Re: [PATCH] media: staging: rkisp1: rsz: make const array static, makes object smaller

[Dafna Hirschfeld]

Am 20.10.20 um 17:29 schrieb David Laight:
> From: Colin King
> > Sent: 20 October 2020 15:47
> >
> > From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> >
> > Don't populate the const array dev_names on the stack but instead it
> > static. Makes the object code smaller by 15 bytes.
> >
> > Before:
> >     text	   data	    bss	    dec	    hex	filename
> >    17091	   2648	     64	  19803	   4d5b	media/rkisp1/rkisp1-resizer.o
> >
> > After:
> >     text	   data	    bss	    dec	    hex	filename
> >    17012	   2712	     64	  19788	   4d4c	media/rkisp1/rkisp1-resizer.o
> >
> > (gcc version 10.2.0)
> >
> > Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> > ---
> >   drivers/staging/media/rkisp1/rkisp1-resizer.c | 6 ++++--
> >   1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/staging/media/rkisp1/rkisp1-resizer.c b/drivers/staging/media/rkisp1/rkisp1-
> > resizer.c
> > index 1687d82e6c68..7ca5b47c5bf5 100644
> > --- a/drivers/staging/media/rkisp1/rkisp1-resizer.c
> > +++ b/drivers/staging/media/rkisp1/rkisp1-resizer.c
> > @@ -763,8 +763,10 @@ static void rkisp1_rsz_unregister(struct rkisp1_resizer *rsz)
> >
> >   static int rkisp1_rsz_register(struct rkisp1_resizer *rsz)
> >   {
> > -	const char * const dev_names[] = {RKISP1_RSZ_MP_DEV_NAME,
> > -					  RKISP1_RSZ_SP_DEV_NAME};
> > +	static const char * const dev_names[] = {
> > +		RKISP1_RSZ_MP_DEV_NAME,
> > +		RKISP1_RSZ_SP_DEV_NAME
> > +	};
> >   	struct media_pad *pads = rsz->pads;
> >   	struct v4l2_subdev *sd = &rsz->sd;
> >   	int ret;
>
> Don't look at what that code is actually doing....
> It is rather horrid.
> rkisp1_rsz_register() is called for each entry in an array (twice).
> The array index is written into rsz->id.
> The value is then used to select one of the two strings.
> But rsz->id is actually an enum type.

Hi,
Is it that bad to use enum as an array index?
we use it in many places in the driver.

Thanks,
Dafna

> rkisp1_rsz_register() should probably just be called twice with some
> extra parameters.
>
> 	David
>
> -
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