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Mon, 12 Aug 2019 13:28:17 -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> <1779e92b-fa4d-68ab-9218-51970eee1ec5@gmail.com> From: Dmitry Osipenko Message-ID: <232688c1-d47b-771d-a768-07e722488fa8@gmail.com> Date: Mon, 12 Aug 2019 23:28:15 +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: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-clk-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org 12.08.2019 22:03, Sowjanya Komatineni пишет: > > On 8/12/19 11:19 AM, Dmitry Osipenko wrote: >> 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 > > All CLK_OUT_ENB* registers are already defined in clk driver and also periph_regs includes > all of these to use. > > To write value to enable all clocks directly without array, it need total 7 individual > register writes for Tegra210. Also when suspend/resume is implemented for other prior > tegras, they need to do same in tegra clock driver. > > Reason I had this in clock driver is, this can be used by all tegra clock drivers and just > can pass valid clocks values. > > But doing individual register write with direct hard code values in corresponding tegra > clock driver is preferred still, will update so in next revision and will move all the > CLK_OUT_ENB* register defines to tegra/clk.h > > Currently RST_DEVICES & CLK_OUT_ENB are all in tegra/clk.c Yes, it should be a bit more clear to share these defines. Also, please define the "valid" bitmasks with something like TEGRA210_DEVICES_MASK_L.