On Mon, Dec 16, 2019 at 6:51 PM Ben Hutchings ben@decadent.org.uk 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@ti.com
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@ti.com Cc: Adam Ford aford173@gmail.com Link: https://patchwork.freedesktop.org/patch/msgid/20191002122542.8449-1-tomi.val... Tested-by: Adam Ford aford173@gmail.com Reviewed-by: Jyri Sarha jsarha@ti.com [bwh: Backported to 3.16: adjust filename, context] Signed-off-by: Ben Hutchings ben@decadent.org.uk
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,