Date:   Thu, 6 Jun 2019 12:13:18 -0700
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     Stephen Boyd <sboyd@...nel.org>, <jason@...edaemon.net>,
        <jonathanh@...dia.com>, <linus.walleij@...aro.org>,
        <marc.zyngier@....com>, <mark.rutland@....com>, <stefan@...er.ch>,
        <tglx@...utronix.de>, <thierry.reding@...il.com>
CC:     <pdeschrijver@...dia.com>, <pgaikwad@...dia.com>,
        <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>
Subject: Re: [PATCH V2 07/12] clk: tegra: support for Tegra210 clocks
 suspend-resume


On 6/6/19 11:17 AM, Stephen Boyd wrote:
> Quoting Sowjanya Komatineni (2019-05-28 16:08:51)
>> @@ -3381,6 +3398,367 @@ static struct tegra_clk_init_table init_table[] __initdata = {
>>          { TEGRA210_CLK_CLK_MAX, TEGRA210_CLK_CLK_MAX, 0, 0 },
>>   };
>>   
>> +#ifdef CONFIG_PM_SLEEP
>> +static unsigned long pll_c_rate, pll_c2_rate, pll_c3_rate, pll_x_rate;
>> +static unsigned long pll_c4_rate, pll_d2_rate, pll_dp_rate;
>> +static unsigned long pll_re_vco_rate, pll_d_rate, pll_a_rate, pll_a1_rate;
>> +static unsigned long pll_c_out1_rate;
>> +static unsigned long pll_a_out0_rate, pll_c4_out3_rate;
>> +static unsigned long pll_p_out_rate[5];
>> +static unsigned long pll_u_out1_rate, pll_u_out2_rate;
>> +static unsigned long pll_mb_rate;
>> +static u32 pll_m_v;
>> +static u32 pll_p_outa, pll_p_outb;
>> +static u32 pll_re_out_div, pll_re_out_1;
>> +static u32 cpu_softrst_ctx[3];
>> +static u32 cclkg_burst_policy_ctx[2];
>> +static u32 cclklp_burst_policy_ctx[2];
>> +static u32 sclk_burst_policy_ctx[3];
>> +static u32 sclk_ctx, spare_ctx, misc_clk_enb_ctx, clk_arm_ctx;
> This is a lot of state to maintain globally. Can it go into a container
> struct so we can get docs and understand what's going on a little
> better?
>
Will revisit and change in next version along with using clk driver 
save_context and restore_context callbacks.
>> +
>> +static struct platform_device *dfll_pdev;
>> +#define car_readl(_base, _off) \
>> +       readl_relaxed(clk_base + (_base) + ((_off) * 4))
>> +#define car_writel(_val, _base, _off) \
>> +       writel_relaxed(_val, clk_base + (_base) + ((_off) * 4))
>> +
>> +static u32 *periph_clk_src_ctx;
>> +struct periph_source_bank {
>> +       u32 start;
>> +       u32 end;
> Do these need to be u32 or could they be u16?
WIll update in next version of this patch
>> +};
>> +
>> +static struct periph_source_bank periph_srcs[] = {
> Can this be const?
WIll update in next version of this patch
>
>> +       [0] = {
>> +               .start = 0x100,
>> +               .end = 0x198,
>> +       },
>> +       [1] = {
>> +               .start = 0x1a0,
>> +               .end = 0x1f8,
>> +       },
>> +       [2] = {
>> +               .start = 0x3b4,
>> +               .end = 0x42c,
>> +       },
>> +       [3] = {
>> +               .start = 0x49c,
>> +               .end = 0x4b4,
>> +       },
>> +       [4] = {
>> +               .start = 0x560,
>> +               .end = 0x564,
>> +       },
>> +       [5] = {
>> +               .start = 0x600,
>> +               .end = 0x678,
>> +       },
>> +       [6] = {
>> +               .start = 0x694,
>> +               .end = 0x6a0,
>> +       },
>> +       [7] = {
>> +               .start = 0x6b8,
>> +               .end = 0x718,
>> +       },
>> +};
>> +
>> +/* This array lists the valid clocks for each periph clk bank */
>> +static u32 periph_clks_on[] = {
> const?
WIll update in next version of this patch
>> +       0xdcd7dff9,
>> +       0x87d1f3e7,
>> +       0xf3fed3fa,
>> +       0xffc18cfb,
>> +       0x793fb7ff,
>> +       0x3fe66fff,
>> +       0xfc1fc7ff,
> What are these magic numbers?

These are the hard coded values for peripheral clock enable register 
where it enables all clocks before restoring clock sources to proper rate.


>> +};
>> +
>> +static inline unsigned long clk_get_rate_nolock(struct clk *clk)
>> +{
>> +       if (IS_ERR_OR_NULL(clk)) {
> NULL is a valid clk pointer. Typically usage of IS_ERR_OR_NULL() is
> wrong.
>
>> +               WARN_ON(1);
>> +               return 0;
>> +       }
>> +
>> +       return clk_hw_get_rate(__clk_get_hw(clk));
>> +}
>> +
>> +static inline struct clk *pll_p_clk(unsigned int x)
>> +{
>> +       if (x < 4) {
> What is magic value 4?

PLLP outs OUT1 through OUT4 are defined sequential in tegra210-car.h and 
OUT5  is not so retrieving value from clks using sequential indexing for 
up to OUT4.

Will update in next version to use define

>> +               return clks[TEGRA210_CLK_PLL_P_OUT1 + x];
>> +       } else if (x != 4) {
>> +               WARN_ON(1);
>> +               return NULL;
>> +       } else {
>> +               return clks[TEGRA210_CLK_PLL_P_OUT5];
>> +       }
>> +}
>> +
> [..]
>> +
>> +static void tegra210_clk_resume(void)
>> +{
> [..]
>> +       fence_udelay(2, clk_base);
>> +       for (i = 0; i < BURST_POLICY_REG_SIZE; i++) {
>> +               car_writel(cclklp_burst_policy_ctx[i], CCLKLP_BURST_POLICY, i);
>> +               car_writel(sclk_burst_policy_ctx[i], SCLK_BURST_POLICY, i);
>> +       }
>> +       car_writel(sclk_burst_policy_ctx[i], SYS_CLK_DIV, 0);
>> +
>> +       car_writel(sclk_ctx, SYSTEM_CLK_RATE, 0);
>> +       car_writel(spare_ctx, SPARE_REG0, 0);
>> +       car_writel(misc_clk_enb_ctx, MISC_CLK_ENB, 0);
>> +       car_writel(clk_arm_ctx, CLK_MASK_ARM, 0);
>> +
>> +       /* enable all clocks before configuring clock sources */
>> +       tegra_clk_periph_force_on(periph_clks_on, ARRAY_SIZE(periph_clks_on),
>> +                                 clk_base);
>> +
>> +       wmb();
> Please add a comment before barriers so we know what they're for.
Will do in next version of this patch.
>> +       fence_udelay(2, clk_base);
>> +

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