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Message-ID: <1d09a2c5-4973-340f-fdfc-d4e665c8b55d@gmail.com>
Date: Sun, 11 Aug 2019 21:02:02 +0300
From: Dmitry Osipenko <digetx@...il.com>
To: Sowjanya Komatineni <skomatineni@...dia.com>,
thierry.reding@...il.com, jonathanh@...dia.com, tglx@...utronix.de,
jason@...edaemon.net, marc.zyngier@....com,
linus.walleij@...aro.org, stefan@...er.ch, mark.rutland@....com
Cc: pdeschrijver@...dia.com, pgaikwad@...dia.com, sboyd@...nel.org,
linux-clk@...r.kernel.org, linux-gpio@...r.kernel.org,
jckuo@...dia.com, josephl@...dia.com, talho@...dia.com,
linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
mperttunen@...dia.com, spatra@...dia.com, robh+dt@...nel.org,
devicetree@...r.kernel.org, rjw@...ysocki.net,
viresh.kumar@...aro.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v8 13/21] clk: tegra210: Use fence_udelay during PLLU init
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 <treding@...dia.com>
> Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
> ---
> 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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