Re: bus_get_dma_tag now necessary for drivers using bus_dma

Warner Losh wrote this message on Tue, Sep 05, 2006 at 13:02 -0600:
In message: <14026.1157478288@xxxxxxxxxxxxxxxxxx>
"Poul-Henning Kamp" <phk@xxxxxxxxxxxxxx> writes:
: In message <20060905173334.GH9421@xxxxxxxxxxxx>, John-Mark Gurney writes:
:
: >This means that for each call to bus_dma_tag_create, instead of passing
: >a NULL pointer, you should call bus_get_dma_tag(yourdev) and use that
: >as the parent tag. I committed some example code to various drivers,
: >such as ahc, ata, em, and ohci.
:
: If there are never any exeptions to this requirement, why not
: pass "yourdev" and have the magic hidden, rather than add 17
: ritual characters to the API ?

As Scott pointed out, it won't always be NULL. I like his idea of
having a variant that takes a device_t...

I thought of something similar. I like the idea of not having to call
bus_get_dma_tag every time, but at the same time, I didn't like adding
yet another function that does almost the same thing... If more
arguments were effected, I'd be less inclined to argue, but all we'd
be doing would change:
bus_dma_tag_create(bus_get_dma_tag(dev),
to:
bus_dma_tag_dev_create(dev,

Which though less typing, does create another entry point for creating
a bus_dma_tag_t....

I'm split on which is the better way, so if someone wants to change it
to the second, I have no objections....

--
John-Mark Gurney Voice: +1 415 225 5579

"All that I will do, has been done, All that I have, has not."
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