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SubjectRe: [PATCH] fbdev/omap: fix max fclk divider for omap36xx
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On 18/10/2019 16:05, Adam Ford wrote:
> The OMAP36xx and AM/DM37x TRMs say that the maximum divider for DSS fclk
> (in CM_CLKSEL_DSS) is 32. Experimentation shows that this is not
> correct, and using divider of 32 breaks DSS with a flood or underflows
> and sync losts. Dividers up to 31 seem to work fine.
>
> There is another patch to the DT files to limit the divider correctly,
> but as the DSS driver also needs to know the maximum divider to be able
> to iteratively find good rates, we also need to do the fix in the DSS
> driver.
>
> Signed-off-by: Adam Ford <aford173@gmail.com>
> Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Cc: stable@vger.kernel.org # linux-4.4.y only
>
> diff --git a/drivers/video/fbdev/omap2/dss/dss.c b/drivers/video/fbdev/omap2/dss/dss.c
> index 9200a8668b49..a57c3a5f4bf8 100644
> --- a/drivers/video/fbdev/omap2/dss/dss.c
> +++ b/drivers/video/fbdev/omap2/dss/dss.c
> @@ -843,7 +843,7 @@ 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,
>

To clarify, this patch is only for the v4.4 stable, whereas the previous
patch was for next merge window and v4.9+ stable. Right?

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

Tomi

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