[PATCH v2 4/4] drm/vc4: Restrict active CTM to one CRTC

[Stefan Schake]

Hey Daniel,

On Sun, Mar 25, 2018 at 10:01 AM, Daniel Stone <daniel at fooishbar.org> wrote:
> Hi Stefan,
>
> On 25 March 2018 at 02:52, Stefan Schake <stschake at gmail.com> wrote:
>> +static int vc4_crtc_get_ctm_fifo(struct vc4_dev *vc4)
>> +{
>> +       return VC4_GET_FIELD(HVS_READ(SCALER_OLEDOFFS),
>> +                            SCALER_OLEDOFFS_DISPFIFO);
>> +}
>
> This needs to be managed as a global resource through atomic state
> objects, rather than checking the current hardware state.

Do you mean as a property or some such that is accessible to userland
or merely that this could be raced?

I haven't had much luck finding examples for resources shared between CRTCs
in the current tree. My understanding here was that if userland commits
on CRTC B after a check-only on A, we are no longer bound by the earlier
result for the check-only. Otherwise, I would have to already commit my
CTM block to one CRTC at check (possibly check only) time.

Thanks,
Stefan