limited Broadcom wifi chips on many powerbooks.
+ */
+#ifdef CONFIG_PPC32
+#define ARCH_ZONE_DMA_BITS 30
+#else
 #define ARCH_ZONE_DMA_BITS 31
+#endif
 
 #endif /* _ASM_POWERPC_PAGE_H */
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index cba29131bccc..2540d3b2588c 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -248,7 +248,8 @@ void __init paging_init(void)
 	       (long int)((top_of_ram - total_ram) >> 20));
 
 #ifdef CONFIG_ZONE_DMA
-	max_zone_pfns[ZONE_DMA]	= min(max_low_pfn, 0x7fffffffUL >> PAGE_SHIFT);
+	max_zone_pfns[ZONE_DMA]	= min(max_low_pfn,
+			((1UL << ARCH_ZONE_DMA_BITS) - 1) >> PAGE_SHIFT);
 #endif
 	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
 #ifdef CONFIG_HIGHMEM
diff --git a/arch/powerpc/platforms/powermac/Kconfig b/arch/powerpc/platforms/powermac/Kconfig
index f834a19ed772..c02d8c503b29 100644
--- a/arch/powerpc/platforms/powermac/Kconfig
+++ b/arch/powerpc/platforms/powermac/Kconfig
@@ -7,6 +7,7 @@ config PPC_PMAC
 	select PPC_INDIRECT_PCI if PPC32
 	select PPC_MPC106 if PPC32
 	select PPC_NATIVE
+	select ZONE_DMA if PPC32
 	default y
 
 config PPC_PMAC64
-- 
2.20.1


^ permalink raw reply	[flat|nested] 12+ messages in thread

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Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-06-13  8:24 [PATCH] powerpc: enable a 30-bit ZONE_DMA for 32-bit pmac Christoph Hellwig
2019-06-13 18:51 ` Larry Finger
2019-06-14  7:24 ` Mathieu Malaterre
2019-06-14 19:15   ` Aaro Koskinen
2019-06-14 20:26     ` Larry Finger
2019-06-14 19:02 ` Aaro Koskinen
2019-06-19 10:50 ` Christoph Hellwig
2019-06-19 12:32   ` Michael Ellerman
2019-06-19 13:31     ` Benjamin Herrenschmidt
2019-06-19 14:28       ` Mathieu Malaterre
2019-06-20 13:49       ` Michael Ellerman
2019-06-23 10:34 ` Michael Ellerman

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