Messages in this thread | | | Date | Wed, 27 Oct 2021 08:21:26 +0100 | From | Mauro Carvalho Chehab <> | Subject | Re: [PATCH 0/2] clk: fix the need of booking clk_ignore_unused=true on embedded devs |
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Stephen/Michael,
Gentile ping.
Regards, Mauro
Em Thu, 7 Oct 2021 14:06:53 +0200 Mauro Carvalho Chehab <mchehab+huawei@kernel.org> escreveu:
> Currently, the only way to boot a Kernel with drivers built as modules on embedded > devices like HiKey 970 is to pass clk_ignore_unused=true as a modprobe parameter. > > There are two separate issues: > > 1. the clk's core calls clk_disable_unused() too early. By the time this > function is called, only the builtin drivers were already probed/initialized. > Drivers built as modules will only be probed afterwards. > > This cause a race condition and boot instability, as the clk core will try > to disable clocks while the drivers built as modules are still being > probed and initialized. > > I suspect that the same problem used to happen at the regulator's core, > as there's a code that waits for 30 seconds before disabling unused > regulators; > > 2. there are some gate clocks defined at HiKey 970 that should always be on, > as otherwise the system will hang, or the filesystem I/O will stop. > > Ps.: > I submitted already 3 or 4 versions of patches for HiKey 970 clock, but > they're all unreliable, due to the race conditions at the clk core due to (1). > > Patch 1 solves the issue with the clk core. > Patch 2 solves the HiKey 970 specific issues. > > Mauro Carvalho Chehab (2): > clk: wait for extra time before disabling unused clocks > clk: clk-hi3670: mark some clocks as CLK_IS_CRITICAL > > drivers/clk/clk.c | 51 +++++++++++++++++++----------- > drivers/clk/hisilicon/clk-hi3670.c | 24 +++++++------- > 2 files changed, 44 insertions(+), 31 deletions(-) >
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