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.k...@canonical.com>

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.k...@canonical.com>
---
  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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