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    SubjectRe: [PATCH 20/20] pinctrl: Enhance mapping table to support pin config operations
    On Mon, Feb 27, 2012 at 11:02:01AM -0800, Stephen Warren wrote:
    > Dong Aisheng wrote at Monday, February 27, 2012 5:21 AM:
    > > On Sun, Feb 19, 2012 at 11:46:00PM -0700, Stephen Warren wrote:
    > > > The pinctrl mapping table can now contain entries to:
    > > > * Set the mux function of a pin group
    > > > * Apply a set of pin config options to a pin or a group
    > > >
    > > > This allows pinctrl_select_state() to apply pin configs settings as well
    > > > as mux settings.
    > > >
    > > > Signed-off-by: Stephen Warren <swarren@nvidia.com>
    > ...
    > > > +The mapping table may also contain pin configuration entries. It's common for
    > > > +each pin/group to have a number of configuration entries that affect it, so
    > > > +the table entries for configuration reference an array of config parameters
    > > > +and values. An example using the convenience macros is shown below:
    > > > +
    > > > +static unsigned long i2c_grp_configs[] = {
    > > > + FOO_PIN_DRIVEN,
    > > > + FOO_PIN_PULLUP,
    > > > +};
    > > > +
    > > > +static unsigned long i2c_pin_configs[] = {
    > > > + FOO_OPEN_COLLECTOR,
    > > > + FOO_SLEW_RATE_SLOW,
    > > > +};
    > > > +
    > > > +static struct pinctrl_map __initdata mapping[] = {
    > > > + PIN_MAP_MUX_GROUP("foo-i2c.0", "default", "pinctrl-foo", "i2c0", "i2c0"),
    > > > + PIN_MAP_MUX_CONFIGS_GROUP("foo-i2c.0", "default", "pinctrl-foo", "i2c0", i2c_grp_configs),
    > > > + PIN_MAP_MUX_CONFIGS_PIN("foo-i2c.0", "default", "pinctrl-foo", "i2c0scl", i2c_pin_configs),
    > > > + PIN_MAP_MUX_CONFIGS_PIN("foo-i2c.0", "default", "pinctrl-foo", "i2c0sda", i2c_pin_configs),
    > >
    > > I still have not read all over this patch.
    > > But one question i'm considering is that
    > > will this way here also work for "virtual" group?
    > > For example, the virtual group "i2c_grp_configs" may actually contains
    > > the config for each pin in that group?
    > > The core will handle this difference or let each driver to handle it?
    >
    > Since the core has no knowledge of virtual groups, everything has to be
    > handled inside the pin controller driver: When the core asks the driver
    > to enumerate the groups it supports, those virtual groups must be included
    > in the list. The mapping table may contain entries to configure those
    > virtual groups, which will be passed on to the driver to implement as it
    > sees fit. So, in short, yes, I believe this handles virtual groups just
    > fine.
    >
    Ok, great.

    > > > @@ -1022,7 +1074,7 @@ Since it may be common to request the core to hog a few always-applicable
    > > > mux settings on the primary pin controller, there is a convenience macro for
    > > > this:
    > > >
    > > > -PIN_MAP_SYS_HOG("active", "pinctrl-foo", "power_func")
    > >
    > > Hmm?
    > > Why remove this one?
    >
    > In the patch I posted, I simplified the mapping table macros by replacing
    > all mux entries with a single macro PIN_MAP_MUX_GROUP(). However, I've
    > since modified the patch to include a number of special-case macros, so
    > this macro has been added back (albeit under a slightly different name).
    >
    Sounds good.

    > > > +int pinctrl_get_pin_id(struct pinctrl_dev *pctldev,
    > > > + const char *pin)
    > > > +{
    > > > + unsigned int i;
    > > > +
    > > > + for (i = 0; i < pctldev->desc->npins; i++) {
    > > > + if (pctldev->desc->pins[i].name == NULL)
    > > > + continue;
    > > > + if (!strcmp(pin, pctldev->desc->pins[i].name)) {
    > > > + dev_dbg(pctldev->dev, "found pin id %u for %s\n",
    > > > + i, pin);
    > > > + return i;
    > >
    > > It looks actually this is not a PIN id.
    > > It's just the index of the pin array.
    > > Pin has its own id:
    > > struct pinctrl_pin_desc {
    > > unsigned number;
    > > const char *name;
    > > };
    >
    > I guess I should just delete this function and call pin_get_from_name()
    > instead.
    >
    > However, this does raise one question:
    >
    > Right now, pin_config_set() calls pin_get_from_name() to find the pin
    > ID of a pin. This returns that "number" field in the struct above. This
    > is then passed to the pin controller driver's pin_config_set() callback.
    > Hence, the pin ID value passed to pin_config_set() can't be used to index
    > into the driver's own pin_desc array if the pin numbers are sparse. Is
    > that intended? I suppose it's OK since any driver-specific information
    > about each pin can't be stored in the pin_desc array anyway, since that
    > array has a standard type without space for driver-specific data, and
    > any driver-specific array would probably be indexed by the values in the
    > .number field, not the pin_desc array index.
    It's indeed.

    Regards
    Dong Aisheng



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