On 18.01.2023 10:11, Dmitry Baryshkov wrote: > Do not create device link for clock controllers. Some of the clocks > provided to the device via OF can be the clocks that are just parents to > the clocks provided by this clock controller. Clock subsystem already > has support for handling missing clock parents correctly (clock > orphans). Later when the parent clock is registered, clocks get > populated properly. > > An example of the system where this matters is the SDM8450 MTP board > (see arch/arm64/boot/dts/qcom/sdm845-mtp.dts). Here the dispcc uses > clocks provided by dsi0_phy and dsi1_phy device tree nodes. However the > dispcc itself provides clocks to both PHYs, to the PHY parent device, > etc. With just dsi0_phy in place devlink is able to break the > dependency, but with two PHYs, dispcc doesn't get probed at all, thus > breaking display support. > > Cc: Bjorn Andersson <andersson@xxxxxxxxxx> > Cc: Stephen Boyd <sboyd@xxxxxxxxxx> > Cc: Saravana Kannan <saravanak@xxxxxxxxxx> > Cc: Abel Vesa <abel.vesa@xxxxxxxxxx> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> > --- Tested-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> # SM8350 PDX215 Konrad > > This patch has been posted a year ago in January 2022 ([1]). Since that time > Saravana failed to produce patches to assist in debugging the issue > ([2]) or to fix the issue ([3]). The issue we observe has been described > by Abel at ([4]). As we work on adding support for Dual DSI > configurations, the issue becomes more and more important, since binding > the whole display subsystem fails. > > Currently the qcom/sdm845-mtp board is already broken and I've just > posted a patch adding Dual DSI variant for the qcom/sdm845-db845c board > ([5]). > > [1] https://lore.kernel.org/lkml/20211125183622.597177-1-dmitry.baryshkov@xxxxxxxxxx/ > [2] https://lore.kernel.org/lkml/CAA8EJpqELXvRMPWJdTLCURjwkcMxyPDPj1tVZPkdOT_JVQb4-w@xxxxxxxxxxxxxx/ > [3] https://lore.kernel.org/all/CAGETcx8F0wP+RA0KpjOJeZfc=DVG-MbM_=SkRHD4UhD2ReL7Kw@xxxxxxxxxxxxxx/ > [4] https://lore.kernel.org/all/YrsdLQrOtg1qdaoE@xxxxxxxxxx/ > [5] https://lore.kernel.org/all/20230118082048.2198715-1-dmitry.baryshkov@xxxxxxxxxx/ > > --- > drivers/of/property.c | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/drivers/of/property.c b/drivers/of/property.c > index 134cfc980b70..d323bf26a613 100644 > --- a/drivers/of/property.c > +++ b/drivers/of/property.c > @@ -1297,7 +1297,6 @@ struct supplier_bindings { > bool node_not_dev; > }; > > -DEFINE_SIMPLE_PROP(clocks, "clocks", "#clock-cells") > DEFINE_SIMPLE_PROP(interconnects, "interconnects", "#interconnect-cells") > DEFINE_SIMPLE_PROP(iommus, "iommus", "#iommu-cells") > DEFINE_SIMPLE_PROP(mboxes, "mboxes", "#mbox-cells") > @@ -1327,6 +1326,21 @@ DEFINE_SIMPLE_PROP(backlight, "backlight", NULL) > DEFINE_SUFFIX_PROP(regulators, "-supply", NULL) > DEFINE_SUFFIX_PROP(gpio, "-gpio", "#gpio-cells") > > +static struct device_node *parse_clocks(struct device_node *np, > + const char *prop_name, int index) > +{ > + /* > + * Do not create clock-related device links for clocks controllers, > + * clock orphans will handle missing clock parents automatically. > + */ > + if (!strcmp(prop_name, "clocks") && > + of_find_property(np, "#clock-cells", NULL)) > + return NULL; > + > + return parse_prop_cells(np, prop_name, index, "clocks", > + "#clock-cells"); > +} > + > static struct device_node *parse_gpios(struct device_node *np, > const char *prop_name, int index) > {
