On 18.12.2019 13:06, Chanwoo Choi wrote:
> 2019년 12월 18일 (수) 오후 7:14, Leonard Crestez <leonard.crestez@xxxxxxx>님이 작성:
>> On 17.12.2019 02:55, Chanwoo Choi wrote:
>>> On 12/17/19 12:00 AM, Leonard Crestez wrote:
>>>> On 13.12.2019 06:22, Chanwoo Choi wrote:
>>>>> On 11/15/19 5:09 AM, Leonard Crestez wrote:
>>>>>> There is no single device which can represent the imx interconnect.
>>>>>> Instead of adding a virtual one just make the main &noc act as the
>>>>>> global interconnect provider.
>>>>>>
>>>>>> The imx interconnect provider driver will scale the NOC and DDRC based
>>>>>> on bandwidth request. More scalable nodes can be added in the future,
>>>>>> for example for audio/display/vpu/gpu NICs.
>>>>>>
>>>>>> Signed-off-by: Leonard Crestez <leonard.crestez@xxxxxxx>
>>>>>> ---
>>>>>> drivers/devfreq/imx-devfreq.c | 37 +++++++++++++++++++++++++++++++++++
>>>>>> 1 file changed, 37 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/devfreq/imx-devfreq.c b/drivers/devfreq/imx-devfreq.c
>>>>>> index 620b344e87aa..585d340c0f6e 100644
>>>>>> --- a/drivers/devfreq/imx-devfreq.c
>>>>>> +++ b/drivers/devfreq/imx-devfreq.c
>>>>>> @@ -15,10 +15,11 @@
>>>>>> struct imx_devfreq {
>>>>>> struct devfreq_dev_profile profile;
>>>>>> struct devfreq *devfreq;
>>>>>> struct clk *clk;
>>>>>> struct devfreq_passive_data passive_data;
>>>>>> + struct platform_device *icc_pdev;
>>>>>> };
>>>>>>
>>>>>> static int imx_devfreq_target(struct device *dev,
>>>>>> unsigned long *freq, u32 flags)
>>>>>> {
>>>>>> @@ -60,11 +61,40 @@ static int imx_devfreq_get_dev_status(struct device *dev,
>>>>>> return 0;
>>>>>> }
>>>>>>
>>>>>> static void imx_devfreq_exit(struct device *dev)
>>>>>> {
>>>>>> + struct imx_devfreq *priv = dev_get_drvdata(dev);
>>>>>> +
>>>>>> dev_pm_opp_of_remove_table(dev);
>>>>>> + platform_device_unregister(priv->icc_pdev);
>>>>>> +}
>>>>>> +
>>>>>> +/* imx_devfreq_init_icc() - register matching icc provider if required */
>>>>>> +static int imx_devfreq_init_icc(struct device *dev)
>>>>>> +{
>>>>>> + struct imx_devfreq *priv = dev_get_drvdata(dev);
>>>>>> + const char *icc_driver_name;
>>>>>> +
>>>>>> + if (!IS_ENABLED(CONFIG_INTERCONNECT_IMX))
>>>>>> + return 0;
>>>>>
>>>>> It is not proper to check the enable state of CONFIG_INTERCONNECT_IMX configuration
>>>>> on device driver. Why don't you add the 'select CONFIG_INTERCONNECT_IMX' on Kconfig?
>>>>
>>>> Because it's optional.
>>>>
>>>> You can disable interconnect support and just tweak frequencies using
>>>> the devfreq sysfs API. But indeed would only really be useful for debugging.
>>>
>>> Even if it's optional, I don't prefer to use 'IS_ENABLED' macro.
>>>
>>> Generally, add or delete the property or value at DT file
>>> to either enable or disable the some feature provided by device driver
>>> instead of checking the configuration.
>>>
>>> If user adds the property/value related to interconnect
>>> and imx-bus.c configuration is enabled, the behavior
>>> related to interconnect on imx-bus.c doesn't work. It make some confusion.
>>
>> Maybe I could print a warning if #interconnect-cells is present but
>> CONFIG_INTERCONNECT_IMX is off?
>
> Actually, user might think that if imx-bus.c is enabled
> , CONFIG_INTERCONNECT_MIX is enabled.
> Because, the dt binding document of imx-bus.c will
> contain the property for interconnect.
>
> If device driver support the various feature,
> the device driver have to enable all configuration
> in order to support the features for user.
>> An explicit select in Kconfig seems like a pointless limitation but in
>> practice it would almost never be useful to build one without the other.
>
> This patch is for the some CONFIG_INTERCONNECT_IMX driver.
> I don't understand why is not meaningful to select CONFIG_INTERCONNECT_IMX
> in Kconfig?
One issue is that the interconnect graph is described per-soc and there
are per-soc config options while imx-bus applies to all. So the "if"
condition is not sufficient either; if the per-soc interconnect driver
is omitted then the platform device will be added but no driver will be
ever be found.
There are ways around this: for example all of imx interconnect could be
built as a single module. But I think it's reasonable for devices to be
partially functional if some config options are missing and heavy config
customization sometimes requires a bit of debugging.
There are various issues when building the current series as "m" but I
can solve them and post a final patch which sets all the relevant
options on "m" in arm64 defconfig. The it will all "just work" out of
the box.
>>> The imx-bus.c have to add the 'select CONFIG_INTERCONNECT_IMX'
>>> and hand over the right which use the interconnect feature or not, to user.
>>>
>>> If there are any requirement to add the additional property
>>> to check whether interconnect feature will be used or not,
>>> you can add the extra property. But, I think that it is enough
>>> to check the '#interconnect-cells'.
>>>
>>> In result, I think that it is right to decide the usage of feature
>>> of device driver by user on Devicetree.
>>>
>>>>
>>>>>> + if (!of_get_property(dev->of_node, "#interconnect-cells", 0))
>>>>>> + return 0;
>>>>>> +
>>>>>> + icc_driver_name = of_device_get_match_data(dev);
>>>>>> + if (!icc_driver_name)
>>>>>> + return 0;
>>>>>> +
>>>>>> + priv->icc_pdev = platform_device_register_data(
>>>>>> + dev, icc_driver_name, 0, NULL, 0);
>>>>>> + if (IS_ERR(priv->icc_pdev)) {
>>>>>> + dev_err(dev, "failed to register icc provider %s: %ld\n",
>>>>>> + icc_driver_name, PTR_ERR(priv->devfreq));
>>>>>> + return PTR_ERR(priv->devfreq);
>>>>>> + }
>>>>>> +
>>>>>> + return 0;
>>>>>> }
>>>>>>
>>>>>> static int imx_devfreq_probe(struct platform_device *pdev)
>>>>>> {
>>>>>> struct device *dev = &pdev->dev;
>>>>>> @@ -120,18 +150,25 @@ static int imx_devfreq_probe(struct platform_device *pdev)
>>>>>> ret = PTR_ERR(priv->devfreq);
>>>>>> dev_err(dev, "failed to add devfreq device: %d\n", ret);
>>>>>> goto err;
>>>>>> }
>>>>>>
>>>>>> + ret = imx_devfreq_init_icc(dev);
>>>>>> + if (ret)
>>>>>> + goto err;
>>>>>> +
>>>>>> return 0;
>>>>>>
>>>>>> err:
>>>>>> dev_pm_opp_of_remove_table(dev);
>>>>>> return ret;
>>>>>> }
>>>>>>
>>>>>> static const struct of_device_id imx_devfreq_of_match[] = {
>>>>>> + { .compatible = "fsl,imx8mq-noc", .data = "imx8mq-interconnect", },
>>>>>> + { .compatible = "fsl,imx8mm-noc", .data = "imx8mm-interconnect", },
>>>>>> + { .compatible = "fsl,imx8mn-noc", .data = "imx8mn-interconnect", },
>>>>>> { .compatible = "fsl,imx8m-noc", },
>>>>>> { .compatible = "fsl,imx8m-nic", },
>>>>>> { /* sentinel */ },
>>>>>> };
>>>>>> MODULE_DEVICE_TABLE(of, imx_devfreq_of_match);
