[4.2.y-ckt stable] Patch "drm/radeon: Add a common function for DFS handling" has been added to the 4.2.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    drm/radeon: Add a common function for DFS handling

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt4.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From f49c85185f2e5c16965a035e971bbbad275e95b3 Mon Sep 17 00:00:00 2001
From: Slava Grigorev <slava.grigorev at amd.com>
Date: Tue, 26 Jan 2016 16:56:25 -0500
Subject: drm/radeon: Add a common function for DFS handling
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

commit a64c9dab1c4d05c87ec8a1cb9b48915816462143 upstream.

Move encoding of DFS (digital frequency synthesizer) divider into a
separate function and improve calculation precision.

Signed-off-by: Slava Grigorev <slava.grigorev at amd.com>
Reviewed-by: Alex Deucher <alexander.deucher at amd.com>
Reviewed-by: Christian König <christian.koenig at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/gpu/drm/radeon/dce6_afmt.c    | 12 ++----------
 drivers/gpu/drm/radeon/radeon_audio.c | 12 ++++++++++++
 drivers/gpu/drm/radeon/radeon_audio.h |  1 +
 3 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/radeon/dce6_afmt.c b/drivers/gpu/drm/radeon/dce6_afmt.c
index abd72ee..848b1ff 100644
--- a/drivers/gpu/drm/radeon/dce6_afmt.c
+++ b/drivers/gpu/drm/radeon/dce6_afmt.c
@@ -285,18 +285,10 @@ void dce6_dp_audio_set_dto(struct radeon_device *rdev,
 		unsigned int div = (RREG32(DENTIST_DISPCLK_CNTL) &
 			DENTIST_DPREFCLK_WDIVIDER_MASK) >>
 			DENTIST_DPREFCLK_WDIVIDER_SHIFT;
-
-		if (div < 128 && div >= 96)
-			div -= 64;
-		else if (div >= 64)
-			div = div / 2 - 16;
-		else if (div >= 8)
-			div /= 4;
-		else
-			div = 0;
+		div = radeon_audio_decode_dfs_div(div);

 		if (div)
-			clock /= div;
+			clock = clock * 100 / div;

 		WREG32(DCE8_DCCG_AUDIO_DTO1_PHASE, 24000);
 		WREG32(DCE8_DCCG_AUDIO_DTO1_MODULE, clock);
diff --git a/drivers/gpu/drm/radeon/radeon_audio.c b/drivers/gpu/drm/radeon/radeon_audio.c
index 85e1c23..b214663 100644
--- a/drivers/gpu/drm/radeon/radeon_audio.c
+++ b/drivers/gpu/drm/radeon/radeon_audio.c
@@ -775,3 +775,15 @@ void radeon_audio_dpms(struct drm_encoder *encoder, int mode)
 	if (radeon_encoder->audio && radeon_encoder->audio->dpms)
 		radeon_encoder->audio->dpms(encoder, mode == DRM_MODE_DPMS_ON);
 }
+
+unsigned int radeon_audio_decode_dfs_div(unsigned int div)
+{
+	if (div >= 8 && div < 64)
+		return (div - 8) * 25 + 200;
+	else if (div >= 64 && div < 96)
+		return (div - 64) * 50 + 1600;
+	else if (div >= 96 && div < 128)
+		return (div - 96) * 100 + 3200;
+	else
+		return 0;
+}
diff --git a/drivers/gpu/drm/radeon/radeon_audio.h b/drivers/gpu/drm/radeon/radeon_audio.h
index 059cc30..5c70cce 100644
--- a/drivers/gpu/drm/radeon/radeon_audio.h
+++ b/drivers/gpu/drm/radeon/radeon_audio.h
@@ -79,5 +79,6 @@ void radeon_audio_fini(struct radeon_device *rdev);
 void radeon_audio_mode_set(struct drm_encoder *encoder,
 	struct drm_display_mode *mode);
 void radeon_audio_dpms(struct drm_encoder *encoder, int mode);
+unsigned int radeon_audio_decode_dfs_div(unsigned int div);

 #endif
--
1.9.1