Re: [RFC PATCH 00/14] CAMSS support for MSM8974

From: Brian Masney <bmasney@redhat.com>
To: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Luca Weiss <luca@z3ntu.xyz>,
	linux-arm-msm@vger.kernel.org,
	~postmarketos/upstreaming@lists.sr.ht,
	phone-devel@vger.kernel.org,
	Loic Poulain <loic.poulain@linaro.org>,
	Robert Foss <robert.foss@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Todor Tomov <todor.too@gmail.com>, Andy Gross <agross@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	linux-i2c@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
	matti.lehtimaki@gmail.com
Subject: Re: [RFC PATCH 00/14] CAMSS support for MSM8974
Date: Mon, 23 May 2022 14:30:18 -0400	[thread overview]
Message-ID: <YovSurcGlyPW7v9s@xps13> (raw)
In-Reply-To: <638d6986-616f-4a1c-f1d0-82835b000b2a@linaro.org>

On Mon, May 23, 2022 at 03:39:53PM +0300, Dmitry Baryshkov wrote:
> On 22/05/2022 19:27, Luca Weiss wrote:
> > This RFC series adds support for CAMSS and CCI that are found on
> > msm8974, including the OV8865 found on the FP2.
> > 
> > The only reason it's marked RFC is that CAMSS doesn't behave properly on
> > this SoC without the last commit which is obviously not upstreamable.
> > Not sure if this should be a blocker for including most of the other
> > patches because other than that it seems to work fine and I can get a
> > picture from the camera sensor. When/if msm8974 gets IOMMU support I
> > hope this should be resolved and it works without this hack.
> > 
> > I think at least the CCI patches could get applied as they're not
> > dependent on the CAMSS hack?
> 
> I'd also vote for the camcc patches to be applied.
> 
> As for the camss, I'd suggest to get them verified to work properly with a
> hacked/non-upstreamable/etc. IOMMU driver if one exists. Otherwise we can
> easily get into a situation where we merge up code that contains bugs
> itself.

Last I checked, there's no IOMMU driver for msm8974 that works with an
upstream kernel at the moment. About 2 years ago, I took a stab at
attempting to enable IOMMU for the display and ran into some issues that
I documented at:

https://lore.kernel.org/lkml/20200109002606.35653-1-masneyb@onstation.org/

I'm not familiar with this part of the hardware and haven't had time
since then to look into this further.

Brian