On Fri, Oct 20, 2017 at 11:20:24AM +0100, Jon Hunter wrote: > > On 19/10/17 19:42, Nicolin Chen wrote: > > On Thu, Oct 19, 2017 at 11:44:22AM +0200, Thierry Reding wrote: > >>>> Below is the call trace of tegra210_init_pllu() function: > >>>> start_kernel() > >>>> -> time_init() > >>>> --> of_clk_init() > >>>> ---> tegra210_clock_init() > >>>> ----> tegra210_pll_init() > >>>> -----> tegra210_init_pllu() > > > >> I'm wondering why we're not seeing a splat for this. Usually the kernel > >> will warn if you sleep during atomic context. Does this mean we're just > >> not hitting that case? > > > > Yes. > > > >> readx_poll_timeout() has a might_sleep_if(), and > >> therefore it should always cause the splat. > > > > That's true as long as CONFIG_DEBUG_ATOMIC_SLEEP is enabled locally. > > > >> Any ideas why this has gone unnoticed for all this time? > > > > We can see in the tegra210_init_pllu() function that it'll not call > > tegra210_enable_pllu() if pllu is already enabled (by bootloader). > > I was thinking that same and so I clobbered the PLLU enable bit with > u-boot, however, then the kernel appears to hang on boot when enabling > the PLL. So although this is probably a separate issue, I am curious if > you have booted the mainline with the PLLU disabled? I am not sure if clearing the enable bit only would work. But the test below should be able to verify the situation -- setting the PLLU_BASE register to its reset value. diff --git a/drivers/clk/tegra/clk-tegra210.c b/drivers/clk/tegra/clk-tegra210.c index ea695c4..2279373 100644 --- a/drivers/clk/tegra/clk-tegra210.c +++ b/drivers/clk/tegra/clk-tegra210.c @@ -2602,6 +2602,7 @@ static int tegra210_init_pllu(void) u32 reg; int err; + writel_relaxed(0x1011902, clk_base + PLLU_BASE); tegra210_pllu_set_defaults(&pll_u_vco_params); /* skip initialization when pllu is in hw controlled mode */ reg = readl_relaxed(clk_base + PLLU_BASE); -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
