Re: [RFC PATCH] fbdev: mxsfb: use framebuffer_alloc in the correct way

[Stefan Agner <stefan@agner.ch>]

On 2018-01-04 22:14, Michael Trimarchi wrote:
> framebuffer_alloc allocated the fb_info struct plus the extra
> par and set fb_info->par pointer equal to this extra par. We
> can refer the mxcfb_info from fb_info->par

Hm, so we wasted sizeof(struct fb_info). Interesting.

> 
> Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
> ---
>  drivers/video/fbdev/mxsfb.c | 27 +++++++++++++--------------
>  1 file changed, 13 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/video/fbdev/mxsfb.c b/drivers/video/fbdev/mxsfb.c
> index 79b1dc7..fa24ddc 100644
> --- a/drivers/video/fbdev/mxsfb.c
> +++ b/drivers/video/fbdev/mxsfb.c
> @@ -169,7 +169,6 @@ struct mxsfb_devdata {
>  };
>  
>  struct mxsfb_info {
> -	struct fb_info fb_info;
>  	struct platform_device *pdev;
>  	struct clk *clk;
>  	struct clk *clk_axi;
> @@ -208,7 +207,7 @@ static const struct mxsfb_devdata mxsfb_devdata[] = {
>  	},
>  };
>  
> -#define to_imxfb_host(x) (container_of(x, struct mxsfb_info, fb_info))
> +#define to_imxfb_host(x) (((struct fb_info *)(x))->par)

This type cast in unnecessary or even harmful. x should always be
fb_info.

Since we do not use container_of anymore we can also get rid of the
macro entirely. Other drivers also access ->par directly. Just use:

struct mxsfb_info *host = fb_info->par;

--
Stefan

>  
>  /* mask and shift depends on architecture */
>  static inline u32 set_hsync_pulse_width(struct mxsfb_info *host, unsigned val)
> @@ -622,10 +621,10 @@ static struct fb_ops mxsfb_ops = {
>  	.fb_imageblit = cfb_imageblit,
>  };
>  
> -static int mxsfb_restore_mode(struct mxsfb_info *host,
> +static int mxsfb_restore_mode(struct fb_info *fb_info,
>  			struct fb_videomode *vmode)
>  {
> -	struct fb_info *fb_info = &host->fb_info;
> +	struct mxsfb_info *host = to_imxfb_host(fb_info);
>  	unsigned line_count;
>  	unsigned period;
>  	unsigned long pa, fbsize;
> @@ -726,10 +725,10 @@ static int mxsfb_restore_mode(struct mxsfb_info *host,
>  	return ret;
>  }
>  
> -static int mxsfb_init_fbinfo_dt(struct mxsfb_info *host,
> +static int mxsfb_init_fbinfo_dt(struct fb_info *fb_info,
>  				struct fb_videomode *vmode)
>  {
> -	struct fb_info *fb_info = &host->fb_info;
> +	struct mxsfb_info *host = to_imxfb_host(fb_info);
>  	struct fb_var_screeninfo *var = &fb_info->var;
>  	struct device *dev = &host->pdev->dev;
>  	struct device_node *np = host->pdev->dev.of_node;
> @@ -805,12 +804,12 @@ static int mxsfb_init_fbinfo_dt(struct mxsfb_info *host,
>  	return ret;
>  }
>  
> -static int mxsfb_init_fbinfo(struct mxsfb_info *host,
> +static int mxsfb_init_fbinfo(struct fb_info *fb_info,
>  			struct fb_videomode *vmode)
>  {
>  	int ret;
> +	struct mxsfb_info *host = to_imxfb_host(fb_info);
>  	struct device *dev = &host->pdev->dev;
> -	struct fb_info *fb_info = &host->fb_info;
>  	struct fb_var_screeninfo *var = &fb_info->var;
>  	dma_addr_t fb_phys;
>  	void *fb_virt;
> @@ -824,7 +823,7 @@ static int mxsfb_init_fbinfo(struct mxsfb_info *host,
>  	fb_info->fix.visual = FB_VISUAL_TRUECOLOR,
>  	fb_info->fix.accel = FB_ACCEL_NONE;
>  
> -	ret = mxsfb_init_fbinfo_dt(host, vmode);
> +	ret = mxsfb_init_fbinfo_dt(fb_info, vmode);
>  	if (ret)
>  		return ret;
>  
> @@ -843,16 +842,16 @@ static int mxsfb_init_fbinfo(struct mxsfb_info *host,
>  	fb_info->screen_base = fb_virt;
>  	fb_info->screen_size = fb_info->fix.smem_len = fb_size;
>  
> -	if (mxsfb_restore_mode(host, vmode))
> +	if (mxsfb_restore_mode(fb_info, vmode))
>  		memset(fb_virt, 0, fb_size);
>  
>  	return 0;
>  }
>  
> -static void mxsfb_free_videomem(struct mxsfb_info *host)
> +static void mxsfb_free_videomem(struct fb_info *fb_info)
>  {
> +	struct mxsfb_info *host = to_imxfb_host(fb_info);
>  	struct device *dev = &host->pdev->dev;
> -	struct fb_info *fb_info = &host->fb_info;
>  
>  	dma_free_wc(dev, fb_info->screen_size, fb_info->screen_base,
>  		    fb_info->fix.smem_start);
> @@ -941,7 +940,7 @@ static int mxsfb_probe(struct platform_device *pdev)
>  		goto fb_release;
>  	}
>  
> -	ret = mxsfb_init_fbinfo(host, mode);
> +	ret = mxsfb_init_fbinfo(fb_info, mode);
>  	if (ret != 0)
>  		goto fb_release;
>  
> @@ -988,7 +987,7 @@ static int mxsfb_remove(struct platform_device *pdev)
>  		mxsfb_disable_controller(fb_info);
>  
>  	unregister_framebuffer(fb_info);
> -	mxsfb_free_videomem(host);
> +	mxsfb_free_videomem(fb_info);
>  
>  	framebuffer_release(fb_info);