linux-kernel - [PATCH 09/10] sh: don't allow non-coherent DMA for NOMMU

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Message-Id: <20200324162633.754714-10-hch@lst.de>
Date:   Tue, 24 Mar 2020 17:26:32 +0100
From:   Christoph Hellwig <hch@....de>
To:     Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>
Cc:     linux-sh@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 09/10] sh: don't allow non-coherent DMA for NOMMU

The code handling non-coherent DMA depends on being able to remap code
as non-cached.  But that can't be done without an MMU, so using this
option on NOMMU builds is broken.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 arch/sh/Kconfig | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 808b638b11f3..b97d9712c252 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -48,6 +48,7 @@ config SUPERH
 	select MAY_HAVE_SPARSE_IRQ
 	select MODULES_USE_ELF_RELA
 	select NEED_SG_DMA_LENGTH
+	select NO_DMA if !MMU && !DMA_COHERENT
 	select NO_GENERIC_PCI_IOPORT_MAP if PCI
 	select OLD_SIGACTION
 	select OLD_SIGSUSPEND
@@ -155,7 +156,7 @@ config DMA_COHERENT
 	bool
 
 config DMA_NONCOHERENT
-	def_bool !DMA_COHERENT
+	def_bool !NO_DMA && !DMA_COHERENT
 	select ARCH_HAS_SYNC_DMA_FOR_DEVICE
 
 config PGTABLE_LEVELS
-- 
2.25.1