From: Daniel Vetter <daniel@ffwll.ch>
To: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
Kenneth Graunke <kenneth@whitecape.org>
Subject: Re: [PATCH] drm/i915: Allow fuzzy matching in intel_compare_link_m_n
Date: Wed, 6 Jan 2016 14:17:03 +0100 [thread overview]
Message-ID: <20160106131703.GI8076@phenom.ffwll.local> (raw)
In-Reply-To: <568D0E93.304@linux.intel.com>
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
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx
prev parent reply other threads:[~2016-01-06 13:17 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
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 [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160106131703.GI8076@phenom.ffwll.local \
--to=daniel@ffwll.ch \
--cc=intel-gfx@lists.freedesktop.org \
--cc=kenneth@whitecape.org \
--cc=maarten.lankhorst@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.