From: Sean Anderson <sean.anderson@linux.dev>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
Maxime Ripard <mripard@kernel.org>,
Thomas Zimmermann <tzimmermann@suse.de>,
dri-devel@lists.freedesktop.org
Cc: linux-arm-kernel@lists.infradead.org,
David Airlie <airlied@gmail.com>,
linux-kernel@vger.kernel.org, Daniel Vetter <daniel@ffwll.ch>,
Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>,
Michal Simek <michal.simek@amd.com>,
Sean Anderson <sean.anderson@linux.dev>
Subject: [PATCH v5 04/10] drm: zynqmp_dp: Add locking
Date: Fri, 3 May 2024 15:29:16 -0400 [thread overview]
Message-ID: <20240503192922.2172314-5-sean.anderson@linux.dev> (raw)
In-Reply-To: <20240503192922.2172314-1-sean.anderson@linux.dev>
Add some locking to prevent the IRQ/workers/bridge API calls from stepping
on each other's toes. This lock protects:
- Non-atomic registers configuring the link. That is, everything but the
IRQ registers (since these are accessed in an atomic fashion), and the DP
AUX registers (since these don't affect the link). We also access AUX
while holding this lock, so it would be very tricky to support.
- Link configuration. This is effectively everything in zynqmp_dp which
isn't read-only after probe time. So from next_bridge onward.
This lock is designed to protect configuration changes so we don't have to
do anything tricky. Configuration should never be in the hot path, so I'm
not worried about performance.
Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
---
(no changes since v2)
Changes in v2:
- Split off the HPD IRQ work into another commit
- Expand the commit message
drivers/gpu/drm/xlnx/zynqmp_dp.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
index 129beac4c073..abfccd8bb5a7 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
@@ -280,6 +280,7 @@ struct zynqmp_dp_config {
* @dpsub: Display subsystem
* @iomem: device I/O memory for register access
* @reset: reset controller
+ * @lock: Mutex protecting this struct and register access (but not AUX)
* @irq: irq
* @bridge: DRM bridge for the DP encoder
* @next_bridge: The downstream bridge
@@ -294,11 +295,16 @@ struct zynqmp_dp_config {
* @link_config: common link configuration between IP core and sink device
* @mode: current mode between IP core and sink device
* @train_set: set of training data
+ *
+ * @lock covers the link configuration in this struct and the device's
+ * registers. It does not cover @aux. It is not strictly required for any of
+ * the members which are only modified at probe/remove time (e.g. @dev).
*/
struct zynqmp_dp {
struct drm_dp_aux aux;
struct drm_bridge bridge;
struct work_struct hpd_work;
+ struct mutex lock;
struct drm_bridge *next_bridge;
struct device *dev;
@@ -1386,8 +1392,10 @@ zynqmp_dp_bridge_mode_valid(struct drm_bridge *bridge,
}
/* Check with link rate and lane count */
+ mutex_lock(&dp->lock);
rate = zynqmp_dp_max_rate(dp->link_config.max_rate,
dp->link_config.max_lanes, dp->config.bpp);
+ mutex_unlock(&dp->lock);
if (mode->clock > rate) {
dev_dbg(dp->dev, "filtered mode %s for high pixel rate\n",
mode->name);
@@ -1414,6 +1422,7 @@ static void zynqmp_dp_bridge_atomic_enable(struct drm_bridge *bridge,
pm_runtime_get_sync(dp->dev);
+ mutex_lock(&dp->lock);
zynqmp_dp_disp_enable(dp, old_bridge_state);
/*
@@ -1474,6 +1483,7 @@ static void zynqmp_dp_bridge_atomic_enable(struct drm_bridge *bridge,
zynqmp_dp_write(dp, ZYNQMP_DP_SOFTWARE_RESET,
ZYNQMP_DP_SOFTWARE_RESET_ALL);
zynqmp_dp_write(dp, ZYNQMP_DP_MAIN_STREAM_ENABLE, 1);
+ mutex_unlock(&dp->lock);
}
static void zynqmp_dp_bridge_atomic_disable(struct drm_bridge *bridge,
@@ -1481,6 +1491,7 @@ static void zynqmp_dp_bridge_atomic_disable(struct drm_bridge *bridge,
{
struct zynqmp_dp *dp = bridge_to_dp(bridge);
+ mutex_lock(&dp->lock);
dp->enabled = false;
cancel_work(&dp->hpd_work);
zynqmp_dp_write(dp, ZYNQMP_DP_MAIN_STREAM_ENABLE, 0);
@@ -1491,6 +1502,7 @@ static void zynqmp_dp_bridge_atomic_disable(struct drm_bridge *bridge,
zynqmp_dp_write(dp, ZYNQMP_DP_TX_AUDIO_CONTROL, 0);
zynqmp_dp_disp_disable(dp, old_bridge_state);
+ mutex_unlock(&dp->lock);
pm_runtime_put_sync(dp->dev);
}
@@ -1533,6 +1545,8 @@ static enum drm_connector_status zynqmp_dp_bridge_detect(struct drm_bridge *brid
u32 state, i;
int ret;
+ mutex_lock(&dp->lock);
+
/*
* This is from heuristic. It takes some delay (ex, 100 ~ 500 msec) to
* get the HPD signal with some monitors.
@@ -1560,11 +1574,13 @@ static enum drm_connector_status zynqmp_dp_bridge_detect(struct drm_bridge *brid
dp->num_lanes);
dp->status = connector_status_connected;
+ mutex_unlock(&dp->lock);
return connector_status_connected;
}
disconnected:
dp->status = connector_status_disconnected;
+ mutex_unlock(&dp->lock);
return connector_status_disconnected;
}
@@ -1725,6 +1741,7 @@ int zynqmp_dp_probe(struct zynqmp_dpsub *dpsub)
dp->dev = &pdev->dev;
dp->dpsub = dpsub;
dp->status = connector_status_disconnected;
+ mutex_init(&dp->lock);
INIT_WORK(&dp->hpd_work, zynqmp_dp_hpd_work_func);
@@ -1838,4 +1855,5 @@ void zynqmp_dp_remove(struct zynqmp_dpsub *dpsub)
zynqmp_dp_phy_exit(dp);
zynqmp_dp_reset(dp, true);
+ mutex_destroy(&dp->lock);
}
--
2.35.1.1320.gc452695387.dirty
next prev parent reply other threads:[~2024-05-03 19:29 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-03 19:29 [PATCH v5 00/10] drm: zynqmp_dp: IRQ cleanups and debugfs support Sean Anderson
2024-05-03 19:29 ` [PATCH v5 01/10] drm: zynqmp_kms: Fix AUX bus not getting unregistered Sean Anderson
2024-05-03 19:29 ` [PATCH v5 02/10] drm: zynqmp_dp: Rearrange zynqmp_dp for better padding Sean Anderson
2024-05-03 19:29 ` [PATCH v5 03/10] drm: zynqmp_dp: Don't delay work Sean Anderson
2024-05-03 19:29 ` Sean Anderson [this message]
2024-05-03 19:29 ` [PATCH v5 05/10] drm: zynqmp_dp: Don't retrain the link in our IRQ Sean Anderson
2024-05-03 19:29 ` [PATCH v5 06/10] drm: zynqmp_dp: Convert to a hard IRQ Sean Anderson
2024-05-03 19:29 ` [PATCH v5 07/10] drm: zynqmp_dp: Use AUX IRQs instead of polling Sean Anderson
2024-05-03 19:29 ` [PATCH v5 08/10] drm: zynqmp_dp: Split off several helper functions Sean Anderson
2024-05-03 19:29 ` [PATCH v5 09/10] drm: zynqmp_dp: Take dp->lock in zynqmp_dp_hpd_work_func Sean Anderson
2024-05-03 19:29 ` [PATCH v5 10/10] drm: zynqmp_dp: Add debugfs interface for compliance testing Sean Anderson
2024-05-31 16:27 ` [PATCH v5 00/10] drm: zynqmp_dp: IRQ cleanups and debugfs support Sean Anderson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240503192922.2172314-5-sean.anderson@linux.dev \
--to=sean.anderson@linux.dev \
--cc=airlied@gmail.com \
--cc=daniel@ffwll.ch \
--cc=dri-devel@lists.freedesktop.org \
--cc=laurent.pinchart@ideasonboard.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=maarten.lankhorst@linux.intel.com \
--cc=michal.simek@amd.com \
--cc=mripard@kernel.org \
--cc=tomi.valkeinen@ideasonboard.com \
--cc=tzimmermann@suse.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).