Re: [PATCH v2] platform/chrome: Don't populate lightbar device if it isn't there

From: Enric Balletbo i Serra
Date: Thu Sep 10 2020 - 10:37:26 EST

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In reply to: Guenter Roeck: "Re: [PATCH v2] platform/chrome: Don't populate lightbar device if it isn't there"
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Hi,

On 10/9/20 16:18, Guenter Roeck wrote:
> On Wed, Sep 9, 2020 at 3:42 PM Stephen Boyd <swboyd@xxxxxxxxxxxx> wrote:
>>
>> The cros ec lightbar driver has a check in probe to fail early if the ec
>> device isn't the cros_ec one or if it can't read the lightbar version
>> from the EC. Let's move this check to the place where the lightbar
>> device is registered. This way we don't expose devices that aren't
>> actually there on devices that don't have a lightbar.
>>
>> This should improve memory and possibly performance too because struct
>> devices don't exactly have a small memory footprint and they contribute
>> to suspend/resume regardless of driver attachment.
>>
>> Cc: Gwendal Grignou <gwendal@xxxxxxxxxxxx>
>> Cc: Guenter Roeck <groeck@xxxxxxxxxxxx>
>> Cc: Lee Jones <lee.jones@xxxxxxxxxx>
>> Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
>> ---
>>
>> Changes from v1:
>> * Rebased on linux-next patches to this file
>>
>> drivers/mfd/cros_ec_dev.c | 16 ++-
>> drivers/platform/chrome/cros_ec_lightbar.c | 102 ++------------------
>> drivers/platform/chrome/cros_ec_proto.c | 84 ++++++++++++++++
>> include/linux/platform_data/cros_ec_proto.h | 4 +
>> 4 files changed, 111 insertions(+), 95 deletions(-)
>>
>> diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
>> index d07b43d7c761..9e98b2ec5d92 100644
>> --- a/drivers/mfd/cros_ec_dev.c
>> +++ b/drivers/mfd/cros_ec_dev.c
>> @@ -74,6 +74,10 @@ static const struct mfd_cell cros_ec_cec_cells[] = {
>> { .name = "cros-ec-cec", },
>> };
>>
>> +static const struct mfd_cell cros_ec_lightbar_cells[] = {
>> + { .name = "cros-ec-lightbar", },
>> +};
>> +
>> static const struct mfd_cell cros_ec_rtc_cells[] = {
>> { .name = "cros-ec-rtc", },
>> };
>> @@ -112,7 +116,6 @@ static const struct cros_feature_to_cells cros_subdevices[] = {
>> static const struct mfd_cell cros_ec_platform_cells[] = {
>> { .name = "cros-ec-chardev", },
>> { .name = "cros-ec-debugfs", },
>> - { .name = "cros-ec-lightbar", },
>> { .name = "cros-ec-sysfs", },
>> };
>>
>> @@ -206,6 +209,17 @@ static int ec_device_probe(struct platform_device *pdev)
>> }
>> }
>>
>> + if (!strcmp(ec_platform->ec_name, CROS_EC_DEV_NAME) &&
>> + !cros_ec_get_lightbar_version(ec, NULL, NULL)) {
>
> Any idea why the lightbar code doesn't use cros_ec_check_features() ?
> There is a definition for EC_FEATURE_LIGHTBAR, but it doesn't seem to
> be used. It would be much more convenient if that feature check could
> be used instead of moving the get_lightbar_version command and its
> helper function around.
>

IIRC it was to support a very old device, the Pixel Chromebook (Link). This flag
is not set in this device but has a lightbar, hence we had this 'weird' way to
detect the lightbar.

> Thanks,
> Guenter
>
>> + retval = mfd_add_hotplug_devices(ec->dev,
>> + cros_ec_lightbar_cells,
>> + ARRAY_SIZE(cros_ec_lightbar_cells));
>> + if (retval)
>> + dev_err(ec->dev,
>> + "failed to add lightbar device: %d\n",
>> + retval);
>> + }
>> +
>> /*
>> * The PD notifier driver cell is separate since it only needs to be
>> * explicitly added on platforms that don't have the PD notifier ACPI
>> diff --git a/drivers/platform/chrome/cros_ec_lightbar.c b/drivers/platform/chrome/cros_ec_lightbar.c
>> index de8dfb12e486..a7cfde90c8e5 100644
>> --- a/drivers/platform/chrome/cros_ec_lightbar.c
>> +++ b/drivers/platform/chrome/cros_ec_lightbar.c
>> @@ -82,77 +82,6 @@ static int lb_throttle(void)
>> return ret;
>> }
>>
>> -static struct cros_ec_command *alloc_lightbar_cmd_msg(struct cros_ec_dev *ec)
>> -{
>> - struct cros_ec_command *msg;
>> - int len;
>> -
>> - len = max(sizeof(struct ec_params_lightbar),
>> - sizeof(struct ec_response_lightbar));
>> -
>> - msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
>> - if (!msg)
>> - return NULL;
>> -
>> - msg->version = 0;
>> - msg->command = EC_CMD_LIGHTBAR_CMD + ec->cmd_offset;
>> - msg->outsize = sizeof(struct ec_params_lightbar);
>> - msg->insize = sizeof(struct ec_response_lightbar);
>> -
>> - return msg;
>> -}
>> -
>> -static int get_lightbar_version(struct cros_ec_dev *ec,
>> - uint32_t *ver_ptr, uint32_t *flg_ptr)
>> -{
>> - struct ec_params_lightbar *param;
>> - struct ec_response_lightbar *resp;
>> - struct cros_ec_command *msg;
>> - int ret;
>> -
>> - msg = alloc_lightbar_cmd_msg(ec);
>> - if (!msg)
>> - return 0;
>> -
>> - param = (struct ec_params_lightbar *)msg->data;
>> - param->cmd = LIGHTBAR_CMD_VERSION;
>> - msg->outsize = sizeof(param->cmd);
>> - msg->result = sizeof(resp->version);
>> - ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
>> - if (ret < 0 && ret != -EINVAL) {
>> - ret = 0;
>> - goto exit;
>> - }
>> -
>> - switch (msg->result) {
>> - case EC_RES_INVALID_PARAM:
>> - /* Pixel had no version command. */
>> - if (ver_ptr)
>> - *ver_ptr = 0;
>> - if (flg_ptr)
>> - *flg_ptr = 0;
>> - ret = 1;
>> - goto exit;
>> -
>> - case EC_RES_SUCCESS:
>> - resp = (struct ec_response_lightbar *)msg->data;
>> -
>> - /* Future devices w/lightbars should implement this command */
>> - if (ver_ptr)
>> - *ver_ptr = resp->version.num;
>> - if (flg_ptr)
>> - *flg_ptr = resp->version.flags;
>> - ret = 1;
>> - goto exit;
>> - }
>> -
>> - /* Anything else (ie, EC_RES_INVALID_COMMAND) - no lightbar */
>> - ret = 0;
>> -exit:
>> - kfree(msg);
>> - return ret;
>> -}
>> -
>> static ssize_t version_show(struct device *dev,
>> struct device_attribute *attr, char *buf)
>> {
>> @@ -165,7 +94,7 @@ static ssize_t version_show(struct device *dev,
>> return ret;
>>
>> /* This should always succeed, because we check during init. */
>> - if (!get_lightbar_version(ec, &version, &flags))
>> + if (cros_ec_get_lightbar_version(ec, &version, &flags))
>> return -EIO;
>>
>> return scnprintf(buf, PAGE_SIZE, "%d %d\n", version, flags);
>> @@ -184,7 +113,7 @@ static ssize_t brightness_store(struct device *dev,
>> if (kstrtouint(buf, 0, &val))
>> return -EINVAL;
>>
>> - msg = alloc_lightbar_cmd_msg(ec);
>> + msg = cros_ec_alloc_lightbar_cmd_msg(ec);
>> if (!msg)
>> return -ENOMEM;
>>
>> @@ -222,7 +151,7 @@ static ssize_t led_rgb_store(struct device *dev, struct device_attribute *attr,
>> unsigned int val[4];
>> int ret, i = 0, j = 0, ok = 0;
>>
>> - msg = alloc_lightbar_cmd_msg(ec);
>> + msg = cros_ec_alloc_lightbar_cmd_msg(ec);
>> if (!msg)
>> return -ENOMEM;
>>
>> @@ -289,7 +218,7 @@ static ssize_t sequence_show(struct device *dev,
>> int ret;
>> struct cros_ec_dev *ec = to_cros_ec_dev(dev);
>>
>> - msg = alloc_lightbar_cmd_msg(ec);
>> + msg = cros_ec_alloc_lightbar_cmd_msg(ec);
>> if (!msg)
>> return -ENOMEM;
>>
>> @@ -324,7 +253,7 @@ static int lb_send_empty_cmd(struct cros_ec_dev *ec, uint8_t cmd)
>> struct cros_ec_command *msg;
>> int ret;
>>
>> - msg = alloc_lightbar_cmd_msg(ec);
>> + msg = cros_ec_alloc_lightbar_cmd_msg(ec);
>> if (!msg)
>> return -ENOMEM;
>>
>> @@ -352,7 +281,7 @@ static int lb_manual_suspend_ctrl(struct cros_ec_dev *ec, uint8_t enable)
>> struct cros_ec_command *msg;
>> int ret;
>>
>> - msg = alloc_lightbar_cmd_msg(ec);
>> + msg = cros_ec_alloc_lightbar_cmd_msg(ec);
>> if (!msg)
>> return -ENOMEM;
>>
>> @@ -399,7 +328,7 @@ static ssize_t sequence_store(struct device *dev, struct device_attribute *attr,
>> return ret;
>> }
>>
>> - msg = alloc_lightbar_cmd_msg(ec);
>> + msg = cros_ec_alloc_lightbar_cmd_msg(ec);
>> if (!msg)
>> return -ENOMEM;
>>
>> @@ -444,7 +373,7 @@ static ssize_t program_store(struct device *dev, struct device_attribute *attr,
>> return -EINVAL;
>> }
>>
>> - msg = alloc_lightbar_cmd_msg(ec);
>> + msg = cros_ec_alloc_lightbar_cmd_msg(ec);
>> if (!msg)
>> return -ENOMEM;
>>
>> @@ -531,24 +460,9 @@ static struct attribute_group cros_ec_lightbar_attr_group = {
>> static int cros_ec_lightbar_probe(struct platform_device *pd)
>> {
>> struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
>> - struct cros_ec_platform *pdata = dev_get_platdata(ec_dev->dev);
>> struct device *dev = &pd->dev;
>> int ret;
>>
>> - /*
>> - * Only instantiate the lightbar if the EC name is 'cros_ec'. Other EC
>> - * devices like 'cros_pd' doesn't have a lightbar.
>> - */
>> - if (strcmp(pdata->ec_name, CROS_EC_DEV_NAME) != 0)
>> - return -ENODEV;
>> -
>> - /*
>> - * Ask then for the lightbar version, if it's 0 then the 'cros_ec'
>> - * doesn't have a lightbar.
>> - */
>> - if (!get_lightbar_version(ec_dev, NULL, NULL))
>> - return -ENODEV;
>> -
>> /* Take control of the lightbar from the EC. */
>> lb_manual_suspend_ctrl(ec_dev, 1);
>>
>> diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
>> index dda182132a6a..a08747eec36a 100644
>> --- a/drivers/platform/chrome/cros_ec_proto.c
>> +++ b/drivers/platform/chrome/cros_ec_proto.c
>> @@ -922,3 +922,87 @@ int cros_ec_get_sensor_count(struct cros_ec_dev *ec)
>> return sensor_count;
>> }
>> EXPORT_SYMBOL_GPL(cros_ec_get_sensor_count);
>> +
>> +struct cros_ec_command *cros_ec_alloc_lightbar_cmd_msg(struct cros_ec_dev *ec)
>> +{
>> + struct cros_ec_command *msg;
>> + int len;
>> +
>> + len = max(sizeof(struct ec_params_lightbar),
>> + sizeof(struct ec_response_lightbar));
>> +
>> + msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
>> + if (!msg)
>> + return NULL;
>> +
>> + msg->version = 0;
>> + msg->command = EC_CMD_LIGHTBAR_CMD + ec->cmd_offset;
>> + msg->outsize = sizeof(struct ec_params_lightbar);
>> + msg->insize = sizeof(struct ec_response_lightbar);
>> +
>> + return msg;
>> +}
>> +EXPORT_SYMBOL_GPL(cros_ec_alloc_lightbar_cmd_msg);
>> +
>> +/**
>> + * cros_ec_get_lightbar_version() - Get the EC lightbar version
>> + *
>> + * @ec: EC device, does not have to be connected directly to the AP,
>> + * can be daisy chained through another device.
>> + * @ver_ptr: Detected lightbar version number
>> + * @flag_ptr: Detected lightbar flags
>> + *
>> + * Call this function to determine the EC's lightbar version and flags
>> + * information. If it doesn't exist then this function returns a negative
>> + * error value.
>> + *
>> + * Return: 0 on success, negative errno on failure to detect a lightbar.
>> + */
>> +int cros_ec_get_lightbar_version(struct cros_ec_dev *ec, uint32_t *ver_ptr,
>> + uint32_t *flg_ptr)
>> +{
>> + struct ec_params_lightbar *param;
>> + struct ec_response_lightbar *resp;
>> + struct cros_ec_command *msg;
>> + int ret;
>> +
>> + msg = cros_ec_alloc_lightbar_cmd_msg(ec);
>> + if (!msg)
>> + return -ENOMEM;
>> +
>> + param = (struct ec_params_lightbar *)msg->data;
>> + param->cmd = LIGHTBAR_CMD_VERSION;
>> + msg->outsize = sizeof(param->cmd);
>> + msg->result = sizeof(resp->version);
>> + ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
>> + if (ret < 0 && ret != -EINVAL)
>> + goto exit;
>> +
>> + switch (msg->result) {
>> + case EC_RES_INVALID_PARAM:
>> + /* Pixel had no version command. */
>> + if (ver_ptr)
>> + *ver_ptr = 0;
>> + if (flg_ptr)
>> + *flg_ptr = 0;
>> + ret = 0;
>> + break;
>> + case EC_RES_SUCCESS:
>> + resp = (struct ec_response_lightbar *)msg->data;
>> +
>> + /* Future devices w/lightbars should implement this command */
>> + if (ver_ptr)
>> + *ver_ptr = resp->version.num;
>> + if (flg_ptr)
>> + *flg_ptr = resp->version.flags;
>> + ret = 0;
>> + break;
>> + default:
>> + /* Anything else (ie, EC_RES_INVALID_COMMAND) - no lightbar */
>> + ret = -ENODEV;
>> + }
>> +exit:
>> + kfree(msg);
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(cros_ec_get_lightbar_version);
>> diff --git a/include/linux/platform_data/cros_ec_proto.h b/include/linux/platform_data/cros_ec_proto.h
>> index 4a415ae851ef..50221254956c 100644
>> --- a/include/linux/platform_data/cros_ec_proto.h
>> +++ b/include/linux/platform_data/cros_ec_proto.h
>> @@ -229,6 +229,10 @@ u32 cros_ec_get_host_event(struct cros_ec_device *ec_dev);
>>
>> int cros_ec_check_features(struct cros_ec_dev *ec, int feature);
>>
>> +struct cros_ec_command *cros_ec_alloc_lightbar_cmd_msg(struct cros_ec_dev *ec);
>> +int cros_ec_get_lightbar_version(struct cros_ec_dev *ec, uint32_t *ver_ptr,
>> + uint32_t *flg_ptr);
>> +
>> int cros_ec_get_sensor_count(struct cros_ec_dev *ec);
>>
>> /**
>>
>> base-commit: 1e7913ff5f9f1b73146ad8522958bd266f22a510
>> --
>> Sent by a computer, using git, on the internet
>>

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