Received-SPF: pass (google.com: domain of linux-kernel+bounces-56097-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161;
Message-ID: <5f54ee18-b3df-4918-9d5e-b765a6714ea2@ti.com>
Date: Wed, 7 Feb 2024 13:36:05 +0530
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH v2] clk: keystone: sci-clk: Adding support for non
 contiguous clocks
Content-Language: en-US
To: "Kumar, Udit" <u-kumar1@ti.com>, Kamlesh Gurudasani <kamlesh@ti.com>,
        Nishanth Menon <nm@ti.com>, <vishalm@ti.com>
CC: <kristo@kernel.org>, <ssantosh@kernel.org>, <rishabh@ti.com>,
        <vigneshr@ti.com>, <mturquette@baylibre.com>, <sboyd@kernel.org>,
        <linux-arm-kernel@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
        <linux-clk@vger.kernel.org>
References: <20240206104357.3803517-1-u-kumar1@ti.com>
 <20240206131420.wtitflgav23jto2q@verbally>
 <871q9pzoiq.fsf@kamlesh.i-did-not-set--mail-host-address--so-tickle-me>
 <c5b6bd1d-dbb4-4bfb-8b3e-9b0733e2ba5d@ti.com>
 <c2b7f22d-f07d-4cac-8a01-af7b014e7ff4@ti.com>
 <a4fdbcfe-e0e0-4280-8638-e39b6b46778e@ti.com>
 <87ttmly4fa.fsf@kamlesh.i-did-not-set--mail-host-address--so-tickle-me>
 <e2ea03ce-0367-413b-aca9-7c1fabda173a@ti.com>
 <4398af20-3396-4a5c-8fcb-a7b3d0d6f15b@ti.com>
 <978c8110-3083-4fc2-a348-d7f97fd7839c@ti.com>
From: CHANDRU DHAVAMANI <chandru@ti.com>
In-Reply-To: <978c8110-3083-4fc2-a348-d7f97fd7839c@ti.com>
Content-Type: text/plain; charset="UTF-8"; format=flowed
Content-Transfer-Encoding: 8bit


On 07/02/24 13:03, Kumar, Udit wrote:
>
> On 2/7/2024 12:53 PM, CHANDRU DHAVAMANI wrote:
>>
>> On 07/02/24 11:03, Kumar, Udit wrote:
>>>
>>> On 2/6/2024 9:24 PM, Kamlesh Gurudasani wrote:
>>>> "Kumar, Udit" <u-kumar1@ti.com> writes:
>>>>
>>>>>>>>> get_freq is a bit expensive as it has to walk the clock tree 
>>>>>>>>> to find
>>>>>>>>> the clock frequency (at least the first time?). just wondering if
>>>>>>>>> there is lighter alternative here?
>>>>>>>>>
>>>>>>>> How about get_clock? Doesn't read the registers at least.
>>>>>>> Said API needs, some flags to be passed,
>>>>>>>
>>>>>>> Can those flag be set to zero, Chandru ?
>>>>>>
>>>>>> get_clock doesn't require any flags to be passed.
>>>>>
>>>>> May be firmware does not need it but  I was referring to
>>>>>
>>>>> https://elixir.bootlin.com/linux/latest/source/drivers/clk/keystone/sci-clk.c#L78 
>>>>>
>>>> Just took a look,
>>>>
>>>> I now understand the reason for confusion,
>>>>
>>>> #define TI_SCI_MSG_SET_CLOCK_STATE    0x0100
>>>> #define TI_SCI_MSG_GET_CLOCK_STATE    0x0101
>>>>
>>>> cops->get_clock = ti_sci_cmd_get_clock;  --> refers to
>>>> TI_SCI_MSG_SET_CLOCK_STATE
>>>> That's why we are passing the flag from linux for get_clock
>>>>
>>>> Linux is using terminology of get/put.
>>>>
>>>> As Chandru pointed, we don't have to pass flags, cause he is refering
>>>> to TI_SCI_MSG_GET_CLOCK_STATE
>>>>
>>>> Below functions passes TI_SCI_MSG_GET_CLOCK_STATE to DM, which is what
>>>> we actually want.
>>>> cops->is_auto = ti_sci_cmd_clk_is_auto;
>>>> cops->is_on = ti_sci_cmd_clk_is_on;
>>>> cops->is_off = ti_sci_cmd_clk_is_off;
>>>
>>>
>>> I think calling ti_sci_cmd_clk_is_auto should be good . other 
>>> functions needs current state and requested state.
>>>
>>> Chandru ?
>>>
>>
>> ti_sci_cmd_clk_is_auto is internal function to linux.
>> For TI_SCI_MSG_GET_CLOCK_STATE, linux only needs to pass pointers to 
>> the variables where result will be stored.
>
>
> Yes this internal function calls TI_SCI_MSG_GET_CLOCK_STATE
>

Okay. We can use TI_SCI_MSG_GET_CLOCK_STATE to check to if clock is 
valid or not.


>
>>
>>
>>>>
>>>> Which should be safe to call, Chandru can confirm.
>>>>
>>>> Regards,
>>>> Kamlesh
>>>>>
>>>>>
>>>>>>
>>>>>>>
>>>>>>>> Regards,
>>>>>>>> Kamlesh