linux-kernel - Re: [PATCH v9 00/28] Qualcomm iris video decoder driver

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Message-ID: <4dab19d0-22eb-2395-56fd-758c3c0d8bc7@quicinc.com>
Date: Mon, 3 Feb 2025 14:57:58 +0530
From: Vikash Garodia <quic_vgarodia@...cinc.com>
To: Johan Hovold <johan@...nel.org>,
        Stefan Schmidt
	<stefan.schmidt@...aro.org>
CC: Dikshita Agarwal <quic_dikshita@...cinc.com>,
        Abhinav Kumar
	<quic_abhinavk@...cinc.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        "Rob
 Herring" <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        "Conor
 Dooley" <conor+dt@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        "Hans
 Verkuil" <hverkuil@...all.nl>,
        Sebastian Fricke
	<sebastian.fricke@...labora.com>,
        Bryan O'Donoghue
	<bryan.odonoghue@...aro.org>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Nicolas Dufresne
	<nicolas@...fresne.ca>,
        Uwe Kleine-König
	<u.kleine-koenig@...libre.com>,
        Jianhua Lu <lujianhua000@...il.com>, <linux-media@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        "Krzysztof
 Kozlowski" <krzysztof.kozlowski@...aro.org>,
        Vedang Nagar
	<quic_vnagar@...cinc.com>,
        Bjorn Andersson <andersson@...nel.org>
Subject: Re: [PATCH v9 00/28] Qualcomm iris video decoder driver


On 2/3/2025 2:13 PM, Johan Hovold wrote:
> On Wed, Jan 22, 2025 at 04:34:51PM +0100, Stefan Schmidt wrote:
>> On Thu, 9 Jan 2025 at 15:58, Johan Hovold <johan@...nel.org> wrote:
>>> On Thu, Dec 12, 2024 at 05:21:22PM +0530, Dikshita Agarwal wrote:
> 
>>>> Introduce support for Qualcomm new video acceleration hardware i.e.
>>>> iris, used for video stream decoding.
>>>
>>>> Note: A harmless onetime error log "Lucid PLL latch failed. Output may
>>>> be unstable!" is seen during bootup.  It doesn't impact any video
>>>> usecase and is currently under discussion.
>>>
>>> This could be an indication that some resources are not described
>>> correctly and could potentially require both binding and driver changes
>>> to address.
>>>
>>> This is also something which could cause trouble later (e.g. during
>>> suspend) even if you manage to get the clock running after boot.
>>>
>>> Generally, you should not be introducing any new warnings; they are
>>> there to let you know that something is wrong.
>>>
>>> Where is this issue being discussed?
>>>
>>> I think we at least need a public analysis and understanding of the
>>> problem before merging this.
>>
>> Taniya Das proposed a patchset to reconfigure PLL in the clk-alpha-pll
>> which allows the videocc-sm8550 driver to configure it correctly.
>> https://lore.kernel.org/linux-arm-msm/20250113-support-pll-reconfigure-v1-0-1fae6bc1062d@quicinc.com/T/
>>
>> I tested the Iris driver with this patchset and I am no longer seeing
>> the Lucid PLL latch failed warning.
> 
> Thanks for the pointer. Please make sure to reference this series (and
> summarise the underlying issue) when resending this series.
> 
> Judging from a quick look the approach taken there seems like a bit of a
> hack so it may not get merged in its current form. IIUC fixing the PLL
> issue properly may depend on adding support for multiple power domains
> to the clock drivers.
It would be good if you can add your comment to the PLL fix series [1] so that
the patch owner can discuss on your suggestion.
Regards,
Vikash

[1]
https://lore.kernel.org/linux-arm-msm/20250113-support-pll-reconfigure-v1-0-1fae6bc1062d@quicinc.com/T/