The Exynos850 APM co-processor relies on the I3C bus to communicate with
the PMIC. Currently, there is no dedicated PMIC consumer driver managing
these clocks, so the clock subsystem automatically gates them during the
initialisation. Once gated, any subsequent ACPM communication with APM
results in timeouts.

As a temporary workaround (and let's hope it doesn't become permanent),
mark both `gout_i3c_pclk` and `gout_i3c_sclk` as CLK_IS_CRITICAL ones to
prevent the clock subsystem from disabling them. This makes the ACPM
communication functional. This workaround should be reverted once a
proper ACPM PMIC driver is implemented to manage these clocks.

Cc: Sam Protsenko <semen.protsenko@linaro.org>
Cc: Tudor Ambarus <tudor.ambarus@linaro.org>
Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
---
 drivers/clk/samsung/clk-exynos850.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/samsung/clk-exynos850.c b/drivers/clk/samsung/clk-exynos850.c
index eb9c80b60225efa33d85f5f3c284eb8a63a48015..b143a42293f5a154f53a86d4e97e17a3e61164f3 100644
--- a/drivers/clk/samsung/clk-exynos850.c
+++ b/drivers/clk/samsung/clk-exynos850.c
@@ -686,10 +686,11 @@ static const struct samsung_gate_clock apm_gate_clks[] __initconst = {
 	     CLK_CON_GAT_GOUT_APM_APBIF_RTC_PCLK, 21, 0, 0),
 	GATE(CLK_GOUT_TOP_RTC_PCLK, "gout_top_rtc_pclk", "dout_apm_bus",
 	     CLK_CON_GAT_GOUT_APM_APBIF_TOP_RTC_PCLK, 21, 0, 0),
+	/* TODO: Should be dealt with or enabled in PMIC ACPM driver */
 	GATE(CLK_GOUT_I3C_PCLK, "gout_i3c_pclk", "dout_apm_bus",
-	     CLK_CON_GAT_GOUT_APM_I3C_APM_PMIC_I_PCLK, 21, 0, 0),
+	     CLK_CON_GAT_GOUT_APM_I3C_APM_PMIC_I_PCLK, 21, CLK_IS_CRITICAL, 0),
 	GATE(CLK_GOUT_I3C_SCLK, "gout_i3c_sclk", "mout_apm_i3c",
-	     CLK_CON_GAT_GOUT_APM_I3C_APM_PMIC_I_SCLK, 21, 0, 0),
+	     CLK_CON_GAT_GOUT_APM_I3C_APM_PMIC_I_SCLK, 21, CLK_IS_CRITICAL, 0),
 	GATE(CLK_GOUT_SPEEDY_PCLK, "gout_speedy_pclk", "dout_apm_bus",
 	     CLK_CON_GAT_GOUT_APM_SPEEDY_APM_PCLK, 21, 0, 0),
 	/* TODO: Should be enabled in GPIO driver (or made CLK_IS_CRITICAL) */

---
base-commit: 0787c45ea08a13b5482e701fabc741877cf681f6
change-id: 20260430-exynos850-i3c-criticalclocks-dcabb78bf154

Best regards,
-- 
Alexey Klimov <alexey.klimov@linaro.org>

On Thu, 30 Apr 2026 12:53:27 +0100, Alexey Klimov wrote:
> The Exynos850 APM co-processor relies on the I3C bus to communicate with
> the PMIC. Currently, there is no dedicated PMIC consumer driver managing
> these clocks, so the clock subsystem automatically gates them during the
> initialisation. Once gated, any subsequent ACPM communication with APM
> results in timeouts.
> 
> As a temporary workaround (and let's hope it doesn't become permanent),
> mark both `gout_i3c_pclk` and `gout_i3c_sclk` as CLK_IS_CRITICAL ones to
> prevent the clock subsystem from disabling them. This makes the ACPM
> communication functional. This workaround should be reverted once a
> proper ACPM PMIC driver is implemented to manage these clocks.
> 
> [...]

Applied, thanks!

[1/1] clk: samsung: exynos850: mark APM I3C clocks as critical
      (no commit info)

Best regards,
-- 
Krzysztof Kozlowski <krzk@kernel.org>

On Thu, Apr 30, 2026 at 6:53 AM Alexey Klimov <alexey.klimov@linaro.org> wrote:
>
> The Exynos850 APM co-processor relies on the I3C bus to communicate with
> the PMIC. Currently, there is no dedicated PMIC consumer driver managing
> these clocks, so the clock subsystem automatically gates them during the
> initialisation. Once gated, any subsequent ACPM communication with APM
> results in timeouts.
>
> As a temporary workaround (and let's hope it doesn't become permanent),
> mark both `gout_i3c_pclk` and `gout_i3c_sclk` as CLK_IS_CRITICAL ones to
> prevent the clock subsystem from disabling them. This makes the ACPM
> communication functional. This workaround should be reverted once a
> proper ACPM PMIC driver is implemented to manage these clocks.
>
> Cc: Sam Protsenko <semen.protsenko@linaro.org>
> Cc: Tudor Ambarus <tudor.ambarus@linaro.org>
> Signed-off-by: Alexey Klimov <alexey.klimov@linaro.org>
> ---

Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>

>  drivers/clk/samsung/clk-exynos850.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/samsung/clk-exynos850.c b/drivers/clk/samsung/clk-exynos850.c
> index eb9c80b60225efa33d85f5f3c284eb8a63a48015..b143a42293f5a154f53a86d4e97e17a3e61164f3 100644
> --- a/drivers/clk/samsung/clk-exynos850.c
> +++ b/drivers/clk/samsung/clk-exynos850.c
> @@ -686,10 +686,11 @@ static const struct samsung_gate_clock apm_gate_clks[] __initconst = {
>              CLK_CON_GAT_GOUT_APM_APBIF_RTC_PCLK, 21, 0, 0),
>         GATE(CLK_GOUT_TOP_RTC_PCLK, "gout_top_rtc_pclk", "dout_apm_bus",
>              CLK_CON_GAT_GOUT_APM_APBIF_TOP_RTC_PCLK, 21, 0, 0),
> +       /* TODO: Should be dealt with or enabled in PMIC ACPM driver */
>         GATE(CLK_GOUT_I3C_PCLK, "gout_i3c_pclk", "dout_apm_bus",
> -            CLK_CON_GAT_GOUT_APM_I3C_APM_PMIC_I_PCLK, 21, 0, 0),
> +            CLK_CON_GAT_GOUT_APM_I3C_APM_PMIC_I_PCLK, 21, CLK_IS_CRITICAL, 0),
>         GATE(CLK_GOUT_I3C_SCLK, "gout_i3c_sclk", "mout_apm_i3c",
> -            CLK_CON_GAT_GOUT_APM_I3C_APM_PMIC_I_SCLK, 21, 0, 0),
> +            CLK_CON_GAT_GOUT_APM_I3C_APM_PMIC_I_SCLK, 21, CLK_IS_CRITICAL, 0),
>         GATE(CLK_GOUT_SPEEDY_PCLK, "gout_speedy_pclk", "dout_apm_bus",
>              CLK_CON_GAT_GOUT_APM_SPEEDY_APM_PCLK, 21, 0, 0),
>         /* TODO: Should be enabled in GPIO driver (or made CLK_IS_CRITICAL) */
>
> ---
> base-commit: 0787c45ea08a13b5482e701fabc741877cf681f6
> change-id: 20260430-exynos850-i3c-criticalclocks-dcabb78bf154
>
> Best regards,
> --
> Alexey Klimov <alexey.klimov@linaro.org>
>

Reviewed-by: Tudor Ambarus <tudor.ambarus@linaro.org>