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Mon, 12 Aug 2019 09:25:52 -0700 (PDT) Subject: Re: [PATCH v8 14/21] clk: tegra210: Add suspend and resume support To: Sowjanya Komatineni Cc: thierry.reding@gmail.com, jonathanh@nvidia.com, tglx@linutronix.de, jason@lakedaemon.net, marc.zyngier@arm.com, linus.walleij@linaro.org, stefan@agner.ch, mark.rutland@arm.com, pdeschrijver@nvidia.com, pgaikwad@nvidia.com, sboyd@kernel.org, linux-clk@vger.kernel.org, linux-gpio@vger.kernel.org, jckuo@nvidia.com, josephl@nvidia.com, talho@nvidia.com, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, mperttunen@nvidia.com, spatra@nvidia.com, robh+dt@kernel.org, devicetree@vger.kernel.org, rjw@rjwysocki.net, viresh.kumar@linaro.org, linux-pm@vger.kernel.org References: <1565308020-31952-1-git-send-email-skomatineni@nvidia.com> <1565308020-31952-15-git-send-email-skomatineni@nvidia.com> <7d101ec9-c559-8b40-1764-6bf67a9c7a7a@nvidia.com> <4397de5d-772d-2b04-5f87-b2988f6c96c8@gmail.com> <805a825e-f19d-d056-83eb-8ed1cb1c089c@nvidia.com> From: Dmitry Osipenko Message-ID: Date: Mon, 12 Aug 2019 19:25:50 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <805a825e-f19d-d056-83eb-8ed1cb1c089c@nvidia.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-gpio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org 11.08.2019 22:15, Sowjanya Komatineni пишет: > > On 8/11/19 10:39 AM, Dmitry Osipenko wrote: >> 09.08.2019 21:40, Sowjanya Komatineni пишет: >>> On 8/9/19 11:18 AM, Dmitry Osipenko wrote: >>>> 09.08.2019 19:19, Sowjanya Komatineni пишет: >>>>> On 8/9/19 6:56 AM, Dmitry Osipenko wrote: >>>>>> 09.08.2019 2:46, Sowjanya Komatineni пишет: >>>>>>> This patch adds support for clk: tegra210: suspend-resume. >>>>>>> >>>>>>> All the CAR controller settings are lost on suspend when core >>>>>>> power goes off. >>>>>>> >>>>>>> This patch has implementation for saving and restoring all PLLs >>>>>>> and clocks context during system suspend and resume to have the >>>>>>> clocks back to same state for normal operation. >>>>>>> >>>>>>> Clock driver suspend and resume are registered as syscore_ops as clocks >>>>>>> restore need to happen before the other drivers resume to have all their >>>>>>> clocks back to the same state as before suspend. >>>>>>> >>>>>>> Signed-off-by: Sowjanya Komatineni >>>>>>> --- >>>>>>>    drivers/clk/tegra/clk-tegra210.c | 103 +++++++++++++++++++++++++++++++++++++-- >>>>>>>    drivers/clk/tegra/clk.c          |  64 ++++++++++++++++++++++++ >>>>>>>    drivers/clk/tegra/clk.h          |   3 ++ >>>>>>>    3 files changed, 166 insertions(+), 4 deletions(-) >>>>>>> >>>>>>> diff --git a/drivers/clk/tegra/clk-tegra210.c b/drivers/clk/tegra/clk-tegra210.c >>>>>>> index 998bf60b219a..8dd6f4f4debb 100644 >>>>>>> --- a/drivers/clk/tegra/clk-tegra210.c >>>>>>> +++ b/drivers/clk/tegra/clk-tegra210.c >>>>>>> @@ -9,13 +9,13 @@ >>>>>>>    #include >>>>>>>    #include >>>>>>>    #include >>>>>>> +#include >>>>>>>    #include >>>>>>>    #include >>>>>>>    #include >>>>>>>    #include >>>>>>>    #include >>>>>>>    #include >>>>>>> -#include >>>>>>>    #include >>>>>>>    #include >>>>>>>    @@ -220,11 +220,15 @@ >>>>>>>    #define CLK_M_DIVISOR_SHIFT 2 >>>>>>>    #define CLK_M_DIVISOR_MASK 0x3 >>>>>>>    +#define CLK_MASK_ARM    0x44 >>>>>>> +#define MISC_CLK_ENB    0x48 >>>>>>> + >>>>>>>    #define RST_DFLL_DVCO 0x2f4 >>>>>>>    #define DVFS_DFLL_RESET_SHIFT 0 >>>>>>>      #define CLK_RST_CONTROLLER_RST_DEV_Y_SET 0x2a8 >>>>>>>    #define CLK_RST_CONTROLLER_RST_DEV_Y_CLR 0x2ac >>>>>>> +#define CPU_SOFTRST_CTRL 0x380 >>>>>>>      #define LVL2_CLK_GATE_OVRA 0xf8 >>>>>>>    #define LVL2_CLK_GATE_OVRC 0x3a0 >>>>>>> @@ -2825,6 +2829,7 @@ static int tegra210_enable_pllu(void) >>>>>>>        struct tegra_clk_pll_freq_table *fentry; >>>>>>>        struct tegra_clk_pll pllu; >>>>>>>        u32 reg; >>>>>>> +    int ret; >>>>>>>          for (fentry = pll_u_freq_table; fentry->input_rate; fentry++) { >>>>>>>            if (fentry->input_rate == pll_ref_freq) >>>>>>> @@ -2853,9 +2858,14 @@ static int tegra210_enable_pllu(void) >>>>>>>        reg |= PLL_ENABLE; >>>>>>>        writel(reg, clk_base + PLLU_BASE); >>>>>>>    -    readl_relaxed_poll_timeout_atomic(clk_base + PLLU_BASE, reg, >>>>>>> -                      reg & PLL_BASE_LOCK, 2, 1000); >>>>>>> -    if (!(reg & PLL_BASE_LOCK)) { >>>>>>> +    /* >>>>>>> +     * During clocks resume, same PLLU init and enable sequence get >>>>>>> +     * executed. So, readx_poll_timeout_atomic can't be used here as it >>>>>>> +     * uses ktime_get() and timekeeping resume doesn't happen by that >>>>>>> +     * time. So, using tegra210_wait_for_mask for PLL LOCK. >>>>>>> +     */ >>>>>>> +    ret = tegra210_wait_for_mask(&pllu, PLLU_BASE, PLL_BASE_LOCK); >>>>>>> +    if (ret) { >>>>>>>            pr_err("Timed out waiting for PLL_U to lock\n"); >>>>>>>            return -ETIMEDOUT; >>>>>>>        } >>>>>>> @@ -3288,6 +3298,84 @@ static void tegra210_disable_cpu_clock(u32 cpu) >>>>>>>    } >>>>>>>      #ifdef CONFIG_PM_SLEEP >>>>>>> +/* >>>>>>> + * This array lists mask values for each peripheral clk bank >>>>>>> + * to mask out reserved bits during the clocks state restore >>>>>>> + * on SC7 resume to prevent accidental writes to these reserved >>>>>>> + * bits. >>>>>>> + */ >>>>>>> +static u32 periph_clk_rsvd_mask[TEGRA210_CAR_BANK_COUNT] = { >>>>>> Should be more natural to have a "valid_mask" instead of "rsvd_mask". >>>>>> >>>>>> What's actually wrong with touching of the reserved bits? They must be NO-OP.. or the >>>>>> reserved bits are actually some kind of "secret" bits? If those bits have some use-case >>>>>> outside of Silicon HW (like FPGA simulation), then this doesn't matter for upstream >>>>>> and you >>>>>> have to keep the workaround locally in the downstream kernel or whatever. >>>>> Will rename as valid_mask. >>>>> >>>>> some bits in these registers are undefined and is not good to write to these bits as they >>>>> can cause pslverr. >>>> Okay, it should be explained in the comment. >>>> >>>> Is it possible to disable trapping of changing the undefined bits? >>> No its internal to design >> Okay. >> >> Also, what about to move the valid_mask into struct tegra_clk_periph_regs? > > No, we cannot move to tegra_clk_periph_regs as its in tegra/clk.c and is common for all tegra. > > Reserved bits are different on tegra chips so should come from Tegra chip specific clock > driver like > > clk-tegra210 for Tegra210. Could you please check whether the reserved bits are RAZ (read as zero)? [snip]