Re: [Patch 10/13] media: am437x-vpfe: Remove print_fourcc helper

Joe Perches
2019-09-09T16:39:47Z

On Mon, 2019-09-09 at 11:27 -0500, Benoit Parrot wrote:
> print_fourcc helper function was used for debug log the
> convert a pixel format code into its readable form for display
> purposes. But since it used a single static buffer to perform
> the conversion this might lead to display format issue when more
> than one instance was invoked simultaneously.
>
> It turns out that print_fourcc can be safely replace by using
> "%4.4s" instead and casting the pointer to the fourcc code
> into a (char *).
[]
> diff --git a/drivers/media/platform/am437x/am437x-vpfe.c b/drivers/media/platform/am437x/am437x-vpfe.c
[]
> @@ -221,20 +221,6 @@ static void pix_to_mbus(struct vpfe_device *vpfe,
[]
> @@ -700,8 +686,8 @@ static int vpfe_ccdc_set_pixel_format(struct vpfe_ccdc *ccdc, u32 pixfmt)
> {
> struct vpfe_device *vpfe = container_of(ccdc, struct vpfe_device, ccdc);
>
> - vpfe_dbg(1, vpfe, "%s: if_type: %d, pixfmt:%s\n",
> - __func__, ccdc->ccdc_cfg.if_type, print_fourcc(pixfmt));
> + vpfe_dbg(1, vpfe, "%s: if_type: %d, pixfmt:%4.4s\n",
> + __func__, ccdc->ccdc_cfg.if_type, (char *)&pixfmt);

To avoid any possible defect in the content of pixfmt, it's
probably better to use vsprintf extension "%4pE", &pixfmt
see: Documentation/core-api/printk-formats.rst

vpfe_dbg(1, vpfe, "%s: if_type: %d, pixfmt:%4pE\n",
__func__, ccdc->ccdc_cfg.if_type, &pixfmt);

>
> if (ccdc->ccdc_cfg.if_type == VPFE_RAW_BAYER) {
> ccdc->ccdc_cfg.bayer.pix_fmt = CCDC_PIXFMT_RAW;
> @@ -989,8 +975,8 @@ static int vpfe_config_ccdc_image_format(struct vpfe_device *vpfe)
>
> vpfe_dbg(2, vpfe, "%s:\n", __func__);
>
> - vpfe_dbg(1, vpfe, "pixelformat: %s\n",
> - print_fourcc(vpfe->v_fmt.fmt.pix.pixelformat));
> + vpfe_dbg(1, vpfe, "pixelformat: %4.4s\n",
> + (char *)&vpfe->v_fmt.fmt.pix.pixelformat);

vpfe_dbg(1, vpfe, "pixelformat: %4pE\n",
&vpfe->v_fmt.fmt.pix.pixelformat);

etc...