Re: [PATCH v2 06/20] drm/i915: Allow fuzzy matching in pipe_config_compare.

Maarten Lankhorst
2015-07-08T09:18:29Z

Op 08-07-15 om 11:09 schreef Daniel Vetter:
> On Wed, Jul 08, 2015 at 10:38:33AM +0200, Maarten Lankhorst wrote:
>> Op 07-07-15 om 12:11 schreef Daniel Vetter:
>>> On Tue, Jul 07, 2015 at 09:08:17AM +0200, Maarten Lankhorst wrote:
>>>> @@ -12392,27 +12379,124 @@ static bool intel_fuzzy_clock_check(int clock1, int clock2)
>>>> base.head) \
>>>> if (mask & (1 <<(intel_crtc)->pipe))
>>>>
>>>> +
>>>> +static bool
>>>> +intel_compare_m_n(unsigned int m, unsigned int n,
>>>> + unsigned int m2, unsigned int n2)
>>>> +{
>>>> + if (m == m2 && n == n2)
>>>> + return true;
>>>> +
>>>> + if (!m || !n || !m2 || !n2)
>>>> + return false;
>>>> +
>>>> + if (m > m2) {
>>>> + while (m > m2) {
>>> I think we need to make sure we don't reduce precision by eating low bits,
>>> i.e.
>>> while (m > m2 && !(m & 1) && !(n & 1)) {
>> Could be useful, lets hope everyone rounds in the same way. :)
>>>> + m >>= 1;
>>>> + n >>= 1;
>>>> + }
>>>> + } else if (m < m2) {
>>>> + while (m < m2) {
>>>> + m2 >>= 1;
>>>> + n2 >>= 1;
>>>> + }
>>>> + }
>>>> +
>>>> + return m == m2 && n == n2;
>>>> +}
>>>> +
>>>> +static bool
>>>> +intel_compare_link_m_n(const struct intel_link_m_n *m_n,
>>>> + const struct intel_link_m_n *m2_n2)
>>> I think these need to take adjust as an agurment and check for exact match
>>> (not just matching ratio), like before.
>> I just implemented it, then remembered why I didn't.
>>
>> It will cause a failure in intel_modeset_check_state.
> That shouldn't happen. I guess the bug is that adjust doesn't live up to
> it's name and doesn't copy the current value over to the new config if
> they're compatible?
It's a compare function, I didn't want to do adjustments in it and leaving it as a multiple is harmless.
In case of gen >= 8 it might even fix itself through intel_dp_set_drrs_state.

~Maarten