Date: Tue, 5 Sep 2006 12:27:55 -0700 From: John-Mark Gurney <gurney_j@resnet.uoregon.edu> To: "M. Warner Losh" <imp@bsdimp.com> Cc: phk@phk.freebsd.dk, 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: <20060905192755.GI9421@funkthat.com> In-Reply-To: <20060905.130247.-267228160.imp@bsdimp.com> References: <20060905173334.GH9421@funkthat.com> <14026.1157478288@critter.freebsd.dk> <20060905.130247.-267228160.imp@bsdimp.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Warner Losh wrote this message on Tue, Sep 05, 2006 at 13:02 -0600:
> 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...
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."
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20060905192755.GI9421>