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

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Message-ID: <e2b26bf4-d5ea-4fd8-bcb7-2200aa1bdabc@quicinc.com>
Date: Wed, 25 Sep 2024 11:24:02 +0530
From: Manikanta Mylavarapu <quic_mmanikan@...cinc.com>
To: Bjorn Andersson <quic_bjorande@...cinc.com>
CC: <andi.shyti@...nel.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-i2c@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <quic_srichara@...cinc.com>, <quic_varada@...cinc.com>
Subject: Re: [PATCH 1/1] i2c: qcom-geni: add 32MHz I2C SE clock support for
 IPQ5424



On 9/25/2024 2:15 AM, Bjorn Andersson wrote:
> On Tue, Sep 24, 2024 at 12:20:20PM +0530, Manikanta Mylavarapu wrote:
> 
> Subject gives a clear indication that this is specific to IPQ5424, which
> it isn't. So, please drop that wording from the subject.
> 

Okay, sure.

> Perhaps:
> "i2c: qcom-geni: Support systems with 32MHz SE clock"
> 

Okay, sure.

>> The IPQ5424 I2C SE clock operates at a frequency of 32MHz. Since the
>> existing map table is based on 19.2MHz, this patch incorporate the
>> clock map table to derive the SCL clock from the 32MHz SE clock.
> 
> Then here you're doing the right thing of introducing the IPQ5424, so
> this looks good to me.
> 
>>
>> 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[] = {
>>  	{KHZ(1000), 1, 3,  9, 18},
>>  };
>>  
>> +/* source_clock = 32 MHz */
>> +static const struct geni_i2c_clk_fld geni_i2c_clk_map_32M[] = {
> 
> I'd prefer that you s/32M/32mhz/, and that you rename geni_i2c_clk_map
> to geni_i2c_clk_map_19p2mhz[].
> 

Okay, sure.

>> +	{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;
> 
> Leave itr uninitialized above and add an else here with the assignment,
> to make it clearer that it's one or the other case. (Compared to "It's
> always 19.2MHz and then in some cases we override that with 32MHz")
> 
> 

Okay, sure.

> PS. I wouldn't mind you dropping the addition of the MHZ macro and just
> compare clk_get_rate() with 32000000 and 19200000. But that's a matter
> of taste.
> 

Okay, sure. I will drop MHZ macro.

Thanks & Regards,
Manikanta.

> Regards,
> Bjorn
> 
>> +
>>  	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;
>> -- 
>> 2.34.1
>>