[PATCH 1/3] drm/radeon: Make CIK support in Radeon conditional (v2)

[Alex Deucher]

On Mon, Apr 10, 2017 at 2:13 PM, Felix Kuehling <felix.kuehling at amd.com> wrote:
> On 17-04-09 09:28 PM, Michel Dänzer wrote:
>> On 10/04/17 09:56 AM, Michel Dänzer wrote:
>>> On 08/04/17 05:15 AM, Felix Kuehling wrote:
>>>> Advertise CIK PCI IDs only when they are not supported by amdgpu.
>>>> Use the CONFIG_DRM_AMDGPU_CIK to check so that a single option in
>>>> the kernel config keeps both drivers in sync.
>>>>
>>>> This is the simplest possible change. A more complete solution
>>>> may want to conditionally disable more CIK-specific code in the
>>>> Radeon driver.
>>>>
>>>> v2: Add CONFIG_DRM_RADEON_FORCE_CIK option
>>>>
>>>> Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
>>> I don't think this is good enough a solution.
>> To elaborate, my main objection is that people who still want to be able
>> to use the radeon driver for CIK/SI GPUs with CONFIG_DRM_AMDGPU_CIK
>> enabled have to enable the new CONFIG_DRM_RADEON_FORCE_CIK/SI option,
>> and then they're merely back to square one, in the current situation
>> where it's not clearly defined which driver will end up being used for
>> such GPUs.
>
> So what's the usage model here? I think the situation that both AMDGPU
> and Radeon support CIK is for developers only. "Normal end users" would
> never be in this situation.
>
> For developers, Christian is OK with having just a compile time option,
> and probably choosing the driver by loading the right module manually.
> You want to have a boot time kernel option.
>
> Are there any other ideas or requests, before I go spend more time on this?


In the short term, it would probably be good to just have a tri-state option:
1. only radeon
2. only amdgpu
3. both

I don't think there is a good automagic option.

Alex