Message-ID: <910dbd8f-85f2-4979-49ee-6d760e89af84@ideasonboard.com>
Date:   Fri, 2 Dec 2022 11:57:18 +0800
From:   Umang Jain <umang.jain@...asonboard.com>
To:     Stefan Wahren <stefan.wahren@...e.com>,
        linux-media@...r.kernel.org, kernel-list@...pberrypi.com,
        linux-kernel@...r.kernel.org, linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-staging@...ts.linux.dev,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>
Cc:     Dave Stevenson <dave.stevenson@...pberrypi.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Naushir Patuck <naush@...pberrypi.com>,
        David Plowman <david.plowman@...pberrypi.com>,
        Kieran Bingham <kieran.bingham@...asonboard.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Subject: Re: [PATCH 00/14] staging: vc04_services: bcm2835-isp support

Hi Stefan,

On 12/2/22 6:45 AM, Stefan Wahren wrote:
> Hi Umang,
>
> Am 30.11.22 um 11:58 schrieb Umang Jain:
>> Hi Stefan,
>>
>> On 11/27/22 6:56 AM, Stefan Wahren wrote:
>>> Hi Umang,
>>>
>>> Am 26.11.22 um 17:26 schrieb Umang Jain:
>>>> Hi Stefan
>>>>
>>>> On 11/26/22 8:12 PM, Stefan Wahren wrote:
>>>>> Hi Umang,
>>>>>
>>>>> Am 21.11.22 um 22:47 schrieb Umang Jain:
>>>>>> This series aims to upport bcm2835-isp from the RPi kernel [1] 
>>>>>> and is a
>>>>>> independent subset of earlier series [2] posted to upport CSI-2/CCP2
>>>>>> receiver IP core("Unicam) + the ISP driver found in BCM283x and 
>>>>>> compatible
>>>>>> SoCs (namely BCM2711). Unicam is still under active development 
>>>>>> to work
>>>>>> with multistream support to get into mainline. Hence only the ISP 
>>>>>> driver
>>>>>> will remain the primary area of this series.
>>>>>
>>>>> thanks for working on this. But honestly i would prefer that vchiq 
>>>>> comes out of staging before adding more features. As Greg said 
>>>>> some time ago staging is not a place to "dump code and run away". 
>>>>> These new files are in the same bad shape as the rest of vc04 
>>>>> before the clean-up here in staging started.
>>>>
>>>> Certainly, I am not here to do that - but I am still learning the 
>>>> ropes.
>>> no problem.
>>>>
>>>> If the staging issue is becoming a blocker for bcm2835-isp going 
>>>> upstream, I would be happy to help here! Though I must mention that 
>>>> I still have limited visibility so my aim would be to chart out a 
>>>> plan of things needed to be done to get vc04_services out of staging!
>>>
>>> The vchiq driver is in staging since 2016, so every step forwards is 
>>> good. Unfortunately all of the low hanging fruits has been gathered.
>>>
>>> For me the most important, but not to tricky steps to get vchiq out 
>>> of staging would be:
>>>
>>> * Cleanup logging mechanism
>>>
>>> * Get rid of custom function return values
>>>
>>> There was already an attempt for this [1]
>>>
>>> * Get rid of all non essential global structures and create a proper 
>>> per
>>> device structure
>>>
>>>>
>>>>>
>>>>> I agree that VCSM is on the TODO list for vchiq, but this driver 
>>>>> is not necessary for making bcm2835-audio & bcm2835-camera leave 
>>>>> staging. It just binds more resources on a new feature.
>>
>> bcm2835-camera is the legacy camera stack which probably need to be 
>> dropped from hereon...
> I don't not know if there any users left, so i would be careful here. 
> Can bcm2835-isp completely replace bcm2835-camera? Sorry, for this 
> dumb question but i'm not expert here.

I am careful too here and probably need Input from RaspberryPi in order 
to proceed to drop it. But from my perspective - bcm2835-camera is _not_ 
going out of staging - it'll either sit here (or probably dropped) as 
statied from [1]

```
+ * There are two camera drivers in the kernel for BCM283x - this one
+ * and bcm2835-camera (currently in staging).
```

The bcm2835-camera is meant to be replaced by unicam [1] , but the ISP 
(bcm2835-isp) is meant to be worked with unicam [1]. In fact, I have 
mentioned in my cover the testing of bcm2835-isp happened on top of 
unicam patches.

[1]: 
https://lore.kernel.org/linux-media/20220208155027.891055-5-jeanmichel.hautbois@ideasonboard.com/
>>>>
>>>> I see two TODO files in vc04_services:
>>>>     ./bcm2835-camera/TODO
>>>>     ./interface/TODO
>>>>
>>>> One of the bcm2835-camera TODO points to the vc-sm-cma driver 
>>>> itself. So that's address in the series. The other remaining one - 
>>>> I will need to take a deeper look before commenting on it.
>>>>
>>>> The main chunk of TODO are in vc04_services/interfaces/TODO. Doing 
>>>> a cursory reading of them suggests that these apply to *all* 
>>>> vc04_services components? Am I right?
>>> Actually these applies just for the interfaces directory. Some of 
>>> them could apply to the services, but this is no priority.
>>
>> By no priority, you mean this doesn't affect the criteria required to 
>> ful-fill to get these out of staging?
> Correct
>>>>
>>>> Are these are the specific bits of cleanup you are referring to in 
>>>> your comment?
>>>
>>> You mean about bcm2835-isp? There were too many changes to vchiq 
>>> that i don't remember them all. The first that come to my mind was 
>>> those fancy comment sections which is not kernel coding style. It 
>>> has been removed.
>>
>> No, I don't mean the bcm2835-isp changes (those are upcoming / 
>> out-of-tree still so...). I mean what are the specific bits / points 
>> that needs to be addressed to get vc04_services out of the staging.
> These were the points which i mentioned in my last email. They came 
> from interface/TODO.
>>
>> You have mentioned it above now, so I'll follow up on those.
> That would be great :)
>> The many vchiq changes you referred to above comment (that you don't 
>> remember) are from [1] as well or some other series ?
> Sorry, for the confusing. The many changes i refer were the dozens of 
> clean up patches for vc04_interfaces in mainline staging since the 
> last years. [1] was just a single patch which has been accepted yet.

Ah I see. There are many others that I've to dig out then. Thanks for 
clarifying!
>>
>>>
>>> [1] - 
>>> https://lore.kernel.org/linux-staging/20220712181928.17547-1-jslebodn@redhat.com/
>>>
>>>>
>>>>
>>>>>
>>>>> Unfortuntately i hadn't much time to work on vchiq by myself.
>>>>>
>>>>> Just my two cents
>>>>> Stefan
>>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> linux-arm-kernel mailing list
>>>> linux-arm-kernel@...ts.infradead.org
>>>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>

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