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Subject: Re: [PATCH] omapfb: dss: Fix max fclk divider for omap36xx
To:     Adam Ford <aford173@gmail.com>, <linux-fbdev@vger.kernel.org>
CC:     <stable@vger.kernel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        Dave Airlie <airlied@gmail.com>,
        Rob Clark <robdclark@gmail.com>, <linux-omap@vger.kernel.org>,
        <dri-devel@lists.freedesktop.org>, <linux-kernel@vger.kernel.org>
References: <20200630182636.439015-1-aford173@gmail.com>
From:   Tomi Valkeinen <tomi.valkeinen@ti.com>
Message-ID: <b9052a12-af5a-c1b9-5b86-907eac470cf8@ti.com>
Date:   Fri, 3 Jul 2020 10:17:29 +0300
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On 30/06/2020 21:26, Adam Ford wrote:
> The drm/omap driver was fixed to correct an issue where using a
> divider of 32 breaks the DSS despite the TRM stating 32 is a valid
> number.  Through experimentation, it appears that 31 works, and
> it is consistent with the value used by the drm/omap driver.
> 
> This patch fixes the divider for fbdev driver instead of the drm.
> 
> Fixes: f76ee892a99e ("omapfb: copy omapdss & displays for omapfb")
> 
> Cc: <stable@vger.kernel.org> #4.9+
> Signed-off-by: Adam Ford <aford173@gmail.com>
> ---
> Linux 4.4 will need a similar patch, but it doesn't apply cleanly.
> 
> The DRM version of this same fix is:
> e2c4ed148cf3 ("drm/omap: fix max fclk divider for omap36xx")
> 
> 
> diff --git a/drivers/video/fbdev/omap2/omapfb/dss/dss.c b/drivers/video/fbdev/omap2/omapfb/dss/dss.c
> index 7252d22dd117..bfc5c4c5a26a 100644
> --- a/drivers/video/fbdev/omap2/omapfb/dss/dss.c
> +++ b/drivers/video/fbdev/omap2/omapfb/dss/dss.c
> @@ -833,7 +833,7 @@ static const struct dss_features omap34xx_dss_feats = {
>   };
>   
>   static const struct dss_features omap3630_dss_feats = {
> -	.fck_div_max		=	32,
> +	.fck_div_max		=	31,
>   	.dss_fck_multiplier	=	1,
>   	.parent_clk_name	=	"dpll4_ck",
>   	.dpi_select_source	=	&dss_dpi_select_source_omap2_omap3,
> 

Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

  Tomi

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