linux-kernel - [PATCH v2] drm/amd/display: use a more accurate check in dm_helpers_dp_read

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Message-ID: <20230310184233.284388-1-hamza.mahfooz@amd.com>
Date:   Fri, 10 Mar 2023 13:42:33 -0500
From:   Hamza Mahfooz <hamza.mahfooz@....com>
To:     <amd-gfx@...ts.freedesktop.org>
CC:     Hamza Mahfooz <hamza.mahfooz@....com>,
        Harry Wentland <harry.wentland@....com>,
        Leo Li <sunpeng.li@....com>,
        Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>, Lyude Paul <lyude@...hat.com>,
        Wayne Lin <Wayne.Lin@....com>,
        Qingqing Zhuo <qingqing.zhuo@....com>,
        Wenjing Liu <wenjing.liu@....com>,
        Sung Joon Kim <sungjoon.kim@....com>,
        <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v2] drm/amd/display: use a more accurate check in dm_helpers_dp_read_dpcd()

We should be checking if drm_dp_dpcd_read() returns the size that we are
asking it to read instead of just checking if it is greater than zero.
So, compare the return value of drm_dp_dpcd_read() to the requested
read size.

Signed-off-by: Hamza Mahfooz <hamza.mahfooz@....com>
---
v2: drop the WARN_ON().
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
index 8d598b322e5b..9c1e91c2179e 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c
@@ -511,8 +511,8 @@ bool dm_helpers_dp_read_dpcd(
 		return false;
 	}
 
-	return drm_dp_dpcd_read(&aconnector->dm_dp_aux.aux, address,
-			data, size) > 0;
+	return drm_dp_dpcd_read(&aconnector->dm_dp_aux.aux, address, data,
+				size) == size;
 }
 
 bool dm_helpers_dp_write_dpcd(
-- 
2.39.2