On Wed, Nov 14, 2018 at 01:47:52PM +0100, Thierry Reding wrote: > On Tue, Nov 13, 2018 at 10:08:22AM +0800, Ryder Lee wrote: > > The flag 'has_clks' and related checks are superfluous as the CCF > > subsystem does this for you. > > Both of these mechanisms aren't equivalent. While CCF can deal with > optional clocks, what the has_clks flag actually means is that the > device doesn't need a clock (or doesn't have a clock input) on the > devices where it is cleared. > > So I'd actually be in favor of keeping the has_clks property because it > serves as an additional sanity check. For example if you run this driver > on an SoC that "has clocks" but if you don't list them in DT, then after > this patch the driver will happily continue without clocks, even though > it may break completely without those clocks. I've seen SoCs respond to > disabled clocks for a hardware block in different ways, in many cases an > access to any of the registers will completely hang the CPU. In other > cases it may just crash in some other way or give you some sort of > machine exception. None of those are good, and make the tiny bit of > additional code required to support the has_clks flag very attractive. > > But that's just my opinion. If you prefer to throw away that safety > barrier, be my guest. But if you do, please move this functionality into > the clock framework first and then make the driver use it. The usual policy is: If the things specified in the dt are wrong or incomplete, it's ok to fail however you like. So from a correctness POV I think the change is fine. I don't know about the mips details that John pointed out in a followup to this mail though. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |
