Hi Mauro, On Monday 15 April 2013 09:42:48 Mauro Carvalho Chehab wrote: > Em Mon, 15 Apr 2013 12:19:23 +0200 Laurent Pinchart escreveu: > > On Sunday 14 April 2013 16:59:58 Mauro Carvalho Chehab wrote: > > > Em Fri, 12 Apr 2013 11:13:06 +0200 Laurent Pinchart escreveu: > > > > Hi Mauro, > > > > > > > > The following changes since commit > > > > 81e096c8ac6a064854c2157e0bf802dc4906678c: > > > > [media] budget: Add support for Philips Semi Sylt PCI ref. design > > > > > > > > (2013-04-08 07:28:01 -0300) > > > > > > > > are available in the git repository at: > > > > git://linuxtv.org/pinchartl/media.git sensors/next > > > > > > > > for you to fetch changes up to c890926a06339944790c5c265e21e8547aa55e49: > > > > mt9p031: Use the common clock framework (2013-04-12 11:07:07 +0200) > > > > > > > > ---------------------------------------------------------------- > > > > > > > > Laurent Pinchart (5): > > > > mt9m032: Fix PLL setup > > > > mt9m032: Define MT9M032_READ_MODE1 bits > > > > mt9p031: Use devm_* managed helpers > > > > mt9p031: Add support for regulators > > > > mt9p031: Use the common clock framework > > > > > > Hmm... It seems ugly to have regulators and clock framework and other > > > SoC calls inside an i2c driver that can be used by a device that doesn't > > > have regulators. > > > > > > I'm not sure what's the best solution for it, so, I'll be adding those > > > two patches, but it seems that we'll need to restrict the usage of those > > > calls only if the caller driver is a platform driver. > > > > The MT9P031 needs power supplies and a clock on all platforms, regardless > > of the bridge bus type. > > Well, all digital devices require clock and power. If power is either a > simple electric circuit, a battery or a regulator, that depends on the > board. > > > I suppose the use case that mostly concerns you here is > > USB webcams > > Yes. > > > where the power supplies and the clock are controlled automatically by the > > device. > > Or could be not controlled at all. It could be a simple XTAL attached to the > sensor or a clock signal provided by the bridge obtained from a fixed XTAL, > and a resistor bridge or a Zenner diode providing the needed power voltage. > > > If we ever need to support such a device in the future we can of course > > revisit the driver then, and one possible solution would be to register > > fixed voltage regulators and a fixed clock. > > That is an overkill: devices were the power supply/xtal clock can't be > controlled should not require extra software that pretend to control it. If I'm not mistaken that's however the recommended way on embedded devices at the moment. I don't have a strong opinion on the subject for now, but this will need to be at least discussed with core clock and regulator developers. -- Regards, Laurent Pinchart -- 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
