From: "elaine.zhang" <zhangqing@rock-chips.com>
To: Doug Anderson <dianders@chromium.org>
Cc: Heiko Stuebner <heiko@sntech.de>,
Michael Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@kernel.org>,
Caesar Wang <caesar.wang@rock-chips.com>,
"open list:ARM/Rockchip SoC..."
<linux-rockchip@lists.infradead.org>,
Matthias Kaehlcke <mka@chromium.org>,
Ryan Case <ryandcase@chromium.org>,
linux-clk <linux-clk@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 2/3] clk: rockchip: Make rkpwm a critical clock on rk3288
Date: Thu, 11 Apr 2019 11:42:49 +0800 [thread overview]
Message-ID: <43b5ef8c-4617-bdc5-7109-35eac228b8f9@rock-chips.com> (raw)
In-Reply-To: <CAD=FV=Vyy4bNJV=t2yALP3dAnm0-QsR55F5B==uUoi-Tp6b7Vg@mail.gmail.com>
hi,
在 2019/4/10 下午11:25, Doug Anderson 写道:
> Hi,
>
> On Tue, Apr 9, 2019 at 11:42 PM elaine.zhang <zhangqing@rock-chips.com> wrote:
>> hi,
>>
>> 在 2019/4/10 上午4:47, Douglas Anderson 写道:
>>> Most rk3288-based boards are derived from the EVB and thus use a PWM
>>> regulator for the logic rail. However, most rk3288-based boards don't
>>> specify the PWM regulator in their device tree. We'll deal with that
>>> by making it critical.
>>>
>>> NOTE: it's important to make it critical and not just IGNORE_UNUSED
>>> because all PWMs in the system share the same clock. We don't want
>>> another PWM user to turn the clock on and off and kill the logic rail.
>>>
>>> This change is in preparation for actually having the PWMs in the
>>> rk3288 device tree actually point to the proper PWM clock. Up until
>>> now they've all pointed to the clock for the old IP block and they've
>>> all worked due to the fact that rkpwm was IGNORE_UNUSED and that the
>>> clock rates for both clocks were the same.
>>>
>>> Signed-off-by: Douglas Anderson <dianders@chromium.org>
>>> ---
>>>
>>> drivers/clk/rockchip/clk-rk3288.c | 3 ++-
>>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/clk/rockchip/clk-rk3288.c b/drivers/clk/rockchip/clk-rk3288.c
>>> index 06287810474e..c3321eade23e 100644
>>> --- a/drivers/clk/rockchip/clk-rk3288.c
>>> +++ b/drivers/clk/rockchip/clk-rk3288.c
>>> @@ -697,7 +697,7 @@ static struct rockchip_clk_branch rk3288_clk_branches[] __initdata = {
>>> GATE(PCLK_TZPC, "pclk_tzpc", "pclk_cpu", 0, RK3288_CLKGATE_CON(11), 3, GFLAGS),
>>> GATE(PCLK_UART2, "pclk_uart2", "pclk_cpu", 0, RK3288_CLKGATE_CON(11), 9, GFLAGS),
>>> GATE(PCLK_EFUSE256, "pclk_efuse_256", "pclk_cpu", 0, RK3288_CLKGATE_CON(11), 10, GFLAGS),
>>> - GATE(PCLK_RKPWM, "pclk_rkpwm", "pclk_cpu", CLK_IGNORE_UNUSED, RK3288_CLKGATE_CON(11), 11, GFLAGS),
>>> + GATE(PCLK_RKPWM, "pclk_rkpwm", "pclk_cpu", 0, RK3288_CLKGATE_CON(11), 11, GFLAGS),
>>>
>>> /* ddrctrl [DDR Controller PHY clock] gates */
>>> GATE(0, "nclk_ddrupctl0", "ddrphy", CLK_IGNORE_UNUSED, RK3288_CLKGATE_CON(11), 4, GFLAGS),
>>> @@ -837,6 +837,7 @@ static const char *const rk3288_critical_clocks[] __initconst = {
>>> "pclk_alive_niu",
>>> "pclk_pd_pmu",
>>> "pclk_pmu_niu",
>>> + "pclk_rkpwm",
>> pwm have device node, can enable and disable it in the pwm drivers.
>>
>> pwm regulator use pwm node as:
>>
>> pwms = <&pwm2 0 25000 1>
>>
>> when set Logic voltage:
>>
>> pwm_regulator_set_voltage()
>>
>> --> pwm_apply_state()
>>
>> -->clk_enable()
>>
>> -->pwm_enable()
>>
>> -->pwm_config()
>>
>> -->pinctrl_select()
>>
>> --....
>>
>> For mark pclk_rkpwm as critical,do you have any questions, or provides
>> some log or more information.
> Right, if we actually specify the PWM used for the PWM regulator in
> the device tree then there is no need to mark it as a critical clock.
> In fact rk3288-veyron devices boot absolutely fine without marking
> this clock as critical. Actually, it seems like the way the PWM
> framework works (IIRC it was designed this way specifically to support
> PWM regulators) is that even just specifying that pwm1 is "okay" is
> enough to keep the clock on even if the PWM regulator isn't specified.
>
> ...however...
>
> Take a look at, for instance, the rk3288-evb device tree file.
> Nowhere in there does it specify that the PWM used for the PWM
> regulator should be on. Presumably that means that if we don't mark
> the clock as critical then rk3288-evb will fail to boot. That's easy
> for me to fix since I have the rk3288-evb schematics, but what about
> other rk3288 boards? We could make educated guesses about each of
> them and/or fix things are we hear about breakages.
>
> ...but...
>
> All the above would only be worth doing if we thought someone would
> get some benefit out of it. I'd bet that pretty much all rk3288-based
> boards use a PWM regulator. Thus, in reality, everyone will want the
> rkpwm clock on all the time anyway. In that case going through all
> that extra work / potentially breaking other boards doesn't seem worth
> it. Just mark the clock as critical.
I have no problem with changing it like this, but I think it is better
to modify dts:
vdd_log: vdd-log {
compatible = "pwm-regulator";
rockchip,pwm_id = <2>; //for rk uboot
rockchip,pwm_voltage = <900000>; // for rk uboot
pwms = <&pwm2 0 25000 1>;
regulator-name = "vdd_log";
regulator-min-microvolt = <800000>;//hw logic min voltage
regulator-max-microvolt = <1400000>;//hw logic max voltage
regulator-always-on;
regulator-boot-on;
};
Maybe we did not push the modification of this part in rk3288-evb, I
will push to deal with this.(rk3229-evb.dts and rk3399 has been already
pushed)
>
>
>
>
> -Doug
>
>
>
next prev parent reply other threads:[~2019-04-11 3:42 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-09 20:47 [PATCH 0/3] rockchip: A few clock cleanups for rk3288 Douglas Anderson
2019-04-09 20:47 ` [PATCH 1/3] Revert "clk: rockchip: mark noc and some special clk as critical on rk3288" Douglas Anderson
2019-04-10 6:23 ` elaine.zhang
2019-04-10 15:34 ` Doug Anderson
[not found] ` <1491b5f1-e9f9-5718-76e5-0a49814ed76d@rock-chips.com>
2019-04-11 15:26 ` Doug Anderson
2019-04-11 22:05 ` Heiko Stübner
2019-04-12 1:43 ` elaine.zhang
2019-04-12 15:41 ` Doug Anderson
2019-04-09 20:47 ` [PATCH 2/3] clk: rockchip: Make rkpwm a critical clock on rk3288 Douglas Anderson
2019-04-10 6:42 ` elaine.zhang
2019-04-10 15:25 ` Doug Anderson
2019-04-11 3:42 ` elaine.zhang [this message]
2019-04-11 14:42 ` Doug Anderson
2019-04-11 19:20 ` Heiko Stübner
2019-04-11 19:27 ` Heiko Stübner
2019-04-09 20:47 ` [PATCH 3/3] ARM: dts: rockchip: fix PWM clock found on RK3288 Socs Douglas Anderson
2019-04-11 19:29 ` Heiko Stübner
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