On Thu, Dec 9, 2010 at 11:38 PM, David Brownell <davi...@pacbell.net> wrote: > You know, the spi-gpio code was written so it > would not need Kconfiguration, and I'd like > to see that continued. > > Surely the minimal configuration you'd need > could be wrapped up in #defineslike the > actual GPIO numbers are wrapped up in. > > Heck, nothing outside your patches needs your > :slow it way the heck down" option, so there's > no point to exposing it via Kconfig; > such stuff is routinely embedded in C code.
Hi David, Thanks for your comments. I'm glad to get a better picture of what you expect from future proposed changes to spi_gpio. Ok. Kconfig is clearly not an acceptable way to keep spi_gpio fast for those who want it. > Would it make more sense to have a separate > slowed-down veresion of the driver, maybe just > custom defs for our hardware plus the current > driver body, as explained in the driver code > (last time I looked at it, anyway). I'm hearing that a separate driver is. > (I notice you didn't even check the GPIOs to see > if they are sleeping calls (e.g. over I2C), which > would have been preferable to a static always-slow > Kconfig option. (But not to an always-slow object > vs the current default always-fast model. I hadn't thought that we could check for sleeping calls, thanks for that suggestion. > I still need to be able to get multi-megabit > SPI clock rates out of the standard spi-gpio > code base. (When I've had to use spi-gpio it > has never been a performance issue; the code > was written to facilitate inner bitbang loops > of about half a dozen instructions (ARM). Ok so current users of spi_gpio require it to operate 'as fast as it can.' But compile-time switching in the driver is undesireable. What I'm taking away from the discussion is that we should introduce a second bitbanging SPI master driver that reuses as much code as possible from the existing spi_gpio driver. Best Regards, Ben Gardiner --- Nanometrics Inc. http://www.nanometrics.ca ------------------------------------------------------------------------------ Lotusphere 2011 Register now for Lotusphere 2011 and learn how to connect the dots, take your collaborative environment to the next level, and enter the era of Social Business. http://p.sf.net/sfu/lotusphere-d2d _______________________________________________ spi-devel-general mailing list spi-devel-general@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/spi-devel-general
