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From:   Fabio Estevam <festevam@gmail.com>
Date:   Tue, 8 Sep 2020 10:01:20 -0300
Message-ID: <CAOMZO5Amaxi-rU44b_q4+6k4vtOoCOmbKgiDJ0r3tEi4zkZB=w@mail.gmail.com>
Subject: Re: [PATCH v2] drm: mxsfb: check framebuffer pitch
To:     Stefan Agner <stefan@agner.ch>
Cc:     Marek Vasut <marex@denx.de>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Sascha Hauer <kernel@pengutronix.de>,
        Tomi Valkeinen <tomi.valkeinen@ti.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        DRI mailing list <dri-devel@lists.freedesktop.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
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Hi Stefan,

On Tue, Sep 8, 2020 at 9:56 AM Stefan Agner <stefan@agner.ch> wrote:
>
> The lcdif IP does not support a framebuffer pitch (stride) other than
> framebuffer width. Check for equality and reject the framebuffer
> otherwise.
>
> This prevents a distorted picture when using 640x800 and running the
> Mesa graphics stack. Mesa tires to use a cache aligned stride, which
> leads at that particular resolution to width != stride. Currently
> Mesa has no fallback behavior, but rejecting this configuration allows
> userspace to handle the issue correctly.

What about adding a Fixes tag so that it can be backported to old
stable kernels?

Thanks