Thread (32 messages) 32 messages, 8 authors, 2015-05-21

Re: [V4 PATCH 3/6] pci: Generic function for setting up PCI device DMA coherency

From: Russell King - ARM Linux <hidden>
Date: 2015-05-20 20:47:14
Also in: linux-acpi, linux-arm-kernel, linux-crypto, lkml

On Wed, May 20, 2015 at 07:00:25AM -0500, Suravee Suthikulanit wrote:
On 5/20/2015 4:34 AM, Catalin Marinas wrote:
quoted
We have a dummy of_dma_configure() already when !CONFIG_OF, otherwise
we would need #ifndef here. I already replied, I think for other
architectures we need this check to avoid a useless host->of_node test.
It seems that there are several places that have similar check. Would it be
good to convert this into a macro? Something like:

#define OF_NODE_ENABLED(dev)	(IS_ENABLED(CONFIG_OF) && dev->of_node)
This /could/ be a useful compile-time optimisation: when CONFIG_OF is
disabled, dev->of_node exists but will always be NULL - but the
compiler doesn't know this.  Your suggestion above would tell the
compiler that when CONFIG_OF is disabled, OF_NODE_ENABLED() will
evaluate to a constant false, which means it can eliminate code.

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