linux-kernel - Re: [PATCH 1/1] i2c: qcom-geni: add 32MHz I2C SE clock support for IPQ5424

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Message-ID: <ad86f820-1e9f-4e15-b106-3e2136dbf438@quicinc.com>
Date: Wed, 25 Sep 2024 15:25:12 +0530
From: Mukesh Kumar Savaliya <quic_msavaliy@...cinc.com>
To: Manikanta Mylavarapu <quic_mmanikan@...cinc.com>, <andi.shyti@...nel.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-i2c@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC: <quic_srichara@...cinc.com>, <quic_varada@...cinc.com>
Subject: Re: [PATCH 1/1] i2c: qcom-geni: add 32MHz I2C SE clock support for
 IPQ5424

Thanks manikanta !

On 9/25/2024 2:14 PM, Manikanta Mylavarapu wrote:
> 
> 
> On 9/25/2024 1:06 PM, Mukesh Kumar Savaliya wrote:
>> Hi Manikanta,
>>
>> On 9/24/2024 12:20 PM, Manikanta Mylavarapu wrote:
>>> The IPQ5424 I2C SE clock operates at a frequency of 32MHz. Since the
>> would it be better to say , I2C SE is sourced from 32MHZ ?
> 
> Okay, sure.
> 
>>> existing map table is based on 19.2MHz, this patch incorporate the
>> based on 19.2MHz. this patch /,/.
> 
> Okay, sure.
> 
>>> clock map table to derive the SCL clock from the 32MHz SE clock.
>> from the 32MHz Source Clock frequency.
>> SE = Expand OR  (I2C Serial Engine Controller)
> 
> Okay, sure.
> 
Please also mention the reason why 32MHz got added ? Need to describe 
evolution to understand the purpose behind this change.
>>>
>>> Signed-off-by: Manikanta Mylavarapu <quic_mmanikan@...cinc.com>
>>> ---
>>>    drivers/i2c/busses/i2c-qcom-geni.c | 11 +++++++++++
>>>    1 file changed, 11 insertions(+)
>>>
>>> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
>>> index 212336f724a6..bbd9ecf09f4b 100644
>>> --- a/drivers/i2c/busses/i2c-qcom-geni.c
>>> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
>>> @@ -71,6 +71,7 @@ enum geni_i2c_err_code {
>>>      #define I2C_AUTO_SUSPEND_DELAY    250
>>>    #define KHZ(freq)        (1000 * freq)
>>> +#define MHZ(freq)        (1000000 * freq)
>>>    #define PACKING_BYTES_PW    4
>>>      #define ABORT_TIMEOUT        HZ
>>> @@ -152,11 +153,21 @@ static const struct geni_i2c_clk_fld geni_i2c_clk_map[] = {
>> A thought - Should we rename this appending _19.2M ? In future one or more may come as it evolves speed.
> 
> Okay, sure.
> 
> Thanks & Regards,
> Manikanta.
> 
>>>        {KHZ(1000), 1, 3,  9, 18},
>>>    };
>>>    +/* source_clock = 32 MHz */
>>> +static const struct geni_i2c_clk_fld geni_i2c_clk_map_32M[] = {
>>> +    {KHZ(100), 7, 14, 18, 40},
>>> +    {KHZ(400), 4,  3, 11, 20},
>>> +    {KHZ(1000), 4, 3,  6, 15},
>>> +};
>>> +
>>>    static int geni_i2c_clk_map_idx(struct geni_i2c_dev *gi2c)
>>>    {
>>>        int i;
>>>        const struct geni_i2c_clk_fld *itr = geni_i2c_clk_map;
>>>    +    if (clk_get_rate(gi2c->se.clk) == MHZ(32))
>>> +        itr = geni_i2c_clk_map_32M;
>>> +
>>>        for (i = 0; i < ARRAY_SIZE(geni_i2c_clk_map); i++, itr++) {
>>>            if (itr->clk_freq_out == gi2c->clk_freq_out) {
>>>                gi2c->clk_fld = itr;
>