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 <[email protected]>
Cc: Tomi Valkeinen <[email protected]>
Cc: [email protected] # 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,
--
2.17.1
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 <[email protected]>
> Cc: Tomi Valkeinen <[email protected]>
> Cc: [email protected] # 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 <[email protected]>
Tomi
--
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
On Mon, Oct 21, 2019 at 3:44 AM Tomi Valkeinen <[email protected]> wrote:
>
> 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 <[email protected]>
> > Cc: Tomi Valkeinen <[email protected]>
> > Cc: [email protected] # 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?
That is correct. The patch I did for 4.9+ didn't apply cleanly on
4.4, so I had to do a separate patch for 4.4.
adam
>
> Reviewed-by: Tomi Valkeinen <[email protected]>
>
> Tomi
>
> --
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
On Fri, Oct 18, 2019 at 8:05 AM Adam Ford <[email protected]> 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 <[email protected]>
> Cc: Tomi Valkeinen <[email protected]>
> Cc: [email protected] # linux-4.4.y only
This is basically the same patch as the only Tomi reviewed for 4.9,
but it is based on 4.4.
Is there any way these can be integrated?
thank you,
adam
>
> 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,
> --
> 2.17.1
>