On Wed, 10 Jun 2009, Hans Verkuil wrote: > On Wednesday 10 June 2009 23:30:55 Guennadi Liakhovetski wrote: > > On Wed, 10 Jun 2009, Hans Verkuil wrote: > > > My view of this would be that the board specification specifies the > > > sensor (and possibly other chips) that are on the board. And to me it > > > makes sense that that also supplies the bus settings. I agree that it > > > is not complex code, but I think it is also unnecessary code. Why > > > negotiate if you can just set it? > > > > Why force all platforms to set it if the driver is perfectly capable do > > this itself? As I said - this is not a platform-specific feature, it's > > chip-specific. What good would it make to have all platforms using > > mt9t031 to specify, that yes, the chip can use both falling and rising > > pclk edge, but only active high vsync and hsync? > > ??? > > You will just tell the chip what to use. So you set 'use falling edge' and > either set 'active high vsync/hsync' or just leave that out since you know > the mt9t031 has that fixed. You don't specify in the platform data what the > chip can support, that's not relevant. You know what the host expects and > you pass that information on to the chip. > > A board designer knows what the host supports, No, he doesn't have to. That's not board specific, that's SoC specific. > knows what the sensor supports, Ditto, this is sensor-specific, not board-specific. > and knows if he added any inverters on the board, and based on > all that information he can just setup these parameters for the sensor > chip. Settings that are fixed on the sensor chip he can just ignore, he > only need to specify those settings that the sensor really needs. Of all the boards that I know of that use soc-camera only one (supposedly) had an inverter on one line, and even that one is not in the mainline. So, in the present soc-camera code not a single board have to bother with that. And now you want to add _all_ those polarity, master / slave flags to _all_ of them? Let me try again: you have an HSYNC output on the sensor. Its capabilities are known to the sensor driver you have an HSYNC input on the SoC. Its capabilities are known to the SoC-specific camera host driver these two lines are routed on the board to connect either directly or over some logic, hopefully, not more complex than an inverter. Now, this is _the_ _only_ bit of information, that is specific to the board. Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
