Re: [PATCH v2] media: i2c: ov5640: Implement get_mbus_config

From: Aishwarya Kothari <aishwaryakothari75@gmail.com>
To: Francesco Dolcini <francesco@dolcini.it>,
	Jacopo Mondi <jacopo.mondi@ideasonboard.com>,
	Aishwarya Kothari <aishwarya.kothari@toradex.com>
Cc: Sakari Ailus <sakari.ailus@iki.fi>,
	Marcel Ziswiler <marcel@ziswiler.com>,
	linux-media@vger.kernel.org,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	kernel@pengutronix.de,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	Francesco Dolcini <francesco.dolcini@toradex.com>,
	Marcel Ziswiler <marcel.ziswiler@toradex.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Steve Longerbeam <slongerbeam@gmail.com>,
	linux-kernel@vger.kernel.org,
	Marco Felsch <m.felsch@pengutronix.de>
Subject: Re: [PATCH v2] media: i2c: ov5640: Implement get_mbus_config
Date: Wed, 22 Mar 2023 14:53:32 +0100	[thread overview]
Message-ID: <a1969260-5033-3765-bd94-76cb40dd1729@gmail.com> (raw)
In-Reply-To: <ZBg/4gkKWBMtw5a9@francesco-nb.int.toradex.com>

On 20.03.23 12:13, Francesco Dolcini wrote:
> On Mon, Mar 20, 2023 at 09:48:44AM +0100, Jacopo Mondi wrote:
>> On Tue, Mar 14, 2023 at 01:59:06PM +0100, Francesco Dolcini wrote:
>>> On Tue, Mar 14, 2023 at 02:45:53PM +0200, Sakari Ailus wrote:
>>>> On Tue, Mar 14, 2023 at 01:32:16PM +0100, Francesco Dolcini wrote:
>>>>> On Tue, Mar 14, 2023 at 02:13:46PM +0200, Sakari Ailus wrote:
>>>>>> On Mon, Mar 06, 2023 at 07:36:49AM +0100, Marcel Ziswiler wrote:
>>>>>>> From: Aishwarya Kothari <aishwarya.kothari@toradex.com>
>>>>>>>
>>>>>>> Implement the introduced get_mbus_config operation to report the
>>>>>>> config of the MIPI CSI-2, BT.656 and Parallel interface.
>>>>>>>
>>>>>>> Signed-off-by: Aishwarya Kothari <aishwarya.kothari@toradex.com>
>>>>>>> Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
>>>>>>
>>>>>> What's the reasoning for this patch?
>>>>>
>>>>> Without this it's not possible to use it on i.MX6,
>>>>> drivers/staging/media/imx/imx6-mipi-csi2.c requires it, some more
>>>>> details from Jacopo here [0].
>>>>>
>>>>> Everything used to work fine up to v5.18, after that kernel version
>>>>> various changes broke it [1][2] (I assume you are pretty much aware of
>>>>> the history here, you commented on a few emails).
>>>>>
>>>>> [0] https://lore.kernel.org/all/20230128100611.7ulsfqqqgscg54gy@uno.localdomain/
>>>>> [1] https://lore.kernel.org/all/081cc2d3-1f3a-6c14-6dc7-53f976be7b2b@gmail.com/
>>>>> [2] https://lore.kernel.org/all/cacfe146-101b-35b3-5f66-1a1cabfd342f@gmail.com/
>>>>>
>>>>>> Drivers that don't have e.g. dynamic lane configuration shouldn't need to
>>>>>> implement get_mbus_config.
>>>>
>>>> Not even for staging drivers. The driver should be fixed to get that
>>>> information from the endpoint instead.
>>>
>>> This seems exactly the opposite of what commit
>>> 7318abface48 ("media: imx: Use get_mbus_config instead of parsing upstream DT endpoints")
>>> did.
>>>
>>> Given that I am somehow confused, but I am not that familiar with this
>>> subsystem, so I guess this is expected :-). Can someone provide some
>>> additional hint here?
>>>
>> To be honest my understanding is that this patch has always been
>> needed to work on imx6 and this is not a regression but something that
>> was kept as an out-of-tree patch downstream. Is this correct or is
>> this a regression ?
> 
> I confirm that v5.18 was/is fine.  Aishwarya: correct? In the end you
> tested it, not me :-)
> 
> Francesco
> 
> 
It worked on the v5.18 without this patch.

Aishwarya