Hi Paweł Chmiel,
On 10/25/20 12:43 AM, Paweł Chmiel wrote:
> This clock must be always enabled to allow access to any registers in
> fsys1 CMU. Until proper solution based on runtime PM is applied
> (similar to what was done for Exynos5433), mark that clock as critical
> so it won't be disabled.
>
> It was observed on Samsung Galaxy S6 device (based on Exynos7420), where
> UFS module is probed before pmic used to power that device.
> In this case defer probe was happening and that clock was disabled by
> UFS driver, causing whole boot to hang on next CMU access.
>
> Signed-off-by: Paweł Chmiel <pawel.mikolaj.chm...@gmail.com>
> ---
> drivers/clk/samsung/clk-exynos7.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/clk/samsung/clk-exynos7.c
> b/drivers/clk/samsung/clk-exynos7.c
> index c1ff715e960c..1048d83f097b 100644
> --- a/drivers/clk/samsung/clk-exynos7.c
> +++ b/drivers/clk/samsung/clk-exynos7.c
> @@ -538,7 +538,8 @@ static const struct samsung_gate_clock top1_gate_clks[]
> __initconst = {
> ENABLE_ACLK_TOP13, 28, CLK_SET_RATE_PARENT |
> CLK_IS_CRITICAL, 0),
> GATE(CLK_ACLK_FSYS1_200, "aclk_fsys1_200", "dout_aclk_fsys1_200",
> - ENABLE_ACLK_TOP13, 24, CLK_SET_RATE_PARENT, 0),
> + ENABLE_ACLK_TOP13, 24, CLK_SET_RATE_PARENT |
> + CLK_IS_CRITICAL, 0),
As you commented, in order to keep the always on state,
we can use CLK_IS_CRITICAL. Instead, you can enable the specific clock
with detailed comment on clk-exynos7.c as following merged patches[1][2]:
[1] 67f96ff7c8f0 ("clk: samsung: exynos5420: Keep top G3D clocks enabled")
[2] 0212a0483b0a ("clk: samsung: Keep top BPLL mux on Exynos542x enabled")
The patches[1][2] enable the clock with clk_prepare_enable()
instead of adding CLK_IS_CRITICAL. You can refer to it.
>
> GATE(CLK_SCLK_PHY_FSYS1_26M, "sclk_phy_fsys1_26m",
> "dout_sclk_phy_fsys1_26m", ENABLE_SCLK_TOP1_FSYS11,
>
--
Best Regards,
Chanwoo Choi
Samsung Electronics
