Messages in this thread | | | Date | Thu, 27 Mar 2014 12:14:01 +0100 | From | Boris BREZILLON <> | Subject | Re: [PATCH] clk: register fixed-clock only if #clock-cells property is present |
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Hi Sylwester,
Le 27/03/2014 11:01, Sylwester Nawrocki a écrit : > Hi Boris, > > On 27/03/14 08:58, Boris BREZILLON wrote: >> This solution solve the problem for this specific case because clks are >> declared in the correct order in imx DTs. >> But, even with your patch I think we could see similar issues by >> reordering DT nodes... >> >> The real problem here is that imx platform does not declare the CCM clocks >> dependencies upon ckil, ckih1 and osc fixed clocks within the DT [1], and >> retrieve these clocks when initializing the CCM clocks ([2] and [3]). >> >> We should try to a add these dependencies in the DT and see if it works. > While presumably all of us agree the dependencies should be correctly > specified in dts I think we should minimize possible regressions by > keeping the clocks registration order as before, i.e. as parsed by the > kernel from DT. Rather than explicitly reversing it, which does not gain > us anything AFAICS. Instead we are seeing regressions where new kernels > stop working with old dtbs.
I totally agree with you on this point: my patch is not a replacement of yours. I just wanted to point out that we need to fix DT definitions to avoid these kind of issues in the future.
> > I'm going to resend the patch replacing list_add() with list_add_tail(), > with this the mvebu platform would work and there should be no regression > on imx and exynos. > > Please note that specifying dependencies between CCM on imx and the fixed > clocks might not be enough. If the fixed clocks get matched on "fixed-clock" > compatible some clock specifiers (i.e. those using phandle to the CCM) could > get invalid, since the clocks won't get registered by the ccm driver, but by > the regular fixed clock driver. That means a phandle to different node would > need to be used to reference the fixed clock. I'm not sure if this is the case > for imx, but changes may be needed all over various dts files. > In addition, we should make sure the kernel works with current and modified > dtbs. > >> [1] http://lxr.free-electrons.com/source/arch/arm/boot/dts/imx6sl.dtsi#L379 >> [2] http://lxr.free-electrons.com/source/arch/arm/mach-imx/clk-imx6q.c#L151 >> [3] http://lxr.free-electrons.com/source/arch/arm/mach-imx/clk.c#L30
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