Am 2014-07-29 16:44, schrieb Arnd Bergmann: > On Tuesday 29 July 2014 16:20:28 Stefan Agner wrote: >> At the end of the boot process, the clock framework might disable >> required main PLL's. So far, this was no issue since drivers >> requested clocks, which are descended of the main PLL's (e.g. >> pll1_pfd1, which provides the system clock). >> >> To archive the full 500MHz system clock, DDR clock need to be a >> descendant of PLL2 rather than PLL1 (DDRC_CLK_SEL set to 0). The >> bootloader sets up the clocks accordingly before making use of >> DDR at all. However, in Linux, there is no driver using PLL2, >> which lead to PLL2 being disabled by the clock framework. >> >> With this patch, we make sure that the main system clock and the >> DDR clock are initially enabled and are kept enabled. >> >> Signed-off-by: Stefan Agner <ste...@agner.ch> >> > > Wouldn't it be better to list this in the DT as a default for > the respective clocks? >
What do you mean by that exactly? Creating a driver for the main PLL's and add device tree entries to instantiate them, along with a property like "boot-enabled" or similar? The approach chosen in this patch is aligned the way it's done for i.MX6 (see arch/arm/mach-imx/clk-imx6q.c). The whole clock module(s) in Vybrid are slightly striped variants found in i.MX6. For now, I would prefer to leave it that way. -- Stefan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
