linux-kernel - Re: [PATCH] media: imx-pxp: Rewrite coeff expression

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Message-ID: <CANiDSCvfamZjwOohT8ZFOr-m2SB=r-MCsrXGHtkfEkeYyEo2Nw@mail.gmail.com>
Date: Mon, 15 Jul 2024 10:22:34 +0200
From: Ricardo Ribalda <ribalda@...omium.org>
To: Philipp Zabel <p.zabel@...gutronix.de>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>, Shawn Guo <shawnguo@...nel.org>, 
	Sascha Hauer <s.hauer@...gutronix.de>, Pengutronix Kernel Team <kernel@...gutronix.de>, 
	Fabio Estevam <festevam@...il.com>, linux-media@...r.kernel.org, imx@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	Hans Verkuil <hverkuil-cisco@...all.nl>
Subject: Re: [PATCH] media: imx-pxp: Rewrite coeff expression

Hi Philipp


On Mon, 1 Jul 2024 at 11:30, Philipp Zabel <p.zabel@...gutronix.de> wrote:
>
> On Fr, 2024-06-28 at 15:11 +0000, Ricardo Ribalda wrote:
> > GCC5 cannot figure out that the expressions are constant, and that
> > triggers a build failure. Rewrite the expressions.
> >
> > The following gcc5 error is workaround:
> >
> >  #define BM_PXP_CSC1_COEF0_YCBCR_MODE 0x80000000
> >                                       ^
> >     BM_PXP_CSC1_COEF0_YCBCR_MODE |
> >     ^
> >  #define BM_PXP_CSC1_COEF0_YCBCR_MODE 0x80000000
> >                                       ^
> >
> > drivers/media/platform/nxp/imx-pxp.c: In function 'pxp_setup_csc':
> > drivers/media/platform/nxp/imx-pxp.h:582:38: error: initializer element is not constant
> > drivers/media/platform/nxp/imx-pxp.c:374:4: note: in expansion of macro 'BM_PXP_CSC1_COEF0_YCBCR_MODE'
> > drivers/media/platform/nxp/imx-pxp.h:582:38: note: (near initialization for 'csc1_coef_bt601_lim[0]')
> > Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
>
> Can you elaborate on how this is triggered?

Building the driver with
https://cdn.kernel.org/pub/tools/crosstool/files/bin/x86_64/5.5.0/

It might be easier to repro with:

ribalda@...ia:~/work/linux$ podman run --pids-limit=-1 --rm -it -v
.:/workdir  registry.freedesktop.org/linux-media/media-ci/build-ancient
# cd /workdir
# CROSS_COMPILE=x86_64-linux- make allyesconfig
# scripts/config -d MITIGATION_RETPOLINE
# CROSS_COMPILE=x86_64-linux- make olddefconfig
# CROSS_COMPILE=x86_64-linux- make drivers/media/platform/nxp/


>
> At least I couldn't reproduce this by just copy & pasting the
> csc1_coef_bt601_lim initializer and the required macros into gcc 5.4 on
> godbolt.
>
> Can this be fixed by using GENMASK / FIELD_PREP instead?

I was looking to make the change as simple as possible :)

>
> regards
> Philipp



-- 
Ricardo Ribalda