On Mon, Dec 16, 2019 at 6:51 PM Ben Hutchings <ben@xxxxxxxxxxxxxxx> wrote: > > 3.16.80-rc1 review patch. If anyone has any objections, please let me know. > > ------------------ I tried to do the same for 4.4, 4.9 and 4.14, but I haven't seen anything applied yet. I just looked at the upstream fbdev driver for the dss, and it's still showing 32 and the value. Even though the fbdev driver isn't enabled by default any more, I wonder if it should be fixed as part of the justification for the backports. adam > > From: Tomi Valkeinen <tomi.valkeinen@xxxxxx> > > commit e2c4ed148cf3ec8669a1d90dc66966028e5fad70 upstream. > > 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: Tomi Valkeinen <tomi.valkeinen@xxxxxx> > Cc: Adam Ford <aford173@xxxxxxxxx> > Link: https://patchwork.freedesktop.org/patch/msgid/20191002122542.8449-1-tomi.valkeinen@xxxxxx > Tested-by: Adam Ford <aford173@xxxxxxxxx> > Reviewed-by: Jyri Sarha <jsarha@xxxxxx> > [bwh: Backported to 3.16: adjust filename, context] > Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> > --- > drivers/video/fbdev/omap2/dss/dss.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/drivers/video/fbdev/omap2/dss/dss.c > +++ b/drivers/video/fbdev/omap2/dss/dss.c > @@ -708,7 +708,7 @@ static const struct dss_features omap34x > }; > > static const struct dss_features omap3630_dss_feats __initconst = { > - .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, >
