Date: Sat, 30 May 2015 09:26:01 -0600 From: Ian Lepore <ian@freebsd.org> To: Pratik Singhal <ps06756@gmail.com> Cc: freebsd-hackers <freebsd-hackers@freebsd.org> Subject: Re: Difference b/w xfer_len and len fields Message-ID: <1432999561.1200.106.camel@freebsd.org> In-Reply-To: <CAGf2gkM1QNTpw5ROhPS-DXrohDc8v-D9jSfjUGPxLfaoG6v2Kg@mail.gmail.com> References: <CAGf2gkMuL0JDnX5PRvWKRSnmAHOFY4jzQEOjM6MQ8u9G4FuLbA@mail.gmail.com> <1432993550.1200.104.camel@freebsd.org> <CAGf2gkM1QNTpw5ROhPS-DXrohDc8v-D9jSfjUGPxLfaoG6v2Kg@mail.gmail.com>
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On Sat, 2015-05-30 at 20:17 +0530, Pratik Singhal wrote: > What do you mean by "driver-internal" variables ? > I mean that it is used within the lowest-level hardware-controller driver, and is not used in any communication between that lowest layer and the mmc or mmcsd layers. -- Ian > On Sat, May 30, 2015 at 7:15 PM, Ian Lepore <ian@freebsd.org> wrote: > > > On Sat, 2015-05-30 at 11:26 +0530, Pratik Singhal wrote: > > > What is the difference b/w the xfer_len and the len fields in the struct > > > mmc_data in file sys/dev/mmc/mmcreg.h ? > > > > > > AFAIK , len is the length of the data present in mmc_data , what is > > > xfer_len ? > > > > > > > The xfer_len field has historically been unused, until recently. When > > the dwc mmc driver was added, it uses xfer_len as a driver-internal > > variable to track how much of the overal work is done as the IO > > proceeds. > > > > -- Ian > > > > > >
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