* [PATCH] drm/i915: Allow fuzzy matching in intel_compare_link_m_n
@ 2016-01-06 12:54 Maarten Lankhorst
2016-01-06 13:00 ` Kenneth Graunke
2016-01-06 13:17 ` Daniel Vetter
0 siblings, 2 replies; 3+ messages in thread
From: Maarten Lankhorst @ 2016-01-06 12:54 UTC (permalink / raw)
To: Intel Graphics Development; +Cc: Kenneth Graunke
This prevents a unnecessary modeset on a dell XPS 13 (2016).
N is always a power of 2, which means that for fuzzy matching we should
compare for inequality on the n values, then do fuzzy matching on the m
values.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Tested-by:
--
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 7afbdc45a278..aa4f1e69b92e 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -12638,19 +12638,22 @@ intel_compare_m_n(unsigned int m, unsigned int n,
BUILD_BUG_ON(DATA_LINK_M_N_MASK > INT_MAX);
- if (m > m2) {
- while (m > m2) {
+ if (n > n2) {
+ while (n > n2) {
m2 <<= 1;
n2 <<= 1;
}
- } else if (m < m2) {
- while (m < m2) {
+ } else if (n < n2) {
+ while (n < n2) {
m <<= 1;
n <<= 1;
}
}
- return m == m2 && n == n2;
+ if (n != n2)
+ return false;
+
+ return intel_fuzzy_clock_check(m, m2);
}
static bool
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^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] drm/i915: Allow fuzzy matching in intel_compare_link_m_n
2016-01-06 12:54 [PATCH] drm/i915: Allow fuzzy matching in intel_compare_link_m_n Maarten Lankhorst
@ 2016-01-06 13:00 ` Kenneth Graunke
2016-01-06 13:17 ` Daniel Vetter
1 sibling, 0 replies; 3+ messages in thread
From: Kenneth Graunke @ 2016-01-06 13:00 UTC (permalink / raw)
To: Maarten Lankhorst; +Cc: Intel Graphics Development
[-- Attachment #1.1: Type: text/plain, Size: 1203 bytes --]
On Wednesday, January 6, 2016 1:54:43 PM PST Maarten Lankhorst wrote:
> This prevents a unnecessary modeset on a dell XPS 13 (2016).
>
> N is always a power of 2, which means that for fuzzy matching we should
> compare for inequality on the n values, then do fuzzy matching on the m
> values.
>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Tested-by:
Tested-by: Kenneth Graunke <kenneth@whitecape.org>
> --
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/
intel_display.c
> index 7afbdc45a278..aa4f1e69b92e 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -12638,19 +12638,22 @@ intel_compare_m_n(unsigned int m, unsigned int n,
>
> BUILD_BUG_ON(DATA_LINK_M_N_MASK > INT_MAX);
>
> - if (m > m2) {
> - while (m > m2) {
> + if (n > n2) {
> + while (n > n2) {
> m2 <<= 1;
> n2 <<= 1;
> }
> - } else if (m < m2) {
> - while (m < m2) {
> + } else if (n < n2) {
> + while (n < n2) {
> m <<= 1;
> n <<= 1;
> }
> }
>
> - return m == m2 && n == n2;
> + if (n != n2)
> + return false;
> +
> + return intel_fuzzy_clock_check(m, m2);
> }
>
> static bool
>
>
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] drm/i915: Allow fuzzy matching in intel_compare_link_m_n
2016-01-06 12:54 [PATCH] drm/i915: Allow fuzzy matching in intel_compare_link_m_n Maarten Lankhorst
2016-01-06 13:00 ` Kenneth Graunke
@ 2016-01-06 13:17 ` Daniel Vetter
1 sibling, 0 replies; 3+ messages in thread
From: Daniel Vetter @ 2016-01-06 13:17 UTC (permalink / raw)
To: Maarten Lankhorst; +Cc: Intel Graphics Development, Kenneth Graunke
On Wed, Jan 06, 2016 at 01:54:43PM +0100, Maarten Lankhorst wrote:
> This prevents a unnecessary modeset on a dell XPS 13 (2016).
>
> N is always a power of 2, which means that for fuzzy matching we should
> compare for inequality on the n values, then do fuzzy matching on the m
> values.
>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Tested-by:
Wasn't sure about overflow risks, but as long as the value we compute
originally computed didn't overflow this should be safe.
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> --
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 7afbdc45a278..aa4f1e69b92e 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -12638,19 +12638,22 @@ intel_compare_m_n(unsigned int m, unsigned int n,
>
> BUILD_BUG_ON(DATA_LINK_M_N_MASK > INT_MAX);
>
> - if (m > m2) {
> - while (m > m2) {
> + if (n > n2) {
> + while (n > n2) {
> m2 <<= 1;
> n2 <<= 1;
> }
> - } else if (m < m2) {
> - while (m < m2) {
> + } else if (n < n2) {
> + while (n < n2) {
> m <<= 1;
> n <<= 1;
> }
> }
>
> - return m == m2 && n == n2;
> + if (n != n2)
> + return false;
> +
> + return intel_fuzzy_clock_check(m, m2);
> }
>
> static bool
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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2016-01-06 12:54 [PATCH] drm/i915: Allow fuzzy matching in intel_compare_link_m_n Maarten Lankhorst
2016-01-06 13:00 ` Kenneth Graunke
2016-01-06 13:17 ` Daniel Vetter
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