Re: [PATCH 2/2] usb: typec: qcom-pmic-typec: register drm_bridge

[Dmitry Baryshkov]

On 09/07/2023 14:25, Bryan O'Donoghue wrote:
> On 09/07/2023 04:48, Dmitry Baryshkov wrote:
> > The current approach to handling DP on bridge-enabled platforms requires
> > a chain of DP bridges up to the USB-C connector. Register a last DRM
> > bridge for such chain.
> >
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > ---
> >   drivers/usb/typec/tcpm/qcom/qcom_pmic_typec.c | 25 +++++++++++++++++++
> >   1 file changed, 25 insertions(+)
> >
> > diff --git a/drivers/usb/typec/tcpm/qcom/qcom_pmic_typec.c 
> > b/drivers/usb/typec/tcpm/qcom/qcom_pmic_typec.c
> > index a905160dd860..ca832a28176e 100644
> > --- a/drivers/usb/typec/tcpm/qcom/qcom_pmic_typec.c
> > +++ b/drivers/usb/typec/tcpm/qcom/qcom_pmic_typec.c
> > @@ -17,6 +17,9 @@
> >   #include <linux/usb/role.h>
> >   #include <linux/usb/tcpm.h>
> >   #include <linux/usb/typec_mux.h>
> > +
> > +#include <drm/drm_bridge.h>
> > +
> >   #include "qcom_pmic_typec_pdphy.h"
> >   #include "qcom_pmic_typec_port.h"
> > @@ -33,6 +36,7 @@ struct pmic_typec {
> >       struct pmic_typec_port    *pmic_typec_port;
> >       bool            vbus_enabled;
> >       struct mutex        lock;        /* VBUS state serialization */
> > +    struct drm_bridge    bridge;
> >   };
> >   #define tcpc_to_tcpm(_tcpc_) container_of(_tcpc_, struct pmic_typec, 
> > tcpc)
> > @@ -146,6 +150,16 @@ static int qcom_pmic_typec_init(struct tcpc_dev 
> > *tcpc)
> >       return 0;
> >   }
> > +static int qcom_pmic_typec_attach(struct drm_bridge *bridge,
> > +                     enum drm_bridge_attach_flags flags)
> > +{
> > +    return flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR ? 0 : -EINVAL;
> > +}
>
> Should that be -ENODEV instead ?

No. This bridge doesn't implement older bridge API, where the bridge had 
to create drm_connector itself. This implementation requires 
DRM_BRIDGE_ATTACH_NO_CONNECTOR and it is invalid to call it without this 
flag. Other bridges which have been converted to 
DRM_BRIDGE_ATTACH_NO_CONNECTOR implement the same semantics.

> > +
> > +static const struct drm_bridge_funcs qcom_pmic_typec_bridge_funcs = {
> > +    .attach = qcom_pmic_typec_attach,
> > +};
> > +
> >   static int qcom_pmic_typec_probe(struct platform_device *pdev)
> >   {
> >       struct pmic_typec *tcpm;
> > @@ -208,6 +222,17 @@ static int qcom_pmic_typec_probe(struct 
> > platform_device *pdev)
> >       mutex_init(&tcpm->lock);
> >       platform_set_drvdata(pdev, tcpm);
> > +    tcpm->bridge.funcs = &qcom_pmic_typec_bridge_funcs;
> > +#if CONFIG_OF
> > +    tcpm->bridge.of_node = of_get_child_by_name(dev->of_node, 
> > "connector");
> > +#endif
> > +    tcpm->bridge.ops = DRM_BRIDGE_OP_HPD;
> > +    tcpm->bridge.type = DRM_MODE_CONNECTOR_USB;
> > +
> > +    ret = devm_drm_bridge_add(dev, &tcpm->bridge);
>
> I think you need to either
>
> Kconfig + depends on DRM
>
> or
>
> #if CONFIG_DRM

I guess I'm too used to always having DRM. This will need both Kconfig 
and source code parts. Will fix it in v2.

> https://www.spinics.net/lists/kernel/msg4773470.html
>
> Kconfig for preference
>
> ---
> bod

--
With best wishes
Dmitry