Attachment 130986 Details for Bug 100755 – scale down only link m/n

[patch] scale down only link m/n

0001-drm-i915-Do-not-scale-down-data-m_n.patch (text/plain), 1.72 KB, created by Dhinakaran Pandiyan on 2017-04-23 00:38:47 UTC

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Creator: Dhinakaran Pandiyan

Created: 2017-04-23 00:38:47 UTC

Size: 1.72 KB

patch

obsolete

>From 177f479c729dbe4ae05461242e94a410c9581c86 Mon Sep 17 00:00:00 2001
>From: Dhinakaran Pandiyan <dhnkrn@gmail.com>
>Date: Sat, 22 Apr 2017 17:31:57 -0700
>Subject: [PATCH] drm/i915: Do not scale down data m_n
>
>Signed-off-by: Dhinakaran Pandiyan <dhnkrn@gmail.com>
>---
> drivers/gpu/drm/i915/intel_display.c | 14 ++++++++++----
> 1 file changed, 10 insertions(+), 4 deletions(-)
>
>diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>index 85b9e2f5..2ec0cd0 100644
>--- a/drivers/gpu/drm/i915/intel_display.c
>+++ b/drivers/gpu/drm/i915/intel_display.c
>@@ -6276,6 +6276,14 @@ intel_reduce_m_n_ratio(uint32_t *num, uint32_t *den)
> static void compute_m_n(unsigned int m, unsigned int n,
> 			uint32_t *ret_m, uint32_t *ret_n)
> {
>+	*ret_n = min_t(unsigned int, roundup_pow_of_two(n), DATA_LINK_N_MAX);
>+	*ret_m = div_u64((uint64_t) m * *ret_n, n);
>+	intel_reduce_m_n_ratio(ret_m, ret_n);
>+}
>+
>+static void compute_scaled_m_n(unsigned int m, unsigned int n,
>+			uint32_t *ret_m, uint32_t *ret_n)
>+{
> 	/*
> 	 * Reduce M/N as much as possible without loss in precision. Several DP
> 	 * dongles in particular seem to be fussy about too large *link* M/N
>@@ -6287,9 +6295,7 @@ static void compute_m_n(unsigned int m, unsigned int n,
> 		n >>= 1;
> 	}
> 
>-	*ret_n = min_t(unsigned int, roundup_pow_of_two(n), DATA_LINK_N_MAX);
>-	*ret_m = div_u64((uint64_t) m * *ret_n, n);
>-	intel_reduce_m_n_ratio(ret_m, ret_n);
>+	compute_m_n(m, n, ret_m, ret_n);
> }
> 
> void
>@@ -6303,7 +6309,7 @@ intel_link_compute_m_n(int bits_per_pixel, int nlanes,
> 		    link_clock * nlanes * 8,
> 		    &m_n->gmch_m, &m_n->gmch_n);
> 
>-	compute_m_n(pixel_clock, link_clock,
>+	compute_scaled_m_n(pixel_clock, link_clock,
> 		    &m_n->link_m, &m_n->link_n);
> }
> 
>-- 
>2.7.4
>

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Attachments on bug 100755: 130972 | 130973 | 130979 | 130986 | 131053 | 131054 | 131098

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