linux-kernel - Re: [PATCH v2 1/4] clk: mediatek: mt8173: Fix enabling of critical clocks

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Date:	Thu, 2 Jul 2015 10:07:42 +0800
From:	Daniel Kurtz <djkurtz@...omium.org>
To:	James Liao <jamesjj.liao@...iatek.com>
Cc:	Matthias Brugger <matthias.bgg@...il.com>,
	Mike Turquette <mturquette@...aro.org>,
	Stephen Boyd <sboyd@...eaurora.org>,
	srv_heupstream <srv_heupstream@...iatek.com>,
	Ricky Liang <jcliang@...omium.org>,
	Rob Herring <robh+dt@...nel.org>,
	Sascha Hauer <kernel@...gutronix.de>,
	"open list:OPEN FIRMWARE AND..." <devicetree@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-mediatek@...ts.infradead.org,
	Sascha Hauer <s.hauer@...gutronix.de>
Subject: Re: [PATCH v2 1/4] clk: mediatek: mt8173: Fix enabling of critical clocks

On Wed, Jul 1, 2015 at 10:21 PM, Daniel Kurtz <djkurtz@...omium.org> wrote:
> Hi James,
>
> To be precise, it is the CLK_TOP clocks that have CLK_APMIXED PLLs as
> their parents, so we cannot enable the CLK_TOP critical clocks until
> the CLK_APMIXED clocks have all been registered.
>
> Please add something like the above to the commit message.
>
> More comments inline...
>
> On Tue, Jun 30, 2015 at 10:58 AM, James Liao <jamesjj.liao@...iatek.com> wrote:
>> From: Sascha Hauer <s.hauer@...gutronix.de>
>>
>> On the MT8173 the clocks are provided by different units. To enable
>> the critical clocks we must be sure that all parent clocks are already
>> registered, otherwise the parents of the critical clocks end up being
>> unused and get disabled later. To find a place where all parents are
>> registered we try each time after we've registered some clocks if
>> all known providers are present now and only then we enable the critical
>> clocks
>>
>> Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
>> Signed-off-by: James Liao <jamesjj.liao@...iatek.com>
>> ---
>>  drivers/clk/mediatek/clk-mt8173.c | 26 +++++++++++++++++++++-----
>>  1 file changed, 21 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/clk/mediatek/clk-mt8173.c b/drivers/clk/mediatek/clk-mt8173.c
>> index 4b9e04c..c483336 100644
>> --- a/drivers/clk/mediatek/clk-mt8173.c
>> +++ b/drivers/clk/mediatek/clk-mt8173.c
>> @@ -700,6 +700,22 @@ static const struct mtk_composite peri_clks[] __initconst = {
>>         MUX(CLK_PERI_UART3_SEL, "uart3_ck_sel", uart_ck_sel_parents, 0x40c, 3, 1),
>>  };
>>
>> +static struct clk_onecell_data *mt8173_top_clk_data;
>> +static struct clk_onecell_data *mt8173_pll_clk_data;
>
> These globals can be:
> __initdata

Oops, never mind about this comment...
Using "__initdata" for uninitialized variables doesn't make sense -
"__initdata" is for initialization data, not variables themselves.

Sorry for the noise,
-Dan

>
>> +
>> +static void mtk_clk_enable_critical(void)
>
> And this function is:
>
> static void __init
>
> Other than the above, this one is:
>
> Reviewed-by: Daniel Kurtz <djkurtz@...omium.org>
>
> -Dan
>
>> +{
>> +       if (!mt8173_top_clk_data || !mt8173_pll_clk_data)
>> +               return;
>> +
>> +       clk_prepare_enable(mt8173_pll_clk_data->clks[CLK_APMIXED_ARMCA15PLL]);
>> +       clk_prepare_enable(mt8173_pll_clk_data->clks[CLK_APMIXED_ARMCA7PLL]);
>> +       clk_prepare_enable(mt8173_top_clk_data->clks[CLK_TOP_MEM_SEL]);
>> +       clk_prepare_enable(mt8173_top_clk_data->clks[CLK_TOP_DDRPHYCFG_SEL]);
>> +       clk_prepare_enable(mt8173_top_clk_data->clks[CLK_TOP_CCI400_SEL]);
>> +       clk_prepare_enable(mt8173_top_clk_data->clks[CLK_TOP_RTC_SEL]);
>> +}
>> +
>>  static void __init mtk_topckgen_init(struct device_node *node)
>>  {
>>         struct clk_onecell_data *clk_data;
>> @@ -712,19 +728,19 @@ static void __init mtk_topckgen_init(struct device_node *node)
>>                 return;
>>         }
>>
>> -       clk_data = mtk_alloc_clk_data(CLK_TOP_NR_CLK);
>> +       mt8173_top_clk_data = clk_data = mtk_alloc_clk_data(CLK_TOP_NR_CLK);
>>
>>         mtk_clk_register_factors(root_clk_alias, ARRAY_SIZE(root_clk_alias), clk_data);
>>         mtk_clk_register_factors(top_divs, ARRAY_SIZE(top_divs), clk_data);
>>         mtk_clk_register_composites(top_muxes, ARRAY_SIZE(top_muxes), base,
>>                         &mt8173_clk_lock, clk_data);
>>
>> -       clk_prepare_enable(clk_data->clks[CLK_TOP_CCI400_SEL]);
>> -
>>         r = of_clk_add_provider(node, of_clk_src_onecell_get, clk_data);
>>         if (r)
>>                 pr_err("%s(): could not register clock provider: %d\n",
>>                         __func__, r);
>> +
>> +       mtk_clk_enable_critical();
>>  }
>>  CLK_OF_DECLARE(mtk_topckgen, "mediatek,mt8173-topckgen", mtk_topckgen_init);
>>
>> @@ -818,13 +834,13 @@ static void __init mtk_apmixedsys_init(struct device_node *node)
>>  {
>>         struct clk_onecell_data *clk_data;
>>
>> -       clk_data = mtk_alloc_clk_data(CLK_APMIXED_NR_CLK);
>> +       mt8173_pll_clk_data = clk_data = mtk_alloc_clk_data(CLK_APMIXED_NR_CLK);
>>         if (!clk_data)
>>                 return;
>>
>>         mtk_clk_register_plls(node, plls, ARRAY_SIZE(plls), clk_data);
>>
>> -       clk_prepare_enable(clk_data->clks[CLK_APMIXED_ARMCA15PLL]);
>> +       mtk_clk_enable_critical();
>>  }
>>  CLK_OF_DECLARE(mtk_apmixedsys, "mediatek,mt8173-apmixedsys",
>>                 mtk_apmixedsys_init);
>> --
>> 1.8.1.1.dirty
>>
--
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