Thread (7 messages) 7 messages, 4 authors, 2013-02-25

Re: [PATCH 01/11] ARM: disable virt_to_bus/virt_to_bus almost everywhere

From: James Hogan <hidden>
Date: 2013-02-20 15:14:51
Also in: linux-arm-kernel, lkml

On 14 February 2013 13:49, Arnd Bergmann [off-list ref] wrote:
quoted hunk
We are getting a number of warnings about the use of the deprecated
bus_to_virt function in drivers using the ARM ISA DMA API:

drivers/parport/parport_pc.c: In function 'parport_pc_fifo_write_block_dma':
drivers/parport/parport_pc.c:622:3: warning: 'bus_to_virt' is deprecated
(declared at arch/arm/include/asm/memory.h:253) [-Wdeprecated-declarations]

This is only because that function gets used by the inline
set_dma_addr() helper. We know that any driver for the ISA DMA API
is correctly using the DMA addresses, so we can change this
to use the __bus_to_virt() function instead, which does not warn.

After this, there are no remaining drivers that are used on
any defconfigs on ARM using virt_to_bus or bus_to_virt, with
the exception of the OSS sound driver. That driver is only used
on RiscPC, NetWinder and Shark, so we can set ARCH_NO_VIRT_TO_BUS
on all other platforms and hide the deprecated functions, which
is far more effective than marking them as deprecated, in order
to avoid any new users of that code.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <redacted>
---
 arch/arm/Kconfig                 | 4 ++++
 arch/arm/configs/shark_defconfig | 1 -
 arch/arm/include/asm/dma.h       | 2 +-
 arch/arm/include/asm/memory.h    | 2 ++
 4 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 67874b8..91d4aea 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1450,6 +1450,10 @@ config ISA_DMA
        bool
        select ISA_DMA_API

+config ARCH_NO_VIRT_TO_BUS
+       def_bool y
+       depends on !ARCH_RPC && !ARCH_NETWINDER && !ARCH_SHARK
Hi Arnd,

There's a patch in linux-next by Stephen Rothwell "Centralise
CONFIG_ARCH_NO_VIRT_TO_BUS" that removes this Kconfig symbol,
inverting/replacing it with "select HAVE_VIRT_TO_BUS" (including for
arch/arm) which will undo the effects of this.

Cheers
James
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