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Mon, 12 Aug 2019 11:19:34 -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> <931b027d-fdf3-220b-167a-4177fa917781@nvidia.com> From: Dmitry Osipenko Message-ID: <1779e92b-fa4d-68ab-9218-51970eee1ec5@gmail.com> Date: Mon, 12 Aug 2019 21:19:32 +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: <931b027d-fdf3-220b-167a-4177fa917781@nvidia.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org 12.08.2019 20:28, Sowjanya Komatineni пишет: > > On 8/12/19 9:25 AM, Dmitry Osipenko wrote: >> 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] > > yes all reserved bits of clk_enb register is 0. This should not be set to 1. > > As I will be changing to variable name to valid_mask instead of reserved mask, will also > change values to valid mask so it can be used directly to write to clk_enb for enabling all > peripherals clks. > It looks to me that the tegra_clk_periph_force_on() could be made local to the clk-tegra210.c and then the raw clk_enb values could be written directly instead of having the clk_enb[] array, probably that will be a bit cleaner.