On Mon, Mar 11, 2019 at 10:41:40AM +0000, Abel Vesa wrote: > On 19-03-11 11:28:25, Sascha Hauer wrote: > > Hi Abel, > > > > On Thu, Mar 07, 2019 at 09:20:37AM +0000, Abel Vesa wrote: > > > By default, the muxes should re-parent on set_rate. > > > This would allow the drivers to control only the leaf clock node, > > > leaving the rest to the clock driver, that way simplifying the > > > clock control. > > > > I am afraid of this change. Besides the rate there might be other > > reasons to choose one mux input over another, consider for example low > > power audio playback where we need one specific mux setting because it > > provides a clock which runs at low power mode. > > On the IPU on i.MX5/6 there are clocks being used as pixel clocks > > derived from different muxes. I don't think you want to pick an input > > clock just because it happens to deliver the best clock rate at that > > point in time, but really is shared with some other clock that changes > > its rate in the next moment. > > > > > I have no concrete examples for things that break with this change, but > > I would be more confident if we change the behaviour explicitly only for > > the muxes that we have reviewed to cope with this change. > > > > Fair enough. We could replace all the imx_clk_mux with imx_clk_mux_noreparent > and after that we can independently switch the clocks that are safe (to > switch) > to imx_clk_mux (which would not have the noreparent flag set).
Ok with me. > > The main idea is to simplify the clock control from drivers point of view. Which drivers do you have in mind? I hardly ever missed reparenting on rate changes, so where is this feature useful? Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
