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Date:   Mon, 9 Sep 2019 12:12:15 -0500
From:   Benoit Parrot <bparrot@ti.com>
To:     Joe Perches <joe@perches.com>
CC:     Hans Verkuil <hverkuil@xs4all.nl>,
        Prabhakar Lad <prabhakar.csengg@gmail.com>,
        <linux-media@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [Patch 10/13] media: am437x-vpfe: Remove print_fourcc helper
Message-ID: <20190909171215.2cyiulubzxcjqmf7@ti.com>
References: <20190909162743.30114-1-bparrot@ti.com>
 <20190909162743.30114-11-bparrot@ti.com>
 <7d870b0119afa378dc68c710670b9b550ef5bdd4.camel@perches.com>
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Joe Perches <joe@perches.com> wrote on Mon [2019-Sep-09 09:39:37 -0700]:
> 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);
> 

Thanks Joe, I was not aware of this feature.
I'll update this patch.

Benoit

> >  
> >  	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...
> 
>