linux-kernel - Re: [PATCH 1/2] drm/sun4i: tcon: fix check of tcon->panel null pointer

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Message-ID: <e8344f9e-54af-e287-c992-4494d8a54025@micronovasrl.com>
Date:   Wed, 3 Oct 2018 00:00:55 +0200
From:   Giulio Benetti <giulio.benetti@...ronovasrl.com>
To:     Maxime Ripard <maxime.ripard@...tlin.com>
Cc:     David Airlie <airlied@...ux.ie>, Chen-Yu Tsai <wens@...e.org>,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: Re: [PATCH 1/2] drm/sun4i: tcon: fix check of tcon->panel null
 pointer

Sorry for sending twice(and top posting), but I was not subscribed to 
dri-devel ML, so patchwork was not aware of these 2 patches.

Best regards
-- 
Giulio Benetti
CTO

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Il 02/10/2018 23:59, Giulio Benetti ha scritto:
> At the moment, the check of tcon->panel to be valid is wrong. IS_ERR()
> has been used, but that macro doesn't check if tcon->panel pointer is
> null or not, but check if tcon->panel is between -1 and -4095(MAX_ERRNO).
> 
> Remove IS_ERR() from tcon->panel checking and let "if (tcon->panel)" as
> condition to check if it's a pointer not null.
> 
> Signed-off-by: Giulio Benetti <giulio.benetti@...ronovasrl.com>
> ---
>   drivers/gpu/drm/sun4i/sun4i_tcon.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> index c78cd35a1294..e4b3bd0307ef 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> @@ -555,7 +555,7 @@ static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon,
>   	 * Following code is a way to avoid quirks all around TCON
>   	 * and DOTCLOCK drivers.
>   	 */
> -	if (!IS_ERR(tcon->panel)) {
> +	if (tcon->panel) {
>   		struct drm_panel *panel = tcon->panel;
>   		struct drm_connector *connector = panel->connector;
>   		struct drm_display_info display_info = connector->display_info;
>