Patch "drm/amd/display: Implement workaround for writing to OTG_PIXEL_RATE_DIV register" has been added to the 6.1-stable tree

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This is a note to let you know that I've just added the patch titled

    drm/amd/display: Implement workaround for writing to OTG_PIXEL_RATE_DIV register

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-amd-display-implement-workaround-for-writing-to-otg_pixel_rate_div-register.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 74fa4c81aadf418341f0d073c864ea7dca730a2e Mon Sep 17 00:00:00 2001
From: Saaem Rizvi <SyedSaaem.Rizvi@xxxxxxx>
Date: Mon, 6 Mar 2023 15:10:13 -0500
Subject: drm/amd/display: Implement workaround for writing to OTG_PIXEL_RATE_DIV register

From: Saaem Rizvi <SyedSaaem.Rizvi@xxxxxxx>

commit 74fa4c81aadf418341f0d073c864ea7dca730a2e upstream.

[Why and How]
Current implementation requires FPGA builds to take a different
code path from DCN32 to write to OTG_PIXEL_RATE_DIV. Now that
we have a workaround to write to OTG_PIXEL_RATE_DIV register without
blanking display on hotplug on DCN32, we can allow the code paths for
FPGA to be exactly the same allowing for more consistent
testing.

Reviewed-by: Alvin Lee <Alvin.Lee2@xxxxxxx>
Acked-by: Qingqing Zhuo <qingqing.zhuo@xxxxxxx>
Signed-off-by: Saaem Rizvi <SyedSaaem.Rizvi@xxxxxxx>
Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: "Limonciello, Mario" <mario.limonciello@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/amd/display/dc/dcn20/dcn20_dccg.h     |    3 +-
 drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dccg.c     |   22 ++++++++++++++++++
 drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dccg.h     |    3 +-
 drivers/gpu/drm/amd/display/dc/dcn32/dcn32_hwseq.c    |    2 -
 drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource.h |    3 +-
 5 files changed, 29 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_dccg.h
+++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_dccg.h
@@ -230,7 +230,8 @@
 	type DTBCLK_P2_SRC_SEL;\
 	type DTBCLK_P2_EN;\
 	type DTBCLK_P3_SRC_SEL;\
-	type DTBCLK_P3_EN;
+	type DTBCLK_P3_EN;\
+	type DENTIST_DISPCLK_CHG_DONE;
 
 struct dccg_shift {
 	DCCG_REG_FIELD_LIST(uint8_t)
--- a/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dccg.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dccg.c
@@ -42,6 +42,20 @@
 #define DC_LOGGER \
 	dccg->ctx->logger
 
+/* This function is a workaround for writing to OTG_PIXEL_RATE_DIV
+ * without the probability of causing a DIG FIFO error.
+ */
+static void dccg32_wait_for_dentist_change_done(
+	struct dccg *dccg)
+{
+	struct dcn_dccg *dccg_dcn = TO_DCN_DCCG(dccg);
+
+	uint32_t dentist_dispclk_value = REG_READ(DENTIST_DISPCLK_CNTL);
+
+	REG_WRITE(DENTIST_DISPCLK_CNTL, dentist_dispclk_value);
+	REG_WAIT(DENTIST_DISPCLK_CNTL, DENTIST_DISPCLK_CHG_DONE, 1, 50, 2000);
+}
+
 static void dccg32_get_pixel_rate_div(
 		struct dccg *dccg,
 		uint32_t otg_inst,
@@ -110,21 +124,29 @@ static void dccg32_set_pixel_rate_div(
 		REG_UPDATE_2(OTG_PIXEL_RATE_DIV,
 				OTG0_PIXEL_RATE_DIVK1, k1,
 				OTG0_PIXEL_RATE_DIVK2, k2);
+
+		dccg32_wait_for_dentist_change_done(dccg);
 		break;
 	case 1:
 		REG_UPDATE_2(OTG_PIXEL_RATE_DIV,
 				OTG1_PIXEL_RATE_DIVK1, k1,
 				OTG1_PIXEL_RATE_DIVK2, k2);
+
+		dccg32_wait_for_dentist_change_done(dccg);
 		break;
 	case 2:
 		REG_UPDATE_2(OTG_PIXEL_RATE_DIV,
 				OTG2_PIXEL_RATE_DIVK1, k1,
 				OTG2_PIXEL_RATE_DIVK2, k2);
+
+		dccg32_wait_for_dentist_change_done(dccg);
 		break;
 	case 3:
 		REG_UPDATE_2(OTG_PIXEL_RATE_DIV,
 				OTG3_PIXEL_RATE_DIVK1, k1,
 				OTG3_PIXEL_RATE_DIVK2, k2);
+
+		dccg32_wait_for_dentist_change_done(dccg);
 		break;
 	default:
 		BREAK_TO_DEBUGGER();
--- a/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dccg.h
+++ b/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_dccg.h
@@ -147,7 +147,8 @@
 	DCCG_SF(DTBCLK_P_CNTL, DTBCLK_P3_SRC_SEL, mask_sh),\
 	DCCG_SF(DTBCLK_P_CNTL, DTBCLK_P3_EN, mask_sh),\
 	DCCG_SF(DCCG_AUDIO_DTO_SOURCE, DCCG_AUDIO_DTO_SEL, mask_sh),\
-	DCCG_SF(DCCG_AUDIO_DTO_SOURCE, DCCG_AUDIO_DTO0_SOURCE_SEL, mask_sh)
+	DCCG_SF(DCCG_AUDIO_DTO_SOURCE, DCCG_AUDIO_DTO0_SOURCE_SEL, mask_sh),\
+	DCCG_SF(DENTIST_DISPCLK_CNTL, DENTIST_DISPCLK_CHG_DONE, mask_sh)
 
 
 struct dccg *dccg32_create(
--- a/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_hwseq.c
@@ -1177,7 +1177,7 @@ unsigned int dcn32_calculate_dccg_k1_k2_
 			*k2_div = PIXEL_RATE_DIV_BY_2;
 		else
 			*k2_div = PIXEL_RATE_DIV_BY_4;
-	} else if (dc_is_dp_signal(stream->signal)) {
+	} else if (dc_is_dp_signal(stream->signal) || dc_is_virtual_signal(stream->signal)) {
 		if (two_pix_per_container) {
 			*k1_div = PIXEL_RATE_DIV_BY_1;
 			*k2_div = PIXEL_RATE_DIV_BY_2;
--- a/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource.h
+++ b/drivers/gpu/drm/amd/display/dc/dcn32/dcn32_resource.h
@@ -1272,7 +1272,8 @@ unsigned int dcn32_calc_num_avail_chans_
       DCCG_SRII(PHASE, DTBCLK_DTO, 0), DCCG_SRII(PHASE, DTBCLK_DTO, 1),        \
       DCCG_SRII(PHASE, DTBCLK_DTO, 2), DCCG_SRII(PHASE, DTBCLK_DTO, 3),        \
       SR(DCCG_AUDIO_DTBCLK_DTO_MODULO), SR(DCCG_AUDIO_DTBCLK_DTO_PHASE),       \
-      SR(OTG_PIXEL_RATE_DIV), SR(DTBCLK_P_CNTL), SR(DCCG_AUDIO_DTO_SOURCE)     \
+      SR(OTG_PIXEL_RATE_DIV), SR(DTBCLK_P_CNTL),                               \
+      SR(DCCG_AUDIO_DTO_SOURCE), SR(DENTIST_DISPCLK_CNTL)                      \
   )
 
 /* VMID */


Patches currently in stable-queue which might be from SyedSaaem.Rizvi@xxxxxxx are

queue-6.1/drm-amd-display-implement-workaround-for-writing-to-otg_pixel_rate_div-register.patch



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