Re: [PATCH v3 6/7] platform/chrome: cros_ec_typec: Thunderbolt support

From: Abhishek Pandit-Subedi
Date: Fri Dec 06 2024 - 17:24:03 EST

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On Thu, Nov 14, 2024 at 2:55 AM Dmitry Baryshkov
<dmitry.baryshkov@xxxxxxxxxx> wrote:
>
> On Wed, Nov 13, 2024 at 08:01:57PM -0800, Abhishek Pandit-Subedi wrote:
> > On Fri, Nov 8, 2024 at 10:41 PM Dmitry Baryshkov
> > <dmitry.baryshkov@xxxxxxxxxx> wrote:
> > >
> > > On Thu, Nov 07, 2024 at 11:29:59AM -0800, Abhishek Pandit-Subedi wrote:
> > > > Add support for entering and exiting Thunderbolt alt-mode using AP
> > > > driven alt-mode.
> > > >
> > > > Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@xxxxxxxxxxxx>
> > > > ---
> > > >
> > > > Changes in v3:
> > > > - Fix usage of TBT sid and mode.
> > > > - Removed unused vdm operations during altmode registration
> > > >
> > > > Changes in v2:
> > > > - Refactored thunderbolt support into cros_typec_altmode.c
> > > >
> > > > drivers/platform/chrome/Makefile | 3 +
> > > > drivers/platform/chrome/cros_ec_typec.c | 23 +++---
> > > > drivers/platform/chrome/cros_typec_altmode.c | 85 ++++++++++++++++++++
> > > > drivers/platform/chrome/cros_typec_altmode.h | 14 ++++
> > > > 4 files changed, 114 insertions(+), 11 deletions(-)
> > > >
> > > > diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
> > > > index 2f90d4db8099..b9b1281de063 100644
> > > > --- a/drivers/platform/chrome/Makefile
> > > > +++ b/drivers/platform/chrome/Makefile
> > > > @@ -21,6 +21,9 @@ cros-ec-typec-objs := cros_ec_typec.o cros_typec_vdm.o
> > > > ifneq ($(CONFIG_TYPEC_DP_ALTMODE),)
> > > > cros-ec-typec-objs += cros_typec_altmode.o
> > > > endif
> > > > +ifneq ($(CONFIG_TYPEC_TBT_ALTMODE),)
> > > > + cros-ec-typec-objs += cros_typec_altmode.o
> > > > +endif
> > >
> > > Doesn't this also result in the object file being included twice and
> > > thus in a duplicate symbols declaration?
> >
> > I was trying to figure out how to add this file if either of those
> > config options existed in
> > https://docs.kernel.org/kbuild/makefiles.html#built-in-object-goals-obj-y
> > and it says, "Duplicates in the lists are allowed: the first instance
> > will be linked into built-in.a and succeeding instances will be
> > ignored."
> >
> > Is there a preferred way of doing the following in the Makefile:
> > if (defined(CONFIG_TYPEC_TBT_ALTMODE) ||
> > defined(CONFIG_TYPEC_DP_ALTMODE)) {...}
> >
> > I briefly considered the following and dropped it because it is
> > terrible readability-wise:
> > ifneq ($(CONFIG_TYPEC_TBT_ALTMODE)$(CONFIG_TYPEC_DP_ALTMODE),)
>
> The usual way would to define new Kconfig symbol:
>
> config CROS_EC_TYPEC_ALTMODES
> bool # Note, no description here, don't show in menuconfig
> help
> Selectable symbol to enable altmodes
>
> config CROS_EC_TYPEC
> ...
> select CROS_EC_TYPEC_ALTMODES if CONFIG_TYPEC_DP_ALTMODE
> select CROS_EC_TYPEC_ALTMODES if CONFIG_TYPEC_TBT_ALTMODE
> ...
>
> ----
>
> cros-ec-typec-$(CONFIG_CROS_EC_TYPEC_ALTMODES) += cros_typec_altmode.o
>
> >
> > >
> > > > obj-$(CONFIG_CROS_EC_TYPEC) += cros-ec-typec.o
> > > >
> > > > obj-$(CONFIG_CROS_EC_LPC) += cros_ec_lpcs.o
> > > > diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
> > > > index 3a6f5f2717b9..558b618df63c 100644
> > > > --- a/drivers/platform/chrome/cros_ec_typec.c
> > > > +++ b/drivers/platform/chrome/cros_ec_typec.c
> > > > @@ -302,18 +302,19 @@ static int cros_typec_register_port_altmodes(struct cros_typec_data *typec,
> > > >
> > > > /*
> > > > * Register TBT compatibility alt mode. The EC will not enter the mode
> > > > - * if it doesn't support it, so it's safe to register it unconditionally
> > > > - * here for now.
> > > > + * if it doesn't support it and it will not enter automatically by
> > > > + * design so we can use the |ap_driven_altmode| feature to check if we
> > > > + * should register it.
> > > > */
> > > > - memset(&desc, 0, sizeof(desc));
> > > > - desc.svid = USB_TYPEC_TBT_SID;
> > > > - desc.mode = TYPEC_ANY_MODE;
> > > > - amode = typec_port_register_altmode(port->port, &desc);
> > > > - if (IS_ERR(amode))
> > > > - return PTR_ERR(amode);
> > > > - port->port_altmode[CROS_EC_ALTMODE_TBT] = amode;
> > > > - typec_altmode_set_drvdata(amode, port);
> > > > - amode->ops = &port_amode_ops;
> > > > + if (typec->ap_driven_altmode) {
> > > > + memset(&desc, 0, sizeof(desc));
> > > > + desc.svid = USB_TYPEC_TBT_SID;
> > > > + desc.mode = TBT_MODE;
> > > > + amode = cros_typec_register_thunderbolt(port, &desc);
> > > > + if (IS_ERR(amode))
> > > > + return PTR_ERR(amode);
> > > > + port->port_altmode[CROS_EC_ALTMODE_TBT] = amode;
> > > > + }
> > > >
> > > > port->state.alt = NULL;
> > > > port->state.mode = TYPEC_STATE_USB;
> > > > diff --git a/drivers/platform/chrome/cros_typec_altmode.c b/drivers/platform/chrome/cros_typec_altmode.c
> > > > index 3598b8a6ceee..9cf2cef6c277 100644
> > > > --- a/drivers/platform/chrome/cros_typec_altmode.c
> > > > +++ b/drivers/platform/chrome/cros_typec_altmode.c
> > > > @@ -8,6 +8,7 @@
> > > > #include "cros_ec_typec.h"
> > > >
> > > > #include <linux/usb/typec_dp.h>
> > > > +#include <linux/usb/typec_tbt.h>
> > > > #include <linux/usb/pd_vdo.h>
> > > >
> > > > #include "cros_typec_altmode.h"
> > > > @@ -67,6 +68,8 @@ static int cros_typec_altmode_enter(struct typec_altmode *alt, u32 *vdo)
> > > >
> > > > if (data->sid == USB_TYPEC_DP_SID)
> > > > req.mode_to_enter = CROS_EC_ALTMODE_DP;
> > > > + else if (data->sid == USB_TYPEC_TBT_SID)
> > > > + req.mode_to_enter = CROS_EC_ALTMODE_TBT;
> > > > else
> > > > return -EOPNOTSUPP;
> > > >
> > > > @@ -196,6 +199,53 @@ static int cros_typec_displayport_vdm(struct typec_altmode *alt, u32 header,
> > > > return 0;
> > > > }
> > > >
> > > > +static int cros_typec_thunderbolt_vdm(struct typec_altmode *alt, u32 header,
> > > > + const u32 *data, int count)
> > > > +{
> > > > + struct cros_typec_altmode_data *adata = typec_altmode_get_drvdata(alt);
> > > > +
> > > > + int cmd_type = PD_VDO_CMDT(header);
> > > > + int cmd = PD_VDO_CMD(header);
> > > > + int svdm_version;
> > >
> > > I suppose that with the current approach this misses the ap_mode_entry
> > > check. If it gets moved to cros_typec_altmode_vdm(), then it should be
> > > okay.
> >
> > We don't register the thunderbolt port driver if ap_mode_entry is
> > false so it's an unnecessary check.
>
> Why don't you register it? It would allow userspace to understand, what
> is happening, e.g. that the Type-C has switched to the TBT mode.

Cros-EC does not support automatic entry of Thunderbolt/USB4 (i.e. all
firmware that supports TBT/USB4 MUST set ap_mode_entry).

>
> >
> > >
> > > > +
> > > > + svdm_version = typec_altmode_get_svdm_version(alt);
> > > > + if (svdm_version < 0)
> > > > + return svdm_version;
> > > > +
> > > > + switch (cmd_type) {
> > > > + case CMDT_INIT:
> > > > + if (PD_VDO_SVDM_VER(header) < svdm_version) {
> > > > + typec_partner_set_svdm_version(adata->port->partner,
> > > > + PD_VDO_SVDM_VER(header));
> > > > + svdm_version = PD_VDO_SVDM_VER(header);
> > > > + }
> > > > +
> > > > + adata->header = VDO(adata->sid, 1, svdm_version, cmd);
> > > > + adata->header |= VDO_OPOS(adata->mode);
> > > > +
> > > > + switch (cmd) {
> > > > + case CMD_ENTER_MODE:
> > > > + /* Don't respond to the enter mode vdm because it
> > > > + * triggers mux configuration. This is handled directly
> > > > + * by the cros_ec_typec driver so the Thunderbolt driver
> > > > + * doesn't need to be involved.
> > > > + */
> > > > + break;
> > > > + default:
> > > > + adata->header |= VDO_CMDT(CMDT_RSP_ACK);
> > > > + schedule_work(&adata->work);
> > > > + break;
> > > > + }
> > > > +
> > > > + break;
> > > > + default:
> > > > + break;
> > > > + }
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > +
> > > > static int cros_typec_altmode_vdm(struct typec_altmode *alt, u32 header,
> > > > const u32 *data, int count)
> > > > {
> > > > @@ -204,6 +254,9 @@ static int cros_typec_altmode_vdm(struct typec_altmode *alt, u32 header,
> > > > if (adata->sid == USB_TYPEC_DP_SID)
> > > > return cros_typec_displayport_vdm(alt, header, data, count);
> > > >
> > > > + if (adata->sid == USB_TYPEC_TBT_SID)
> > > > + return cros_typec_thunderbolt_vdm(alt, header, data, count);
> > > > +
> > > > return -EINVAL;
> > > > }
> > > >
> > > > @@ -273,3 +326,35 @@ cros_typec_register_displayport(struct cros_typec_port *port,
> > > > return alt;
> > > > }
> > > > #endif
> > > > +
> > > > +#if IS_ENABLED(CONFIG_TYPEC_TBT_ALTMODE)
> > > > +struct typec_altmode *
> > > > +cros_typec_register_thunderbolt(struct cros_typec_port *port,
> > > > + struct typec_altmode_desc *desc)
> > > > +{
> > > > + struct typec_altmode *alt;
> > > > + struct cros_typec_altmode_data *data;
> > > > +
> > > > + alt = typec_port_register_altmode(port->port, desc);
> > > > + if (IS_ERR(alt))
> > > > + return alt;
> > > > +
> > > > + data = devm_kzalloc(&alt->dev, sizeof(*data), GFP_KERNEL);
> > > > + if (!data) {
> > > > + typec_unregister_altmode(alt);
> > > > + return ERR_PTR(-ENOMEM);
> > > > + }
> > > > +
> > > > + INIT_WORK(&data->work, cros_typec_altmode_work);
> > > > + data->alt = alt;
> > > > + data->port = port;
> > > > + data->ap_mode_entry = true;
> > > > + data->sid = desc->svid;
> > > > + data->mode = desc->mode;
> > > > +
> > > > + typec_altmode_set_ops(alt, &cros_typec_altmode_ops);
> > > > + typec_altmode_set_drvdata(alt, data);
> > > > +
> > > > + return alt;
> > > > +}
> > > > +#endif
> > > > diff --git a/drivers/platform/chrome/cros_typec_altmode.h b/drivers/platform/chrome/cros_typec_altmode.h
> > > > index c6f8fb02c99c..810b553ddcd8 100644
> > > > --- a/drivers/platform/chrome/cros_typec_altmode.h
> > > > +++ b/drivers/platform/chrome/cros_typec_altmode.h
> > > > @@ -31,4 +31,18 @@ static inline int cros_typec_displayport_status_update(struct typec_altmode *alt
> > > > return 0;
> > > > }
> > > > #endif
> > > > +
> > > > +#if IS_ENABLED(CONFIG_TYPEC_TBT_ALTMODE)
> > > > +struct typec_altmode *
> > > > +cros_typec_register_thunderbolt(struct cros_typec_port *port,
> > > > + struct typec_altmode_desc *desc);
> > > > +#else
> > > > +static inline struct typec_altmode *
> > > > +cros_typec_register_thunderbolt(struct cros_typec_port *port,
> > > > + struct typec_altmode_desc *desc)
> > > > +{
> > > > + return typec_port_register_altmode(port->port, desc);
> > > > +}
> > > > +#endif
> > > > +
> > > > #endif /* __CROS_TYPEC_ALTMODE_H__ */
> > > > --
> > > > 2.47.0.277.g8800431eea-goog
> > > >
> > >
> > > --
> > > With best wishes
> > > Dmitry
>
> --
> With best wishes
> Dmitry

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