linux-kernel - [PATCH v2] drm/msm/dp: Only create debugfs for PRIMARY minor

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Message-Id: <20211217002026.2304973-1-bjorn.andersson@linaro.org>
Date:   Thu, 16 Dec 2021 16:20:26 -0800
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Rob Clark <robdclark@...il.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, linux-arm-msm@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2] drm/msm/dp: Only create debugfs for PRIMARY minor

dpu_kms_debugfs_init() is invoked for each minor being registered. Most
of the files created are unrelated to the minor, so there's no reason to
present them per minor.
The exception to this is the DisplayPort code, which ends up invoking
dp_debug_get() for each minor, each time associate the allocated object
with dp->debug.

As such dp_debug will create debugfs files in both the PRIMARY and the
RENDER minor's debugfs directory, but only the last reference will be
remembered.

The only use of this reference today is in the cleanup path in
dp_display_deinit_sub_modules() and the dp_debug_private object does
outlive the debugfs entries in either case, so there doesn't seem to be
any adverse effects of this, but per the code the current behavior is
unexpected, so change it to only create debugfs files for the PRIMARY
minor.

Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
---

Changes since v1:
- Moved the check up from msm_dp_debugfs_init() to dpu_kms_debugfs_init()

 drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
index 2ee70072a1b4..a54f7d373f14 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
@@ -193,6 +193,10 @@ static int dpu_kms_debugfs_init(struct msm_kms *kms, struct drm_minor *minor)
 	if (!p)
 		return -EINVAL;

+	/* Only create one set of debugfs per DP instance */
+	if (minor->type != DRM_MINOR_PRIMARY)
+		return 0;
+
 	dev = dpu_kms->dev;
 	priv = dev->dev_private;

-- 
2.33.1