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SubjectRe: [RFC PATCH 5/5] media: platform: Add Chrome OS EC CEC driver
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On 05/15/18 10:28, Neil Armstrong wrote:
>>>>> + int ret;
>>>>> +
>>>>> + cros_ec_cec = devm_kzalloc(&pdev->dev, sizeof(*cros_ec_cec),
>>>>> + GFP_KERNEL);
>>>>> + if (!cros_ec_cec)
>>>>> + return -ENOMEM;
>>>>> +
>>>>> + platform_set_drvdata(pdev, cros_ec_cec);
>>>>> + cros_ec_cec->cros_ec = cros_ec;
>>>>> +
>>>>> + ret = cros_ec_cec_get_notifier(&cros_ec_cec->notify);
>>>>> + if (ret) {
>>>>> + dev_warn(&pdev->dev, "no CEC notifier available\n");
>>>>> + cec_caps |= CEC_CAP_PHYS_ADDR;
>>>>
>>>> Can this happen? What hardware has this? I am strongly opposed to CEC drivers
>>>> using this capability unless there is no other option. It's a pain for userspace.
>>>
>>> It's in case an HW having a CEC capable FW but not in the cec_dmi_match_table, in this case
>>> it won't fail but still enable the CEC interface without a notifier.
>>
>> I don't think that's a good idea. CAP_PHYS_ADDR should *only* be used in situations
>> where it is truly impossible to tell which output is connected to the CEC adapter.
>> That's the case with e.g. USB CEC dongles where you have no idea how the user
>> connected the HDMI cables.
>>
>> But I assume that in this case it just means that the cec_dmi_match_table needs
>> to be updated, i.e. it is a driver bug.
>
> Yep, maybe a dev_warn should be added to notify this bug ?

Yes, a dev_warn and then return -ENODEV.

>
>>
>> Another thing: this driver assumes that there is only one CEC adapter for only
>> one HDMI output. But what if there are more HDMI outputs? Will there be one
>> CEC adapter for each output? Or does the hardware have no provisions for that?
>
> The current EC interface only exposes a single CEC interface for now, there is no
> plan yet for multiple HDMI outputs handling.
>
>>
>> Something should be mentioned about this in a comment.
>
> Ok

Thanks!

Hans

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