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

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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

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)




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