09.08.2019 2:46, Sowjanya Komatineni пишет:
> This patch uses fence_udelay rather than udelay during PLLU
> initialization to ensure writes to clock registers happens before
> waiting for specified delay.
> 
> Acked-by: Thierry Reding <[email protected]>
> Signed-off-by: Sowjanya Komatineni <[email protected]>
> ---
>  drivers/clk/tegra/clk-tegra210.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/clk/tegra/clk-tegra210.c 
> b/drivers/clk/tegra/clk-tegra210.c
> index 4721ee030d1c..998bf60b219a 100644
> --- a/drivers/clk/tegra/clk-tegra210.c
> +++ b/drivers/clk/tegra/clk-tegra210.c
> @@ -2841,7 +2841,7 @@ static int tegra210_enable_pllu(void)
>       reg = readl_relaxed(clk_base + pllu.params->ext_misc_reg[0]);
>       reg &= ~BIT(pllu.params->iddq_bit_idx);
>       writel_relaxed(reg, clk_base + pllu.params->ext_misc_reg[0]);
> -     udelay(5);
> +     fence_udelay(5, clk_base);
>  
>       reg = readl_relaxed(clk_base + PLLU_BASE);
>       reg &= ~GENMASK(20, 0);
> @@ -2849,7 +2849,7 @@ static int tegra210_enable_pllu(void)
>       reg |= fentry->n << 8;
>       reg |= fentry->p << 16;
>       writel(reg, clk_base + PLLU_BASE);
> -     udelay(1);
> +     fence_udelay(1, clk_base);
>       reg |= PLL_ENABLE;
>       writel(reg, clk_base + PLLU_BASE);
>  
> @@ -2895,12 +2895,12 @@ static int tegra210_init_pllu(void)
>               reg = readl_relaxed(clk_base + XUSB_PLL_CFG0);
>               reg &= ~XUSB_PLL_CFG0_PLLU_LOCK_DLY_MASK;
>               writel_relaxed(reg, clk_base + XUSB_PLL_CFG0);
> -             udelay(1);
> +             fence_udelay(1, clk_base);
>  
>               reg = readl_relaxed(clk_base + PLLU_HW_PWRDN_CFG0);
>               reg |= PLLU_HW_PWRDN_CFG0_SEQ_ENABLE;
>               writel_relaxed(reg, clk_base + PLLU_HW_PWRDN_CFG0);
> -             udelay(1);
> +             fence_udelay(1, clk_base);
>  
>               reg = readl_relaxed(clk_base + PLLU_BASE);
>               reg &= ~PLLU_BASE_CLKENABLE_USB;
> 

The clk_base corresponds to the RESET controller's part of Clock-and-Reset 
hardware, is it
okay to read-back the RST register and not the clock for the fencing?

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