From: swarren@wwwdotorg•org (Stephen Warren)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 2/3] ARM: bcm2835: Add the Raspberry Pi firmware driver
Date: Wed, 29 Apr 2015 17:47:46 -0600 [thread overview]
Message-ID: <55416DA2.5040902@wwwdotorg.org> (raw)
In-Reply-To: <87oam6q0v1.fsf@eliezer.anholt.net>
On 04/29/15 11:51, Eric Anholt wrote:
> Stephen Warren <swarren@wwwdotorg•org> writes:
>
>> On 04/27/2015 05:14 PM, Eric Anholt wrote:
>>> This gives us a function for making mailbox property channel requests
>>> of the firmware, and uses it to control the 3 power domains provided
>>> by the firmware.
>>
>>> diff --git a/arch/arm/mach-bcm/raspberrypi-firmware.c b/arch/arm/mach-bcm/raspberrypi-firmware.c
>>
>>> +/*
>>> + * Submits a set of concatenated tags to the VPU firmware through the
>>> + * mailbox property interface.
>>> + *
>>> + * The buffer header and the ending tag are added by this function and
>>> + * don't need to be supplied, just the actual tags for your operation.
>>> + * See struct raspberrypi_firmware_property_tag_header for the per-tag structure.
>>> + */
>>> +int raspberrypi_firmware_property(void *data, size_t tag_size)
>>> +{
>>> + size_t size = tag_size + 12;
>>> + u32 *buf;
>>> + dma_addr_t bus_addr;
>>> + int ret = 0;
>>> +
>>> + if (!firmware)
>>> + return -EPROBE_DEFER;
>>
>> I think it'd make more sense if the clients looked up the firmware
>> driver via phandle at their probe time. This would mean:
>>
>> * No need for global "firmware", since clients could pass the firmware
>> driver handle into this function.
>>
>> * Clients resolve deferred probe at their probe time. That way, they
>> won't register themselves with subsystems asserting they can provide
>> services, but find out they can't yet provide the service at that time.
>
> The one client so far (vc4) was resolving deferred probe at its probe
> time, but not taking a reference on the firmware driver. I figure I'll
> have it do the phandle lookup and refcount -- do you still want the
> struct platform_device passed in here? If we de-global firmware, it's
> going to mean some faffing in the power domain side of things to find
> the device again, it seems.
I think I'd expect the API in the firmware driver to require the client
to pass the client DT node pointer plus a property name, and do all the
lookup itself. That's what most DT resource lookup APIs in the kernel do
now.
next prev parent reply other threads:[~2015-04-29 23:47 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-27 23:14 [PATCH 0/3] Raspberry Pi firmware driver Eric Anholt
2015-04-27 23:14 ` [PATCH 1/3] dt/bindings: Add binding for the " Eric Anholt
2015-04-28 9:34 ` Lee Jones
2015-04-29 1:42 ` Stephen Warren
2015-04-27 23:14 ` [PATCH 2/3] ARM: bcm2835: Add " Eric Anholt
2015-04-28 7:56 ` Arnd Bergmann
2015-04-28 20:07 ` Eric Anholt
2015-04-28 9:27 ` Lee Jones
2015-04-28 9:28 ` Lee Jones
2015-04-29 1:58 ` Stephen Warren
2015-04-29 2:14 ` Jassi Brar
2015-04-29 2:56 ` Jassi Brar
2015-04-29 17:51 ` Eric Anholt
2015-04-29 23:47 ` Stephen Warren [this message]
2015-05-12 17:46 ` Eric Anholt
2015-05-12 22:08 ` Stephen Warren
2015-05-13 0:38 ` Eric Anholt
2015-05-13 18:28 ` Stephen Warren
2015-04-27 23:14 ` [PATCH 3/3] ARM: bcm2835: Add the necessary firmware driver information to the DT Eric Anholt
2015-04-28 9:33 ` Lee Jones
2015-04-29 1:44 ` Stephen Warren
2015-04-29 16:29 ` Eric Anholt
2015-04-29 23:43 ` Stephen Warren
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