Re: [PATCH 2/3 v8] mailbox: Enable BCM2835 mailbox support

[Eric Anholt]

Noralf TrÃnnes <noralf@xxxxxxxxxxx> writes:

> Den 05.05.2015 22:27, skrev Eric Anholt:
>> From: Lubomir Rintel <lkundrak@xxxxx>
>>
>> This mailbox driver provides a single mailbox channel to write 32-bit
>> values to the VPU and get a 32-bit response.  The Raspberry Pi
>> firmware uses this mailbox channel to implement firmware calls, while
>> Roku 2 (despite being derived from the same firmware tree) doesn't.
>>
>> The driver was originally submitted by Lubomir, based on the
>> out-of-tree 2708 mailbox driver.  Eric Anholt fixed it up for
>> upstreaming, with the major functional change being that it now has no
>> notion of multiple channels (since that is a firmware-dependent
>> concept) and instead the raspberrypi-firmware driver will do that
>> bit-twiddling in its own messages.
> ...
>> +static struct platform_driver bcm2835_mbox_driver = {
>> +	.driver = {
>> +		.name = "bcm2835-mbox",
>> +		.owner = THIS_MODULE,
>> +		.of_match_table = bcm2835_mbox_of_match,
>> +	},
>> +	.probe		= bcm2835_mbox_probe,
>> +	.remove		= bcm2835_mbox_remove,
>> +};
>> +module_platform_driver(bcm2835_mbox_driver);
>
> I have tested this driver and the firmware driver booting directly
> from the VideoCore bootloader (no uboot).
> The mailbox driver loads too late to turn on USB power:

Yeah, I have a patch on my branches that returns -EPROBE_DEFER when
trying to get a power domain and not finding the provider.  It was
rejected by the maintainers in favor of a proposed solution whose
description I didn't quite follow.

> This silences the warning:
> struct raspberrypi_power_domain raspberrypi_power_domain_usb = {
>      .base = {
>          .power_on_latency_ns = 600000000,

Oh, nice.  Thanks!

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