Re: [PATCH 1/1] mx3fb: support pan display with fb_set_var

[Liu Ying]

2012/5/30, Liu Ying <Ying.Liu@xxxxxxxxxxxxx>:
> Users may call FBIOPUT_VSCREENINFO ioctrl to do pan display.
> This ioctrl relies on fb_set_var() to do the job. fb_set_var()
> calls custom fb_set_par() method and then calls custom
> fb_pan_display() method. The current implementation of mx3fb
> reinitializes IPU display controller every time the custom
> fb_set_par() method is called, which makes the display flash
> if fb_set_var() is called to do panning frequently. The custom
> fb_pan_display() method checks if the current xoffset and
> yoffset are different from previous ones before doing actual
> panning, which prevents the panning from happening within the
> fb_set_var() context. This patch checks new var info to decide
> whether we really need to reinitialize IPU display controller.
> We ignore xoffset and yoffset update because it doesn't require
> to reinitialize the controller. Users may specify activate field
> of var info with FB_ACTIVATE_NOW and FB_ACTIVATE_FORCE to
> reinialize the controller by force. Meanwhile, this patch removes
> the check in custom fb_pan_display() method mentioned before to
> have the panning work within fb_set_var() context. It doesn't
> hurt to do panning again if there is no update for xoffset and
> yoffset.
>
> Signed-off-by: Liu Ying <Ying.Liu@xxxxxxxxxxxxx>
> ---
>  drivers/video/mx3fb.c |   31 +++++++++++++++++++++++++++----
>  1 files changed, 27 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/video/mx3fb.c b/drivers/video/mx3fb.c
> index e3406ab..86daabe 100644
> --- a/drivers/video/mx3fb.c
> +++ b/drivers/video/mx3fb.c
> @@ -269,6 +269,8 @@ struct mx3fb_info {
>  	struct scatterlist		sg[2];
>
>  	u32				sync;	/* preserve var->sync flags */
> +
> +	struct fb_var_screeninfo	cur_var; /* current var info */
>  };
>
>  static void mx3fb_dma_done(void *);
> @@ -721,6 +723,26 @@ static void mx3fb_dma_done(void *arg)
>  	complete(&mx3_fbi->flip_cmpl);
>  }
>
> +static bool fb_need_not_to_set_par(struct fb_info *fbi)
> +{
> +	struct mx3fb_info *mx3_fbi = fbi->par;
> +	struct fb_var_screeninfo old_var = mx3_fbi->cur_var;
> +	struct fb_var_screeninfo new_var = fbi->var;
> +
> +	if ((fbi->var.activate & FB_ACTIVATE_FORCE) &&
> +	    (fbi->var.activate & FB_ACTIVATE_MASK) == FB_ACTIVATE_NOW)
> +		return false;
> +
> +	/*
> +	 * Ignore xoffset and yoffset update,
> +	 * because pan display handles this case.
> +	 */
> +	old_var.xoffset = new_var.xoffset;
> +	old_var.yoffset = new_var.yoffset;
> +
> +	return !memcmp(&old_var, &new_var, sizeof(struct fb_var_screeninfo));
> +}
> +
>  static int __set_par(struct fb_info *fbi, bool lock)
>  {
>  	u32 mem_len;
> @@ -732,6 +754,9 @@ static int __set_par(struct fb_info *fbi, bool lock)
>  	struct idmac_video_param *video = &ichan->params.video;
>  	struct scatterlist *sg = mx3_fbi->sg;
>
> +	if (fb_need_not_to_set_par(fbi))
> +		return 0;
> +
>  	/* Total cleanup */
>  	if (mx3_fbi->txd)
>  		sdc_disable_channel(mx3_fbi);
> @@ -808,6 +833,8 @@ static int __set_par(struct fb_info *fbi, bool lock)
>  	if (mx3_fbi->blank == FB_BLANK_UNBLANK)
>  		sdc_enable_channel(mx3_fbi);
>
> +	mx3_fbi->cur_var = fbi->var;
> +
>  	return 0;
>  }
>
> @@ -1068,10 +1095,6 @@ static int mx3fb_pan_display(struct fb_var_screeninfo
> *var,
>  		return -EINVAL;
>  	}
>
> -	if (fbi->var.xoffset == var->xoffset &&
> -	    fbi->var.yoffset == var->yoffset)
> -		return 0;	/* No change, do nothing */
> -
>  	y_bottom = var->yoffset;
>
>  	if (!(var->vmode & FB_VMODE_YWRAP))
> --
> 1.7.1
>
>
> --
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The patch is present here for a period of time.
Can someone help to review this?
Thanks.

-- 
Best Regards,
Liu Ying
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