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From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
To: Hans de Goede <hdegoede@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Guenter Roeck <linux@roeck-us.net>,
	Rob Herring <robh+dt@kernel.org>,
	Zhen Lei <thunder.leizhen@huawei.com>,
	linux-usb@vger.kernel.org
Subject: Re: [PATCH v2 1/3] usb: typec: Add typec_port_register_altmodes_from_fwnode()
Date: Fri, 9 Apr 2021 13:54:34 +0300
Message-ID: <YHAyah2n+yKnAT7d@kuha.fi.intel.com> (raw)
In-Reply-To: <20210408203129.526604-2-hdegoede@redhat.com>

Hi Hans,

On Thu, Apr 08, 2021 at 10:31:27PM +0200, Hans de Goede wrote:
> This can be used by Type-C controller drivers which use a standard
> usb-connector fwnode, with altmodes sub-node, to describe the available
> altmodes.
> 
> Note there are is no devicetree bindings documentation for the altmodes
> node, this is deliberate. ATM the fwnodes used to register the altmodes
> are only used internally to pass platform info from a drivers/platform/x86
> driver to the type-c subsystem.
> 
> When a devicetree user of this functionally comes up and the dt-bindings
> have been hashed out the internal use can be adjusted to match the
> dt-bindings.
> 
> Currently the typec_port_register_altmodes_from_fwnode() function expects
> an "altmodes" child fwnode on port->dev with this "altmodes" fwnode having
> child fwnodes itself with each child containing 2 integer properties:
> 
> 1. A "svid" property, which sets the id of the altmode, e.g. displayport
> altmode has a svid of 0xff01.
> 
> 2. A "vdo" property, typically used as a bitmask describing the
> capabilities of the altmode, the bits in the vdo are specified in the
> specification of the altmode.
> 
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
> Changes in v2:
> - Drop the unnecessary fwnode parameter from
>   typec_port_register_altmodes_from_fwnode()
> - Document the expected "altmodes" fwnode in the commit message for now
>   as v2 of the patch-set drops the dt-bindings since there are not DT
>   users for this yet
> ---
>  drivers/usb/typec/class.c | 55 +++++++++++++++++++++++++++++++++++++++
>  include/linux/usb/typec.h |  6 +++++
>  2 files changed, 61 insertions(+)
> 
> diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c
> index 45f0bf65e9ab..a82344fe1650 100644
> --- a/drivers/usb/typec/class.c
> +++ b/drivers/usb/typec/class.c
> @@ -1978,6 +1978,61 @@ typec_port_register_altmode(struct typec_port *port,
>  }
>  EXPORT_SYMBOL_GPL(typec_port_register_altmode);
>  
> +void typec_port_register_altmodes_from_fwnode(struct typec_port *port,
> +	const struct typec_altmode_ops *ops, void *drvdata,
> +	struct typec_altmode **altmodes, size_t n)

Couldn't we just call this typec_port_register_altmodes()?

> +{
> +	struct fwnode_handle *altmodes_node, *child;
> +	struct typec_altmode_desc desc;
> +	struct typec_altmode *alt;
> +	size_t index = 0;
> +	u32 svid, vdo;
> +	int ret;
> +
> +	altmodes_node = device_get_named_child_node(&port->dev, "altmodes");
> +	if (!altmodes_node)
> +		return; /* No altmodes specified */
> +
> +	child = NULL;
> +	while ((child = fwnode_get_next_child_node(altmodes_node, child))) {

fwnode_for_each_child_node()?

> +		ret = fwnode_property_read_u32(child, "svid", &svid);
> +		if (ret) {
> +			dev_err(&port->dev, "Error reading svid for altmode %s\n",
> +				fwnode_get_name(child));
> +			continue;
> +		}
> +
> +		ret = fwnode_property_read_u32(child, "vdo", &vdo);
> +		if (ret) {
> +			dev_err(&port->dev, "Error reading vdo for altmode %s\n",
> +				fwnode_get_name(child));
> +			continue;
> +		}
> +
> +		if (index >= n) {
> +			dev_err(&port->dev, "Error not enough space for altmode %s\n",
> +				fwnode_get_name(child));
> +			continue;
> +		}
> +
> +		desc.svid = svid;
> +		desc.vdo = vdo;
> +		desc.mode = index + 1;
> +		alt = typec_port_register_altmode(port, &desc);
> +		if (IS_ERR(alt)) {
> +			dev_err(&port->dev, "Error registering altmode %s\n",
> +				fwnode_get_name(child));
> +			continue;
> +		}
> +
> +		alt->ops = ops;
> +		typec_altmode_set_drvdata(alt, drvdata);
> +		altmodes[index] = alt;
> +		index++;
> +	}
> +}
> +EXPORT_SYMBOL_GPL(typec_port_register_altmodes_from_fwnode);

This is OK by me, but I've been wondering if it would be more clear to
just have a function fwnode_for_each_altmode() (I don't know if the
name is good enough).

int fwnode_for_each_altmode(struct fwnode_handle *fwnode,
                            int (*fn)(struct typec_altmode_desc *, void *),
                            void *data)
{
        struct fwnode_handle *altmodes_node, *child;
        struct typec_altmode_desc desc;
	u32 svid, vdo;
	int ret;

	altmodes_node = fwnode_get_named_child_node(fwnode, "altmodes");
	if (!altmodes_node)
		return 0; /* No altmodes specified */

        fwnode_for_each_child_node(altmodes_node, child) {
                ...
                /* read the properties */
                ...

		desc.svid = svid;
		desc.vdo = vdo;
		desc.mode = index + 1;

                /* We need to add this member to struct typec_altmode_desc! */
                desc.fwnode = client;

                ret = fn(&desc, data);
                if (ret)
                        return ret;
        }

        return 0;
}

Something like that. It would leave the registration of the alternate
modes to the drivers, which I think would actually be better.

If there ever is need, this can be also used for other things besides
mode registration.

What do you think?

Br,

-- 
heikki

  reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-08 20:31 [PATCH v2 0/3] " Hans de Goede
2021-04-08 20:31 ` [PATCH v2 1/3] " Hans de Goede
2021-04-09 10:54   ` Heikki Krogerus [this message]
2021-04-09 12:49     ` Hans de Goede
2021-04-09 13:06       ` Heikki Krogerus
2021-04-08 20:31 ` [PATCH v2 2/3] usb: typec: tcpm: Add support for altmodes Hans de Goede
2021-04-08 20:31 ` [PATCH v2 3/3] platform/x86/intel_cht_int33fe: Add displayport altmode fwnode to the connector fwnode Hans de Goede

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