Date:   Tue, 12 Feb 2019 15:04:08 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Lukasz Luba <l.luba@...tner.samsung.com>, cwchoi00@...il.com
Cc:     devicetree <devicetree@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Linux PM list <linux-pm@...r.kernel.org>,
        linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Kukjin Kim <kgene@...nel.org>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, linux-clk@...r.kernel.org,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v4 2/8] clk: samsung: add new clocks for DMC for
 Exynos5422 SoC

Hi Lukasz,

On 19. 2. 11. 오후 8:11, Lukasz Luba wrote:
> Hi Chanwoo,
> 
> On 2/3/19 10:56 AM, Chanwoo Choi wrote:
>> Hi Lukasz,
>>
>> I recommend that please don't send the version up patchset before
>> finishing the discussion.
>>
>> 2019년 2월 2일 (토) 오전 2:47, Lukasz Luba <l.luba@...tner.samsung.com>님이 작성:
>>>
>>> This patch provides support for clocks needed for Dynamic Memory Controller
>>> in Exynos5422 SoC. It adds CDREX base register addresses, new DIV, MUX and
>>> GATE entries.
>>>
>>> Signed-off-by: Lukasz Luba <l.luba@...tner.samsung.com>
>>> ---
>>>   drivers/clk/samsung/clk-exynos5420.c | 46 ++++++++++++++++++++++++++++++++----
>>>   1 file changed, 42 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/clk/samsung/clk-exynos5420.c b/drivers/clk/samsung/clk-exynos5420.c
>>> index 34cce3c..f1a4f56 100644
>>> --- a/drivers/clk/samsung/clk-exynos5420.c
>>> +++ b/drivers/clk/samsung/clk-exynos5420.c
>>> @@ -132,6 +132,8 @@
>>>   #define BPLL_LOCK              0x20010
>>>   #define BPLL_CON0              0x20110
>>>   #define SRC_CDREX              0x20200
>>> +#define GATE_BUS_CDREX0                0x20700
>>> +#define GATE_BUS_CDREX1                0x20704
>>>   #define DIV_CDREX0             0x20500
>>>   #define DIV_CDREX1             0x20504
>>>   #define KPLL_LOCK              0x28000
>>> @@ -248,6 +250,8 @@ static const unsigned long exynos5x_clk_regs[] __initconst = {
>>>          DIV_CDREX1,
>>>          SRC_KFC,
>>>          DIV_KFC0,
>>> +       GATE_BUS_CDREX0,
>>> +       GATE_BUS_CDREX1,
>>>   };
>>>
>>>   static const unsigned long exynos5800_clk_regs[] __initconst = {
>>> @@ -425,6 +429,10 @@ PNAME(mout_group13_5800_p) = { "dout_osc_div", "mout_sw_aclkfl1_550_cam" };
>>>   PNAME(mout_group14_5800_p)     = { "dout_aclk550_cam", "dout_sclk_sw" };
>>>   PNAME(mout_group15_5800_p)     = { "dout_osc_div", "mout_sw_aclk550_cam" };
>>>   PNAME(mout_group16_5800_p)     = { "dout_osc_div", "mout_mau_epll_clk" };
>>> +PNAME(mout_mx_mspll_ccore_phy_p) = { "sclk_bpll", "mout_sclk_dpll",
>>> +                                       "mout_sclk_mpll", "ff_dout_spll2",
>>> +                                       "mout_sclk_spll", "mout_sclk_epll"};
>>> +
>>
>> Remove unneeded extra blank line.
> OK
>>
>>>
>>>   /* fixed rate clocks generated outside the soc */
>>>   static struct samsung_fixed_rate_clock
>>> @@ -450,7 +458,7 @@ static const struct samsung_fixed_factor_clock
>>>   static const struct samsung_fixed_factor_clock
>>>                  exynos5800_fixed_factor_clks[] __initconst = {
>>>          FFACTOR(0, "ff_dout_epll2", "mout_sclk_epll", 1, 2, 0),
>>> -       FFACTOR(0, "ff_dout_spll2", "mout_sclk_spll", 1, 2, 0),
>>> +       FFACTOR(CLK_FF_DOUT_SPLL2, "ff_dout_spll2", "mout_sclk_spll", 1, 2, 0),
>>>   };
>>>
>>>   static const struct samsung_mux_clock exynos5800_mux_clks[] __initconst = {
>>> @@ -472,11 +480,14 @@ static const struct samsung_mux_clock exynos5800_mux_clks[] __initconst = {
>>>          MUX(0, "mout_aclk300_disp1", mout_group5_5800_p, SRC_TOP2, 24, 2),
>>>          MUX(0, "mout_aclk300_gscl", mout_group5_5800_p, SRC_TOP2, 28, 2),
>>>
>>> +       MUX(CLK_MOUT_MX_MSPLL_CCORE_PHY, "mout_mx_mspll_ccore_phy",
>>> +               mout_mx_mspll_ccore_phy_p, SRC_TOP7, 0, 3),
>>> +
>>>          MUX(CLK_MOUT_MX_MSPLL_CCORE, "mout_mx_mspll_ccore",
>>> -                       mout_mx_mspll_ccore_p, SRC_TOP7, 16, 2),
>>> +                       mout_mx_mspll_ccore_p, SRC_TOP7, 16, 3),
>>>          MUX_F(CLK_MOUT_MAU_EPLL, "mout_mau_epll_clk", mout_mau_epll_clk_5800_p,
>>>                          SRC_TOP7, 20, 2, CLK_SET_RATE_PARENT, 0),
>>> -       MUX(0, "sclk_bpll", mout_bpll_p, SRC_TOP7, 24, 1),
>>> +       MUX(CLK_SCLK_BPLL, "sclk_bpll", mout_bpll_p, SRC_TOP7, 24, 1),
>>>          MUX(0, "mout_epll2", mout_epll2_5800_p, SRC_TOP7, 28, 1),
>>>
>>>          MUX(0, "mout_aclk550_cam", mout_group3_5800_p, SRC_TOP8, 16, 3),
>>> @@ -648,7 +659,7 @@ static const struct samsung_mux_clock exynos5x_mux_clks[] __initconst = {
>>
>> The newly added clocks by this patch are supported on all Exynos5420/5422/5800?
> The clocks are the same for Exynos5420/5422/5800 DMCs.
> 
>> I'm not sure because on the patch description, you only mentioned the
>> Exynos5422 without Exynos5420/Exynos5800.
> The driver code supports currently only Exynos5422 due to specific
> timings inside, but the clocks are for all three Exynos SoCs.
> It does not harm the Exynos5420/5800.
>>
>> As for now, I can't check the Exynos TRM because I'm in holiday until
>> next Wednesday. I will check them with Exynos542-/5422/5800 TRM on
>> next Thursday.
> OK, please add me to the communication thread with them. We will speed
> up the process (I can test something for them if needed).
>>
>>>
>>>          MUX(0, "mout_sclk_mpll", mout_mpll_p, SRC_TOP6, 0, 1),
>>>          MUX(CLK_MOUT_VPLL, "mout_sclk_vpll", mout_vpll_p, SRC_TOP6, 4, 1),
>>> -       MUX(0, "mout_sclk_spll", mout_spll_p, SRC_TOP6, 8, 1),
>>> +       MUX(CLK_MOUT_SCLK_SPLL, "mout_sclk_spll", mout_spll_p, SRC_TOP6, 8, 1),
>>>          MUX(0, "mout_sclk_ipll", mout_ipll_p, SRC_TOP6, 12, 1),
>>>          MUX(0, "mout_sclk_rpll", mout_rpll_p, SRC_TOP6, 16, 1),
>>>          MUX_F(CLK_MOUT_EPLL, "mout_sclk_epll", mout_epll_p, SRC_TOP6, 20, 1,
>>> @@ -817,6 +828,8 @@ static const struct samsung_div_clock exynos5x_div_clks[] __initconst = {
>>>          DIV(CLK_DOUT_CLK2X_PHY0, "dout_clk2x_phy0", "dout_sclk_cdrex",
>>>                          DIV_CDREX0, 3, 5),
>>>
>>> +       DIV(0, "dout_pclk_drex0", "dout_cclk_drex0", DIV_CDREX0, 28, 3),
>>
>> Before applied this patch, on line 809, DIV_CDREX0[28:30] was already
>> defined with "dout_pclk_cdrex" gate clock name.
> In my previous email, I have mentioned that the same bits
> (8 combinations) are controlling 3 dividers, which re-branch to 3 edges
> in the clock tree named:
> CLKDIV_PCLK_CDREX, CLKDIV_PCLK_DREX0, CLKDIV_PCLK_DREX1.
> It is in the Exynos5422_UM_REV0.10 documentation section:
> 7.9.6.7 CLK_DIV_CDREX0

It is my missing point. I checked it on Exynos5422 TRM.
I want to develop the clocks according to H/W clock.
Please keep it without removal.

Instead,
It is very strange case. So, you need to add
the detailed comment when defining the multiple clocks
with same register/same bits. Also, in order to reduce
the confusion of this strange case, IMO you better to
define the three clocks at the nearby in this driver.
(CLKDIV_PCLK_CDREX, CLKDIV_PCLK_DREX0, CLKDIV_PCLK_DREX1)
If they are scattered, it is difficult for understanding
why they are developed like this.

> 
> They are put into one because there is a need of synchronization between
> the BUS and DREXs (two external memory interfaces).
> That's why it looks good in the clock information summary when an
> SW engineer can see these HW assumptions.
> 
> If you disagree and would like to see only minimal clock definition
> which makes the HW working, please write it on LKML.
> The clock summary would not be reflecting the actual hierarchy and
> someone who is looking for a specific clock details will not find it.
> 
>   Why do you redefine it
>> with same register/same bit with the different clock name?
> The clock is added for information purpose. I can remove it if you like,
> but then the clock summary would not reflect the actual HW implementation.
> 
>> driver have to get only unique clock for the same register/same bit
>> information.
> True, driver gets the clocks which have exported IDs.
> This one has '0' as you can see and is only for the clk_summary
> information output.
> 
> 
> The purpose of the patch with detailed clock tree related to DMC was
> information, not the driver usage. That's why some clocks they did
> no have IDs so drivers would not take them (without a hack).
> 
>>
>>     808         /* CDREX Block */
>>     809         DIV(CLK_DOUT_PCLK_CDREX, "dout_pclk_cdrex",
>> "dout_aclk_cdrex1",
>>     810                         DIV_CDREX0, 28, 3),
>>
>> And also, you don't use "dout_pclk_drex0" defined by you for
>> CLK_ACLK_PPMU_DREX* gate clock on below. Instead, you use the already
>> defined 'dout_pclk_cdrex' as I commented.
> True
>>
>>> +
>>>          DIV(CLK_DOUT_PCLK_CORE_MEM, "dout_pclk_core_mem", "mout_mclk_cdrex",
>>>                          DIV_CDREX1, 8, 3),
>>>
>>> @@ -1170,6 +1183,31 @@ static const struct samsung_gate_clock exynos5x_gate_clks[] __initconst = {
>>>                          GATE_TOP_SCLK_ISP, 12, CLK_SET_RATE_PARENT, 0),
>>>
>>>          GATE(CLK_G3D, "g3d", "mout_user_aclk_g3d", GATE_IP_G3D, 9, 0, 0),
>>> +
>>
>> Add the following comment for the readability in order to sustain the
>> consistency of this driver.
>> /* CDREX Block */ or /* CDREX */
> OK
>>
>>> +       GATE(CLK_CLKM_PHY0, "clkm_phy0", "dout_sclk_cdrex",
>>> +                       GATE_BUS_CDREX0, 0, 0, 0),
>>> +       GATE(CLK_CLKM_PHY1, "clkm_phy1", "dout_sclk_cdrex",
>>> +                       GATE_BUS_CDREX0, 1, 0, 0),
>>> +       GATE(0, "mx_mspll_ccore_phy", "mout_mx_mspll_ccore_phy",
>>> +                       SRC_MASK_TOP7, 0, CLK_IGNORE_UNUSED, 0),
>>> +
>>> +       GATE(CLK_ACLK_PPMU_DREX0_0, "aclk_ppmu_drex0_0", "dout_aclk_cdrex1",
>>> +                       GATE_BUS_CDREX1, 15, CLK_IGNORE_UNUSED, 0),
>>> +       GATE(CLK_ACLK_PPMU_DREX0_1, "aclk_ppmu_drex0_1", "dout_aclk_cdrex1",
>>> +                       GATE_BUS_CDREX1, 14, CLK_IGNORE_UNUSED, 0),
>>> +       GATE(CLK_ACLK_PPMU_DREX1_0, "aclk_ppmu_drex1_0", "dout_aclk_cdrex1",
>>> +                       GATE_BUS_CDREX1, 13, CLK_IGNORE_UNUSED, 0),
>>> +       GATE(CLK_ACLK_PPMU_DREX1_1, "aclk_ppmu_drex1_1", "dout_aclk_cdrex1",
>>> +                       GATE_BUS_CDREX1, 12, CLK_IGNORE_UNUSED, 0),
>>
>> You better to move the gate clock of GATE_BUS_CDREX[15:12] under the
>> gate clock of GATE_BUS_CDREX[29:26]
>> for the decending order because you defined them as the decending order.
> Make sense, I will change it.
> 
> Regards,
> Lukasz
>>
>>> +
>>> +       GATE(CLK_PCLK_PPMU_DREX0_0, "pclk_ppmu_drex0_0", "dout_pclk_cdrex",
>>> +                       GATE_BUS_CDREX1, 29, CLK_IGNORE_UNUSED, 0),
>>> +       GATE(CLK_PCLK_PPMU_DREX0_1, "pclk_ppmu_drex0_1", "dout_pclk_cdrex",
>>> +                       GATE_BUS_CDREX1, 28, CLK_IGNORE_UNUSED, 0),
>>> +       GATE(CLK_PCLK_PPMU_DREX1_0, "pclk_ppmu_drex1_0", "dout_pclk_cdrex",
>>> +                       GATE_BUS_CDREX1, 27, CLK_IGNORE_UNUSED, 0),
>>> +       GATE(CLK_PCLK_PPMU_DREX1_1, "pclk_ppmu_drex1_1", "dout_pclk_cdrex",
>>> +                       GATE_BUS_CDREX1, 26, CLK_IGNORE_UNUSED, 0),
>>>   };
>>>
>>>   static const struct samsung_div_clock exynos5x_disp_div_clks[] __initconst = {
>>> --
>>> 2.7.4
>>>
>>
>>
>> --
>> Best Regards,
>> Chanwoo Choi
>>
>>
> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

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