linux-kernel - Re: [PATCH 4/6] clk: stm32f4: Add I2S clock

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Message-ID: <f219c575-21c2-385f-1aee-7ccc4715028e@st.com>
Date:   Tue, 8 Nov 2016 17:26:57 +0100
From:   Gabriel Fernandez <gabriel.fernandez@...com>
To:     Daniel Thompson <daniel.thompson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Russell King <linux@...linux.org.uk>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Nicolas Pitre <nico@...aro.org>, Arnd Bergmann <arnd@...db.de>,
        <andrea.merello@...il.com>
CC:     <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-clk@...r.kernel.org>,
        <kernel@...inux.com>, <ludovic.barre@...com>,
        <olivier.bideau@...com>, <amelie.delaunay@...com>
Subject: Re: [PATCH 4/6] clk: stm32f4: Add I2S clock



On 11/07/2016 03:14 PM, Daniel Thompson wrote:
> On 07/11/16 13:05, gabriel.fernandez@...com wrote:
>> From: Gabriel Fernandez <gabriel.fernandez@...com>
>>
>> This patch introduces I2S clock for stm32f4 soc.
>> The I2S clock could be derived from an external clock or from pll-i2s
>>
>> Signed-off-by: Gabriel Fernandez <gabriel.fernandez@...com>
>> ---
>>  drivers/clk/clk-stm32f4.c | 12 +++++++++++-
>>  1 file changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/clk/clk-stm32f4.c b/drivers/clk/clk-stm32f4.c
>> index 5fa5d51..b7cb359 100644
>> --- a/drivers/clk/clk-stm32f4.c
>> +++ b/drivers/clk/clk-stm32f4.c
>> @@ -216,6 +216,7 @@ enum {
>>      SYSTICK, FCLK, CLK_LSI, CLK_LSE, CLK_HSE_RTC, CLK_RTC,
>>      PLL_VCO_I2S, PLL_VCO_SAI,
>>      CLK_LCD,
>> +    CLK_I2S,
>
> Sorry, this has just clicked and it applies to most of the other 
> patches, but adding things to this list effectively extends the clock 
> bindings (i.e. the list of valid "other" clocks access with a primary 
> index of 1).
>
> This list if a list of "arbitrary" constants by which DT periphericals 
> can be linked to specific clocks.
>
> So...
>
>  1)  If a clock is introduced here we should update the clock binding
>      documentations.
>
>  2)  If no peripheral can connect to the clock (because it is internal
>      to the clock gen logic and peripherals must connect to the gated
>      version) it should not be included in this enum.
>
>  3)  I failed to mention this when the four undocumented clocks
>      (LSI, LSE, HSE_RTC and RTC) were added.
>
>  4)  I *should* have added a comment explaining the above to the code.
>
>
ok i agree

>>      END_PRIMARY_CLK
>>  };
>>
>> @@ -967,6 +968,8 @@ static struct clk_hw *stm32_register_cclk(struct 
>> device *dev, const char *name,
>>
>>  static const char *sdmux_parents[2] = { "pll48", "sys" };
>>
>> +static const char *i2s_parents[2] = { "plli2s-r", NULL };
>> +
>>  struct stm32f4_clk_data {
>>      const struct stm32f4_gate_data *gates_data;
>>      const u64 *gates_map;
>> @@ -1005,7 +1008,7 @@ struct stm32f4_clk_data {
>>
>>  static void __init stm32f4_rcc_init(struct device_node *np)
>>  {
>> -    const char *hse_clk;
>> +    const char *hse_clk, *i2s_in_clk;
>>      int n;
>>      const struct of_device_id *match;
>>      const struct stm32f4_clk_data *data;
>> @@ -1038,6 +1041,7 @@ static void __init stm32f4_rcc_init(struct 
>> device_node *np)
>>      stm32f4_gate_map = data->gates_map;
>>
>>      hse_clk = of_clk_get_parent_name(np, 0);
>> +    i2s_in_clk = of_clk_get_parent_name(np, 1);
>
> Again this looks like a change to the DT bindings.
>
ok

> Also does the code work if i2s_in_clk is NULL or as you hoping to get 
> away with a not-backwards compatible change?
>
>
yes it works if i2s_in_clk is NULL.

BR
Gabriel

> Daniel.
>
>
>>
>>      clk_register_fixed_rate_with_accuracy(NULL, "hsi", NULL, 0,
>>              16000000, 160000);
>> @@ -1053,6 +1057,12 @@ static void __init stm32f4_rcc_init(struct 
>> device_node *np)
>>      clks[PLL_VCO_SAI] = stm32f4_rcc_register_pll(pllsrc,
>>              &data->pll_data[2], &stm32f4_clk_lock);
>>
>> +    i2s_parents[1] = i2s_in_clk;
>> +
>> +    clks[CLK_I2S] =    clk_hw_register_mux_table(NULL, "i2s",
>> +                i2s_parents, ARRAY_SIZE(i2s_parents), 0,
>> +                base + STM32F4_RCC_CFGR, 23, 1, 0, NULL,
>> +                &stm32f4_clk_lock);
>>      sys_parents[1] = hse_clk;
>>      clk_register_mux_table(
>>          NULL, "sys", sys_parents, ARRAY_SIZE(sys_parents), 0,
>>
>