linux-kernel - Re: [PATCH 1/4] media: i2c: imx214: Explain some magic numbers

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Date:   Tue, 24 Oct 2023 09:30:01 +0200
From:   André Apitzsch <git@...tzsch.eu>
To:     Kieran Bingham <kieran.bingham@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Ricardo Ribalda <ribalda@...nel.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        ~postmarketos/upstreaming@...ts.sr.ht
Subject: Re: [PATCH 1/4] media: i2c: imx214: Explain some magic numbers

Am Montag, dem 23.10.2023 um 23:44 +0100 schrieb Kieran Bingham:
> Quoting André Apitzsch (2023-10-23 22:47:50)
> > Code refinement, no functional changes.
> > 
> > Signed-off-by: André Apitzsch <git@...tzsch.eu>
> > ---
> >  drivers/media/i2c/imx214.c | 24 +++++++++++++++++++-----
> >  1 file changed, 19 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/media/i2c/imx214.c
> > b/drivers/media/i2c/imx214.c
> > index 4f77ea02cc27..9218c149d4c8 100644
> > --- a/drivers/media/i2c/imx214.c
> > +++ b/drivers/media/i2c/imx214.c
> > @@ -19,12 +19,23 @@
> >  #include <media/v4l2-fwnode.h>
> >  #include <media/v4l2-subdev.h>
> >  
> > +#define IMX214_REG_MODE_SELECT         0x0100
> > +#define IMX214_MODE_STANDBY            0x00
> > +#define IMX214_MODE_STREAMING          0x01
> > +
> >  #define IMX214_DEFAULT_CLK_FREQ        24000000
> >  #define IMX214_DEFAULT_LINK_FREQ 480000000
> >  #define IMX214_DEFAULT_PIXEL_RATE ((IMX214_DEFAULT_LINK_FREQ *
> > 8LL) / 10)
> >  #define IMX214_FPS 30
> >  #define IMX214_MBUS_CODE MEDIA_BUS_FMT_SRGGB10_1X10
> >  
> > +/* Exposure control */
> > +#define IMX214_REG_EXPOSURE            0x0202
> > +#define IMX214_EXPOSURE_MIN            0
> > +#define IMX214_EXPOSURE_MAX            3184
> > +#define IMX214_EXPOSURE_STEP           1
> > +#define IMX214_EXPOSURE_DEFAULT                0x0c70
> 
> I like this change, and I see that 0x0c70 was directly moved here
> from
> the code below. But could we replace 0xc70 here with 3184 please so
> that
> it's /far/ clearer that the Exposure Default == Exposure Max which is
> otherwise hidden?
> 
Hi Kieran,

I can do that. But I propose to replace 3184 with 0x0c70 instead.
Because that matches the entries used in the reg_8 lists
mode_4096x2304[] and mode_1920x1080[].

	{0x0202, 0x0C},
	{0x0203, 0x70}, 

What do you think?

Regards,
André

> --
> Regards
> 
> Kieran
>