Re: [PATCH] clk: imx8m: fix clock tree update of TF-A managed clocks

From: Abel Vesa
Date: Wed Aug 18 2021 - 11:14:49 EST

On 21-08-10 17:14:33, Ahmad Fatoum wrote:
> On the i.MX8M*, the TF-A exposes a SiP (Silicon Provider) service
> for DDR frequency scaling. The imx8m-ddrc-devfreq driver calls the
> SiP and then does clk_set_parent on the DDR muxes to synchronize
> the clock tree.
>
> Since 936c383673b9 ("clk: imx: fix composite peripheral flags"),
> these TF-A managed muxes have SET_PARENT_GATE set, which results
> in imx8m-ddrc-devfreq's clk_set_parent after SiP failing with -EBUSY:
>
> echo 25000000 > userspace/set_freq
> imx8m-ddrc-devfreq 3d400000.memory-controller: failed to set
> dram_apb parent: -16
>
> Fix this by adding a new i.MX composite flag for firmware managed
> clocks, which clears SET_PARENT_GATE.
>
> This is safe to do, because updating the Linux clock tree to reflect
> reality will always be glitch-free.
>
> Fixes: 936c383673b9 ("clk: imx: fix composite peripheral flags")
> Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>

I'm OK with this.

Reviewed-by: Abel Vesa <abel.vesa@xxxxxxx>

BTW, let me know if you are interested in the interconnect+devfreq
(the replacement for NXP's internal busfreq). I have a new version of
that patchset which I intend to send soon for review.

> ---
> To: Abel Vesa <abel.vesa@xxxxxxx>
> To: Michael Turquette <mturquette@xxxxxxxxxxxx>
> To: Stephen Boyd <sboyd@xxxxxxxxxx>
> To: Shawn Guo <shawnguo@xxxxxxxxxx>
> To: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> To: Pengutronix Kernel Team <kernel@xxxxxxxxxxxxxx>
> To: Fabio Estevam <festevam@xxxxxxxxx>
> To: NXP Linux Team <linux-imx@xxxxxxx>
> To: Peng Fan <peng.fan@xxxxxxx>
> To: Leonard Crestez <leonard.crestez@xxxxxxx>
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: linux-clk@xxxxxxxxxxxxxxx
> ---
> drivers/clk/imx/clk-composite-8m.c | 3 ++-
> drivers/clk/imx/clk-imx8mm.c | 7 ++++---
> drivers/clk/imx/clk-imx8mn.c | 7 ++++---
> drivers/clk/imx/clk-imx8mq.c | 7 ++++---
> drivers/clk/imx/clk.h | 16 ++++++++++++++--
> 5 files changed, 28 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/clk/imx/clk-composite-8m.c b/drivers/clk/imx/clk-composite-8m.c
> index 2c309e3dc8e3..04e728538cef 100644
> --- a/drivers/clk/imx/clk-composite-8m.c
> +++ b/drivers/clk/imx/clk-composite-8m.c
> @@ -216,7 +216,8 @@ struct clk_hw *imx8m_clk_hw_composite_flags(const char *name,
> div->width = PCG_PREDIV_WIDTH;
> divider_ops = &imx8m_clk_composite_divider_ops;
> mux_ops = &clk_mux_ops;
> - flags |= CLK_SET_PARENT_GATE;
> + if (!(composite_flags & IMX_COMPOSITE_FW_MANAGED))
> + flags |= CLK_SET_PARENT_GATE;
> }
>
> div->lock = &imx_ccm_lock;
> diff --git a/drivers/clk/imx/clk-imx8mm.c b/drivers/clk/imx/clk-imx8mm.c
> index f1919fafb124..73cc9805ec59 100644
> --- a/drivers/clk/imx/clk-imx8mm.c
> +++ b/drivers/clk/imx/clk-imx8mm.c
> @@ -470,10 +470,11 @@ static int imx8mm_clocks_probe(struct platform_device *pdev)
>
> /*
> * DRAM clocks are manipulated from TF-A outside clock framework.
> - * Mark with GET_RATE_NOCACHE to always read div value from hardware
> + * The fw_managed helper sets GET_RATE_NOCACHE and clears SET_PARENT_GATE
> + * as div value should always be read from hardware
> */
> - hws[IMX8MM_CLK_DRAM_ALT] = __imx8m_clk_hw_composite("dram_alt", imx8mm_dram_alt_sels, base + 0xa000, CLK_GET_RATE_NOCACHE);
> - hws[IMX8MM_CLK_DRAM_APB] = __imx8m_clk_hw_composite("dram_apb", imx8mm_dram_apb_sels, base + 0xa080, CLK_IS_CRITICAL | CLK_GET_RATE_NOCACHE);
> + hws[IMX8MM_CLK_DRAM_ALT] = imx8m_clk_hw_fw_managed_composite("dram_alt", imx8mm_dram_alt_sels, base + 0xa000);
> + hws[IMX8MM_CLK_DRAM_APB] = imx8m_clk_hw_fw_managed_composite_critical("dram_apb", imx8mm_dram_apb_sels, base + 0xa080);
>
> /* IP */
> hws[IMX8MM_CLK_VPU_G1] = imx8m_clk_hw_composite("vpu_g1", imx8mm_vpu_g1_sels, base + 0xa100);
> diff --git a/drivers/clk/imx/clk-imx8mn.c b/drivers/clk/imx/clk-imx8mn.c
> index 88f6630cd472..0a76f969b28b 100644
> --- a/drivers/clk/imx/clk-imx8mn.c
> +++ b/drivers/clk/imx/clk-imx8mn.c
> @@ -453,10 +453,11 @@ static int imx8mn_clocks_probe(struct platform_device *pdev)
>
> /*
> * DRAM clocks are manipulated from TF-A outside clock framework.
> - * Mark with GET_RATE_NOCACHE to always read div value from hardware
> + * The fw_managed helper sets GET_RATE_NOCACHE and clears SET_PARENT_GATE
> + * as div value should always be read from hardware
> */
> - hws[IMX8MN_CLK_DRAM_ALT] = __imx8m_clk_hw_composite("dram_alt", imx8mn_dram_alt_sels, base + 0xa000, CLK_GET_RATE_NOCACHE);
> - hws[IMX8MN_CLK_DRAM_APB] = __imx8m_clk_hw_composite("dram_apb", imx8mn_dram_apb_sels, base + 0xa080, CLK_IS_CRITICAL | CLK_GET_RATE_NOCACHE);
> + hws[IMX8MN_CLK_DRAM_ALT] = imx8m_clk_hw_fw_managed_composite("dram_alt", imx8mn_dram_alt_sels, base + 0xa000);
> + hws[IMX8MN_CLK_DRAM_APB] = imx8m_clk_hw_fw_managed_composite_critical("dram_apb", imx8mn_dram_apb_sels, base + 0xa080);
>
> hws[IMX8MN_CLK_DISP_PIXEL] = imx8m_clk_hw_composite("disp_pixel", imx8mn_disp_pixel_sels, base + 0xa500);
> hws[IMX8MN_CLK_SAI2] = imx8m_clk_hw_composite("sai2", imx8mn_sai2_sels, base + 0xa600);
> diff --git a/drivers/clk/imx/clk-imx8mq.c b/drivers/clk/imx/clk-imx8mq.c
> index c491bc9c61ce..83cc2b1c3294 100644
> --- a/drivers/clk/imx/clk-imx8mq.c
> +++ b/drivers/clk/imx/clk-imx8mq.c
> @@ -449,11 +449,12 @@ static int imx8mq_clocks_probe(struct platform_device *pdev)
>
> /*
> * DRAM clocks are manipulated from TF-A outside clock framework.
> - * Mark with GET_RATE_NOCACHE to always read div value from hardware
> + * The fw_managed helper sets GET_RATE_NOCACHE and clears SET_PARENT_GATE
> + * as div value should always be read from hardware
> */
> hws[IMX8MQ_CLK_DRAM_CORE] = imx_clk_hw_mux2_flags("dram_core_clk", base + 0x9800, 24, 1, imx8mq_dram_core_sels, ARRAY_SIZE(imx8mq_dram_core_sels), CLK_IS_CRITICAL);
> - hws[IMX8MQ_CLK_DRAM_ALT] = __imx8m_clk_hw_composite("dram_alt", imx8mq_dram_alt_sels, base + 0xa000, CLK_GET_RATE_NOCACHE);
> - hws[IMX8MQ_CLK_DRAM_APB] = __imx8m_clk_hw_composite("dram_apb", imx8mq_dram_apb_sels, base + 0xa080, CLK_IS_CRITICAL | CLK_GET_RATE_NOCACHE);
> + hws[IMX8MQ_CLK_DRAM_ALT] = imx8m_clk_hw_fw_managed_composite("dram_alt", imx8mq_dram_alt_sels, base + 0xa000);
> + hws[IMX8MQ_CLK_DRAM_APB] = imx8m_clk_hw_fw_managed_composite_critical("dram_apb", imx8mq_dram_apb_sels, base + 0xa080);
>
> /* IP */
> hws[IMX8MQ_CLK_VPU_G1] = imx8m_clk_hw_composite("vpu_g1", imx8mq_vpu_g1_sels, base + 0xa100);
> diff --git a/drivers/clk/imx/clk.h b/drivers/clk/imx/clk.h
> index 7571603bee23..e144f983fd8c 100644
> --- a/drivers/clk/imx/clk.h
> +++ b/drivers/clk/imx/clk.h
> @@ -530,8 +530,9 @@ struct clk_hw *imx_clk_hw_cpu(const char *name, const char *parent_name,
> struct clk *div, struct clk *mux, struct clk *pll,
> struct clk *step);
>
> -#define IMX_COMPOSITE_CORE BIT(0)
> -#define IMX_COMPOSITE_BUS BIT(1)
> +#define IMX_COMPOSITE_CORE BIT(0)
> +#define IMX_COMPOSITE_BUS BIT(1)
> +#define IMX_COMPOSITE_FW_MANAGED BIT(2)
>
> struct clk_hw *imx8m_clk_hw_composite_flags(const char *name,
> const char * const *parent_names,
> @@ -567,6 +568,17 @@ struct clk_hw *imx8m_clk_hw_composite_flags(const char *name,
> ARRAY_SIZE(parent_names), reg, 0, \
> flags | CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE)
>
> +#define __imx8m_clk_hw_fw_managed_composite(name, parent_names, reg, flags) \
> + imx8m_clk_hw_composite_flags(name, parent_names, \
> + ARRAY_SIZE(parent_names), reg, IMX_COMPOSITE_FW_MANAGED, \
> + flags | CLK_GET_RATE_NOCACHE | CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE)
> +
> +#define imx8m_clk_hw_fw_managed_composite(name, parent_names, reg) \
> + __imx8m_clk_hw_fw_managed_composite(name, parent_names, reg, 0)
> +
> +#define imx8m_clk_hw_fw_managed_composite_critical(name, parent_names, reg) \
> + __imx8m_clk_hw_fw_managed_composite(name, parent_names, reg, CLK_IS_CRITICAL)
> +
> #define __imx8m_clk_composite(name, parent_names, reg, flags) \
> to_clk(__imx8m_clk_hw_composite(name, parent_names, reg, flags))
>
> --
> 2.30.2
>