Re: [PATCH] omapfb: dss: Fix max fclk divider for omap36xx

From: Bartlomiej Zolnierkiewicz
Date: Fri Jul 10 2020 - 10:24:34 EST



On 6/30/20 8:26 PM, 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@xxxxxxxxxxxxxxx> #4.9+
> Signed-off-by: Adam Ford <aford173@xxxxxxxxx>

Applied to drm-misc-next tree, thanks.

(I marked patch as applicable to stable 4.5+ while merging)

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

> ---
> 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,
>