Re: [PATCH] clk: samsung: fsd: Mark PLL_CAM_CSI as critical

Krzysztof Kozlowski
2024-09-19T12:03:14Z

On 19/09/2024 13:33, Inbaraj E wrote:
>
>
>> -----Original Message-----
>> From: Stephen Boyd <sboyd@kernel.org>
>> Sent: 19 September 2024 15:51
>> To: Inbaraj E <inbaraj.e@samsung.com>; alim.akhtar@samsung.com;
>> cw00.choi@samsung.com; krzk@kernel.org; linux-clk@vger.kernel.org; linux-
>> kernel@vger.kernel.org; linux-samsung-soc@vger.kernel.org;
>> mturquette@baylibre.com; s.nawrocki@samsung.com
>> Cc: pankaj.dubey@samsung.com; gost.dev@samsung.com; Inbaraj E
>> <inbaraj.e@samsung.com>
>> Subject: Re: [PATCH] clk: samsung: fsd: Mark PLL_CAM_CSI as critical
>>
>> Quoting Inbaraj E (2024-09-17 03:10:16)
>>> PLL_CAM_CSI is the parent clock for the ACLK and PCLK in the
>>> CMU_CAM_CSI block. When we gate ACLK or PCLK, the clock framework
>> will
>>> subsequently disables the parent clocks(PLL_CAM_CSI). Disabling
>>> PLL_CAM_CSI is causing sytem level halt.
>>>
>>> It was observed on FSD SoC, when we gate the ACLK and PCLK during CSI
>>> stop streaming through pm_runtime_put system is getting halted. So
>>> marking PLL_CAM_CSI as critical to prevent disabling.
>>>
>>> Signed-off-by: Inbaraj E <inbaraj.e@samsung.com>
>>> ---
>>
>> Please add a fixes tag. Although this is likely a band-aid fix because marking
>> something critical leaves it enabled forever.
>
> Sure, will add fixes tag. As per HW manual, this PLL_CAM_CSI is
> supplying clock even for CMU SFR access of CSI block, so we can't
> gate this.

Hm, I am not so sure. The CMU driver should just take appropriate clock.
Sprinkling CLK_CRITICAL looks as substitute of missing clock handling/

Best regards,
Krzysztof