linux-kernel - Re: [PATCH] clk: samsung: fsd: Mark PLL_CAM

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Message-ID: <0d43a00985a815c1869ebc6c441a2aed.sboyd@kernel.org>
Date: Thu, 19 Sep 2024 03:21:02 -0700
From: Stephen Boyd <sboyd@...nel.org>
To: Inbaraj E <inbaraj.e@...sung.com>, alim.akhtar@...sung.com, cw00.choi@...sung.com, krzk@...nel.org, linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org, mturquette@...libre.com, s.nawrocki@...sung.com
Cc: pankaj.dubey@...sung.com, gost.dev@...sung.com, Inbaraj E <inbaraj.e@...sung.com>
Subject: Re: [PATCH] clk: samsung: fsd: Mark PLL_CAM_CSI as critical

Quoting Inbaraj E (2024-09-17 03:10:16)
> PLL_CAM_CSI is the parent clock for the ACLK and PCLK in the CMU_CAM_CSI
> block. When we gate ACLK or PCLK, the clock framework will subsequently
> disables the parent clocks(PLL_CAM_CSI). Disabling PLL_CAM_CSI is causing
> sytem level halt.
> 
> It was observed on FSD SoC, when we gate the ACLK and PCLK during CSI stop
> streaming through pm_runtime_put system is getting halted. So marking
> PLL_CAM_CSI as critical to prevent disabling.
> 
> Signed-off-by: Inbaraj E <inbaraj.e@...sung.com>
> ---

Please add a fixes tag. Although this is likely a band-aid fix because
marking something critical leaves it enabled forever.

>  drivers/clk/samsung/clk-fsd.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/clk/samsung/clk-fsd.c b/drivers/clk/samsung/clk-fsd.c
> index 6f984cfcd33c..b1764aab9429 100644
> --- a/drivers/clk/samsung/clk-fsd.c
> +++ b/drivers/clk/samsung/clk-fsd.c
> @@ -1637,8 +1637,9 @@ static const struct samsung_pll_rate_table pll_cam_csi_rate_table[] __initconst
>  };
>  
>  static const struct samsung_pll_clock cam_csi_pll_clks[] __initconst = {
> -       PLL(pll_142xx, 0, "fout_pll_cam_csi", "fin_pll",
> -           PLL_LOCKTIME_PLL_CAM_CSI, PLL_CON0_PLL_CAM_CSI, pll_cam_csi_rate_table),
> +       __PLL(pll_142xx, 0, "fout_pll_cam_csi", "fin_pll",
> +               CLK_GET_RATE_NOCACHE | CLK_IS_CRITICAL, PLL_LOCKTIME_PLL_CAM_CSI,

Please add a comment indicating that this clk can never turn off because
<insert reason here>.