linux-kernel - [PATCH 5/7] drm/amdgpu: Don't retry 7 times in amdgpu_atombios_dp_get

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri,  5 Aug 2016 20:30:37 -0400
From:	Lyude <cpaul@...hat.com>
To:	dri-devel@...ts.freedesktop.org, amd-gfx@...ts.freedesktop.org,
	xorg-driver-ati@...ts.freedesktop.org
Cc:	Lyude <cpaul@...hat.com>, Alex Deucher <alexander.deucher@....com>,
	Christian König <christian.koenig@....com>,
	David Airlie <airlied@...ux.ie>,
	Tom St Denis <tom.stdenis@....com>,
	Harry Wentland <harry.wentland@....com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 5/7] drm/amdgpu: Don't retry 7 times in amdgpu_atombios_dp_get_dpcd()

When this code was written, we didn't retry DP aux transactions on any
error, which required retrying important transactions like this in
individual drivers. Since that's no longer the case, retrying here is
not necessary. As well, we retry any aux transaction on any error 32
times. 7 * 32 = 224, which means this loop causes us to retry grabbing
the dpcd 224 times. This is definitely far more then we actually need to
do.

Signed-off-by: Lyude <cpaul@...hat.com>
---
 drivers/gpu/drm/amd/amdgpu/atombios_dp.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/atombios_dp.c b/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
index 166dc7b..f81068b 100644
--- a/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
+++ b/drivers/gpu/drm/amd/amdgpu/atombios_dp.c
@@ -338,22 +338,21 @@ int amdgpu_atombios_dp_get_dpcd(struct amdgpu_connector *amdgpu_connector)
 {
 	struct amdgpu_connector_atom_dig *dig_connector = amdgpu_connector->con_priv;
 	u8 msg[DP_DPCD_SIZE];
-	int ret, i;
+	int ret;
 
-	for (i = 0; i < 7; i++) {
-		ret = drm_dp_dpcd_read(&amdgpu_connector->ddc_bus->aux, DP_DPCD_REV, msg,
-				       DP_DPCD_SIZE);
-		if (ret == DP_DPCD_SIZE) {
-			memcpy(dig_connector->dpcd, msg, DP_DPCD_SIZE);
+	ret = drm_dp_dpcd_read(&amdgpu_connector->ddc_bus->aux, DP_DPCD_REV,
+			       msg, DP_DPCD_SIZE);
+	if (ret == DP_DPCD_SIZE) {
+		memcpy(dig_connector->dpcd, msg, DP_DPCD_SIZE);
 
-			DRM_DEBUG_KMS("DPCD: %*ph\n", (int)sizeof(dig_connector->dpcd),
-				      dig_connector->dpcd);
+		DRM_DEBUG_KMS("DPCD: %*ph\n", (int)sizeof(dig_connector->dpcd),
+			      dig_connector->dpcd);
 
-			amdgpu_atombios_dp_probe_oui(amdgpu_connector);
+		amdgpu_atombios_dp_probe_oui(amdgpu_connector);
 
-			return 0;
-		}
+		return 0;
 	}
+
 	dig_connector->dpcd[0] = 0;
 	return -EINVAL;
 }
-- 
2.7.4