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Date:      Tue, 05 Sep 2006 13:02:47 -0600 (MDT)
From:      "M. Warner Losh" <imp@bsdimp.com>
To:        phk@phk.freebsd.dk
Cc:        gurney_j@resnet.uoregon.edu, freebsd-current@freebsd.org, freebsd-drivers@freebsd.org, freebsd-arch@freebsd.org
Subject:   Re: bus_get_dma_tag now necessary for drivers using bus_dma 
Message-ID:  <20060905.130247.-267228160.imp@bsdimp.com>
In-Reply-To: <14026.1157478288@critter.freebsd.dk>
References:  <20060905173334.GH9421@funkthat.com> <14026.1157478288@critter.freebsd.dk>

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In message: <14026.1157478288@critter.freebsd.dk>
            "Poul-Henning Kamp" <phk@phk.freebsd.dk> writes:
: In message <20060905173334.GH9421@funkthat.com>, 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...

Warner



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