linux-kernel - [PATCH 5.15 240/279] drm/amd/display: Limit max DSC target bpp for specific monitors

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Message-Id: <20211124115727.024026560@linuxfoundation.org>
Date:   Wed, 24 Nov 2021 12:58:47 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
        Qingqing Zhuo <qingqing.zhuo@....com>,
        Roman Li <Roman.Li@....com>,
        Daniel Wheeler <Daniel.Wheeler@....com>,
        Alex Deucher <alexander.deucher@....com>
Subject: [PATCH 5.15 240/279] drm/amd/display: Limit max DSC target bpp for specific monitors

From: Roman Li <Roman.Li@....com>

commit 55eea8ef98641f6e1e1c202bd3a49a57c1dd4059 upstream.

[Why]
Some monitors exhibit corruption at 16bpp DSC.

[How]
- Add helpers for patching edid caps.
- Use it for limiting DSC target bitrate to 15bpp for known monitors

Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@....com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@....com>
Signed-off-by: Roman Li <Roman.Li@....com>
Cc: stable@...r.kernel.org
Tested-by: Daniel Wheeler <Daniel.Wheeler@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c |   35 ++++++++++++++
 1 file changed, 35 insertions(+)

--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
@@ -40,6 +40,39 @@
 
 #include "dm_helpers.h"
 
+struct monitor_patch_info {
+	unsigned int manufacturer_id;
+	unsigned int product_id;
+	void (*patch_func)(struct dc_edid_caps *edid_caps, unsigned int param);
+	unsigned int patch_param;
+};
+static void set_max_dsc_bpp_limit(struct dc_edid_caps *edid_caps, unsigned int param);
+
+static const struct monitor_patch_info monitor_patch_table[] = {
+{0x6D1E, 0x5BBF, set_max_dsc_bpp_limit, 15},
+{0x6D1E, 0x5B9A, set_max_dsc_bpp_limit, 15},
+};
+
+static void set_max_dsc_bpp_limit(struct dc_edid_caps *edid_caps, unsigned int param)
+{
+	if (edid_caps)
+		edid_caps->panel_patch.max_dsc_target_bpp_limit = param;
+}
+
+static int amdgpu_dm_patch_edid_caps(struct dc_edid_caps *edid_caps)
+{
+	int i, ret = 0;
+
+	for (i = 0; i < ARRAY_SIZE(monitor_patch_table); i++)
+		if ((edid_caps->manufacturer_id == monitor_patch_table[i].manufacturer_id)
+			&&  (edid_caps->product_id == monitor_patch_table[i].product_id)) {
+			monitor_patch_table[i].patch_func(edid_caps, monitor_patch_table[i].patch_param);
+			ret++;
+		}
+
+	return ret;
+}
+
 /* dm_helpers_parse_edid_caps
  *
  * Parse edid caps
@@ -125,6 +158,8 @@ enum dc_edid_status dm_helpers_parse_edi
 	kfree(sads);
 	kfree(sadb);
 
+	amdgpu_dm_patch_edid_caps(edid_caps);
+
 	return result;
 }