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SubjectRe: [PATCH v4 6/8] mfd: cros_ec: Support multiple EC in a system
Hello Lee,

Thanks a lot for your feedback.

On 06/03/2015 10:53 AM, Lee Jones wrote:
> On Tue, 02 Jun 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 v3:
>> - Add defines for the EC and PD index constants.
>> - Remove cros_ec_dev_register() and declare the mfd_cells as static structs.
>> Suggested by Lee Jones.
>> - Add a new line before the return statement in cros_ec_dev_register().
>> Suggested by Lee Jones.
>>
>> 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 | 59 +++++++++++--
>> 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, 240 insertions(+), 126 deletions(-)
>>
>> diff --git a/drivers/input/keyboard/cros_ec_keyb.c b/drivers/input/keyboard/cros_ec_keyb.c
>> index 974154a74505..b01966dc7eb3 100644
>> --- a/drivers/input/keyboard/cros_ec_keyb.c
>> +++ b/drivers/input/keyboard/cros_ec_keyb.c
>> @@ -275,7 +275,7 @@ static int cros_ec_keyb_probe(struct platform_device *pdev)
>> ckdev->dev = dev;
>> dev_set_drvdata(&pdev->dev, ckdev);
>>
>> - idev->name = ec->ec_name;
>> + idev->name = CROS_EC_DEV_NAME;
>> idev->phys = ec->phys_name;
>> __set_bit(EV_REP, idev->evbit);
>>
>> diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
>> index 08d82bfc5268..4fbb4ce8f81e 100644
>> --- a/drivers/mfd/cros_ec.c
>> +++ b/drivers/mfd/cros_ec.c
>> @@ -24,11 +24,29 @@
>> #include <linux/mfd/core.h>
>> #include <linux/mfd/cros_ec.h>
>>
>> -static const struct mfd_cell cros_devs[] = {
>> - {
>> - .name = "cros-ec-ctl",
>> - .id = PLATFORM_DEVID_AUTO,
>> - },
>> +#define CROS_EC_DEV_EC_INDEX 0
>> +#define CROS_EC_DEV_PD_INDEX 1
>> +
>> +struct cros_ec_platform ec_p = {
>> + .cmd_offset = EC_CMD_PASSTHRU_OFFSET(CROS_EC_DEV_EC_INDEX),
>> +};
>> +
>> +struct cros_ec_platform pd_p = {
>> + .cmd_offset = EC_CMD_PASSTHRU_OFFSET(CROS_EC_DEV_PD_INDEX),
>> +};
>> +
>> +struct mfd_cell ec_cell = {
>> + .name = "cros-ec-ctl",
>> + .id = PLATFORM_DEVID_AUTO,
>> + .platform_data = &ec_p,
>> + .pdata_size = sizeof(ec_p),
>> +};
>> +
>> +struct mfd_cell ec_pd_cell = {
>> + .name = "cros-ec-ctl",
>> + .id = PLATFORM_DEVID_AUTO,
>> + .platform_data = &pd_p,
>> + .pdata_size = sizeof(pd_p),
>> };
>>
>> int cros_ec_register(struct cros_ec_device *ec_dev)
>> @@ -52,14 +70,39 @@ 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),
>> + if (IS_ENABLED(CONFIG_OF) && dev->of_node)
>> + ec_p.ec_name = of_get_property(dev->of_node, "devname",
>> + NULL);
>
> Has this binding already been accepted? We don't normally allow
> "device name"properties in DT.
>

Sigh, I now noticed that I missed the DT binding change when originally
forward porting the patches from the downstream ChromiumOS tree. I'm so
sorry about that.

ChromiumOS tree has in Documentation/devicetree/bindings/mfd/cros-ec.txt:

Optional properties (All):
- devname: name of the EC. Can be based on its function: for instance,
for Sensor Hub, 'cros_sh', for Power Delivery MCU 'cros_pd'.
If not present, 'cros_ec' can be assumed.

When you say that normally device names are not allowed in DT, do you mean
that "devname" is a too generic property name? (which I totally agree) or
that DT bindings shouldn't have a property to change a device's name for
something more descriptive?

Because for example, the regulator bindings has a "regulator-name" property.
If you agree I can change the property to "google,cros-ec-name" which should
be more precise.

>> + if (!ec_p.ec_name)
>> + ec_p.ec_name = CROS_EC_DEV_NAME;
>> +
>> + err = mfd_add_devices(ec_dev->dev, CROS_EC_DEV_EC_INDEX, &ec_cell, 1,
>> NULL, ec_dev->irq, NULL);
>
> Take a look at how 'id' (second argument) is handled in mfd-core, then
> try to figure out why what you're doing is not correct.
>

I see, so I should not set the struct mfd_cell .id to PLATFORM_DEVID_AUTO and
just pass PLATFORM_DEVID_AUTO to mfd_add_devices() so platform_device_add()
automatically allocates a device ID and sets pdev->id_auto = true.

It was only working because CROS_EC_DEV_EC_INDEX was zero so id + cell->id
was still PLATFORM_DEVID_AUTO but for CROS_EC_DEV_PD_INDEX, it was set to
PLATFORM_DEVID_NONE...

I'll change that, thanks for pointing it out.

>> if (err) {
>> - dev_err(dev, "failed to add mfd devices\n");
>> + dev_err(dev, "failed to add ec\n");
>> return err;
>> }
>
> [...]
>

Best regards,
Javier


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