Re: [PATCH v3 6/7] mfd: cros_ec: Support multiple EC in a system

Lee Jones
2015-05-28T14:26:16Z

On Thu, 28 May 2015, Javier Martinez Canillas wrote:

> Hello Lee,
>
> Thanks a lot for your feedback.
>
> On 05/27/2015 11:11 AM, Lee Jones wrote:
> > On Fri, 22 May 2015, Javier Martinez Canillas wrote:
> >
> >> From: Gwendal Grignou <gwendal@chromium.org>
> >>
> >> Chromebooks can have more than one Embedded Controller so the
> >> cros_ec device id has to be incremented for each EC registered.
> >>
> >> Add code to handle multiple EC. First ec found is cros-ec0,
> >> second cros-ec1 and so on.
> >>
> >> Add a new structure to represent multiple EC as different char
> >> devices (e.g: /dev/cros_ec, /dev/cros_pd). It connects to
> >> cros_ec_device and allows sysfs inferface for cros_pd.
> >>
> >> Also reduce number of allocated objects, make chromeos sysfs
> >> class object a static and add refcounting to prevent object
> >> deletion while command is in progress.
> >>
> >> Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
> >> Reviewed-by: Dmitry Torokhov <dtor@chromium.org>
> >> Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
> >> ---
> >>
> >> Changes since v2: None
> >>
> >> Changes since v1:
> >> - Squash patch that adds support to represent EC's as different
> >> char devices (e.g: /dev/cros_ec, /dev/cros_pd):
> >> https://chromium-review.googlesource.com/#/c/217297/
> >> Suggested by Gwendal Grignou
> >> - Use cros_ec instead of cros-ec in the subject line to be consistent.
> >> Suggested by Gwendal Grignou
> >> ---
> >> drivers/input/keyboard/cros_ec_keyb.c | 2 +-
> >> drivers/mfd/cros_ec.c | 66 +++++++++++++--
> >> drivers/mfd/cros_ec_i2c.c | 1 -
> >> drivers/mfd/cros_ec_spi.c | 1 -
> >> drivers/platform/chrome/cros_ec_dev.c | 128 ++++++++++++++++++++---------
> >> drivers/platform/chrome/cros_ec_dev.h | 7 --
> >> drivers/platform/chrome/cros_ec_lightbar.c | 75 +++++++++--------
> >> drivers/platform/chrome/cros_ec_lpc.c | 1 -
> >> drivers/platform/chrome/cros_ec_sysfs.c | 48 +++++------
> >> include/linux/mfd/cros_ec.h | 44 ++++++++--
> >> 10 files changed, 247 insertions(+), 126 deletions(-)

[...]

> >> @@ -52,14 +88,28 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
> >>
> >> cros_ec_query_all(ec_dev);
> >>
> >> - err = mfd_add_devices(dev, 0, cros_devs,
> >> - ARRAY_SIZE(cros_devs),
> >> - NULL, ec_dev->irq, NULL);
> >> + err = cros_ec_dev_register(ec_dev, dev_id++, 0);
> >> if (err) {
> >> - dev_err(dev, "failed to add mfd devices\n");
> >> + dev_err(dev, "failed to add ec\n");
> >> return err;
> >> }
> >>
> >> + if (ec_dev->max_passthru) {
> >> + /*
> >> + * Register a PD device as well on top of this device.
> >> + * We make the following assumptions:
> >> + * - behind an EC, we have a pd
> >> + * - only one device added.
> >> + * - the EC is responsive at init time (it is not true for a
> >> + * sensor hub.
> >> + */
> >> + err = cros_ec_dev_register(ec_dev, dev_id++, 1);
> >
> > I don't really like this devidx business. Just keep it simple and
> > define more than one mfd_cell structure.
>
> I explained to you that this is done because the number of cells depends on
> the system. I can have an array of mfd_cell structures and use the index to
> register but I don't think that is easier to understand.

Keep it simple. Create a static struct for each and:

mfd_add_devices(ec_cell)

if (ec_dev->max_passthru)
mfd_add_devices(ec_pd_cell)

> >> + if (err) {
> >> + dev_err(dev, "failed to add additional ec\n");
> >> + return err;
> >> + }
> >> + }
> >> +
> >> if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
> >> err = of_platform_populate(dev->of_node, NULL, NULL, dev);
> >> if (err) {
> >
>
> Best regards,
> Javier

--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
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