linux-kernel - Re: [PATCH] clk: qcom: gcc: Update the SDCC clock to use shared_floor

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Message-ID: <d0871d6d-7593-4cbc-b5dd-2ec358bda27a@oss.qualcomm.com>
Date: Thu, 7 Aug 2025 19:02:58 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Taniya Das <taniya.das@....qualcomm.com>,
        Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Bjorn Andersson <andersson@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd
 <sboyd@...nel.org>, Dmitry Baryshkov <lumag@...nel.org>,
        Taniya Das <quic_tdas@...cinc.com>,
        Ajit Pandey <quic_ajipan@...cinc.com>,
        Imran Shaik <quic_imrashai@...cinc.com>,
        Jagadeesh Kona <quic_jkona@...cinc.com>, linux-arm-msm@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: qcom: gcc: Update the SDCC clock to use
 shared_floor_ops

On 8/6/25 11:39 AM, Taniya Das wrote:
> 
> 
> On 8/6/2025 3:00 PM, Konrad Dybcio wrote:
>> On 8/6/25 11:27 AM, Taniya Das wrote:
>>>
>>>
>>> On 8/5/2025 10:52 AM, Dmitry Baryshkov wrote:
>>>> On Mon, Aug 04, 2025 at 11:59:21PM +0530, Taniya Das wrote:
>>>>> gcc_sdcc2_apps_clk_src: rcg didn't update its configuration" during
>>>>> boot. This happens due to the floor_ops tries to update the rcg
>>>>> configuration even if the clock is not enabled.
>>>>
>>>> This has been working for other platforms (I see Milos, SAR2130P,
>>>> SM6375, SC8280XP, SM8550, SM8650 using shared ops, all other platforms
>>>> seem to use non-shared ops). What's the difference? Should we switch all
>>>> platforms? Is it related to the hypervisor?
>>>>
>>>
>>> If a set rate is called on a clock before clock enable, the
>>
>> Is this something we should just fix up the drivers not to do?
>>
> 
> I do not think CCF has any such limitation where the clock should be
> enabled and then a clock rate should be invoked. We should handle it
> gracefully and that is what we have now when the caching capabilities
> were added in the code. This has been already in our downstream drivers.

Should we do CFG caching on *all* RCGs to avoid having to scratch our
heads over which ops to use with each clock individually?

> 
> We can add the fix to do a check 'clk_hw_is_enabled(hw)' in the normal
> rcg2_ops/rcg2_floor/ceil_ops as well, then we can use them.

FWIW this is not the first time this issue has popped up..

I don't remember the details other than what I sent in the thread

https://lore.kernel.org/linux-arm-msm/20240427-topic-8450sdc2-v1-1-631cbb59e0e5@linaro.org/

Konrad
> 
> AFAIK the eMMC framework has this code and this is not limited to drivers.
>