Messages in this thread | | | Date | Fri, 10 Dec 2010 11:37:06 +0100 | From | Nicolas Ferre <> | Subject | Re: [RFC PATCH] scatterlist: Initialize the dma_address field with invalid dma address |
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Le 09/12/2010 21:00, David Miller : > From: Nicolas Ferre <nicolas.ferre@atmel.com> > Date: Thu, 9 Dec 2010 14:15:14 +0100 > >> Initialize the the dma_address field so that it will be possible to test >> its value while using scatterlists. This field will be compatible with >> testing by dma_mapping_error(). >> >> Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com> > > Please don't do this, it's unjustified and it's going to kill performance.
Yes, that is what I suspected...
> Even if it were a good change, you should have used the invalid DMA > address definition defined by various architectures instead of a constant.
Well this definition seems to be spread among drivers (mostly usb ones): DMA_ADDR_INVALID... And also sometimes with different names: DMA_INVALID_HANDLE, INVALID_DMA_ADDRESS
> You should be aware of whether entries in a scatterlist have been setup > by your code path.
Yes, in fact my need is related to the fact that my scatterlist is filled in a driver and then handled by the dmaengine driver. But I will reconsider the path taken by my sg to be able to avoid checking the dma_address field.
Best regards, -- Nicolas Ferre
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