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    SubjectRe: [PATCH 29/30] W1: Documentation/w1/masters/ds2490 update
    On Mon, 14 Jul 2008 21:16:56 -0500 David Fries wrote:

    > On Mon, Jul 14, 2008 at 01:40:02PM -0700, Randy Dunlap wrote:
    > > > +- The number of USB bus transactions could be reduced if w1_reset_send
    > > > + was added to the API. The name is just a suggestion. It would take
    > > > + a write buffer and a read buffer (along with sizes) as arguments.
    > > > + It would add match rom and rom to the send buffer, reset the bus,
    > > ~~~~~~~~~~~~~~~~~
    > > Can you clarify above?
    >
    > I re-wrote the paragraph. In the one wire protocol a bus reset is
    > followed by a one byte command, in this case match rom which tells all
    > the devices on the bus to expect an 8byte rom (slave device id) and
    > only the slave device that matches the rom is to respond to the
    > following message. I was assuming people reading it would be familiar
    > with the one wire bus protocol. Do you have any of the one wire
    > hardware?

    No. :(

    > - The number of USB bus transactions could be reduced if w1_reset_send
    > was added to the API. The name is just a suggestion. It would take
    > a write buffer and a read buffer (along with sizes) as arguments.
    > The ds2490 block I/O command supports reset, write buffer, read
    > buffer, and strong pullup all in one command, instead of the current
    > 1 reset bus, 2 write the match rom command and slave rom id, 3 block
    > write and read data. The write buffer needs to have the match rom
    > command and slave rom id prepended to the front of the requested
    > write buffer, both of which are known to the driver.
    >
    > The next paragraph was removed, I decided that listing the commands
    > giong from three to one was enough, I didn't need to count all the USB
    > bus transactions.
    >
    > I'll send the patch again in the next e-mail.

    Thanks.

    ---
    ~Randy
    Linux Plumbers Conference, 17-19 September 2008, Portland, Oregon USA
    http://linuxplumbersconf.org/


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