Messages in this thread | | | Date | Thu, 17 Jul 2008 14:52:52 -0700 | From | Randy Dunlap <> | Subject | Re: [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/
| |