Messages in this thread | | | Date | Thu, 14 Feb 2013 16:21:00 +0530 | From | Laxman Dewangan <> | Subject | Re: [PATCH V2] clk: tegra: initialise parent of uart clocks |
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On Wednesday 13 February 2013 10:04 PM, Stephen Warren wrote: > On 02/13/2013 12:02 AM, Laxman Dewangan wrote: >> On Tuesday 12 February 2013 11:16 PM, Stephen Warren wrote: >>> On 02/12/2013 08:17 AM, Laxman Dewangan wrote: >>>> Initialise the parent of UARTs to PLLP and disabling clock by >>>> default. >>> This patch wasn't tested, was it? Without the patch I just sent titled >>> "ARM: tegra: remove clock-frequency properties from serial nodes", the >>> UART clocks get turned off and the console breaks. >> I tested this in next-20130212 where "clock-frequency" is there in >> tegra30.dtsi file. > I tested on Cardhu/Tegra30 (I'd previously only tested on > Harmony/Tegra20), and I see the exact same problem; the clock core turns > off the UART clock and the system hangs. > > Are you sure you don't have any other local patches that somehow keep > the UART clock on (e.g. disabling clk_disable_unused, calling clk_get() > on the UART clock somewhere else, have the Tegra HS UART driver enabled > on the console port for testing which perhaps does an unconditional > clk_get). Are you sure you're testing with U-Boot rather than our binary > bootloader; who knows what kind of voodoo that does to clocks. > > Note: I tested: a merge of arm-soc/for-next and Tegra's for-next branch, > with my patch to remove the clock-frequency properties reverted, plus a > fix for the boot crash ("clockevents: fix generic broadcast for > FEAT_C3STOP"). > >> If you remove this from dts file at all then it will not work as there >> is no execution path to call the clk_prepare_enable(). >> >> of_serial.c file: >> if (of_property_read_u32(np, "clock-frequency", &clk)) { > That returns 0 if the property is present (so doesn't get/enable the > clock), and an error code if the property is missing (so does get/enable > the clock).
Ahha..Yes, got it. I tested this in next-20130212 with the maintainer's patch for broadcast, reverting one change "OF: convert devtree lock from rw_lock to raw spinlock" and uart clock change. The system was booting but not reaching to login. I was assumign that it may be the issue with other reason as I saw the uart log.
After taking your patch for removing clock-freq and this patch, the system booted to login prompt means it is working fine.
So I was wrong when telling clock-frequency is required. Actually it should not be to work properly.
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