linux-kernel - [PATCH v7/v3 21/22] gpu: host1x: Use RESTART

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Date:   Mon, 27 Jun 2022 17:20:07 +0300
From:   Mikko Perttunen <cyndis@...si.fi>
To:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Dmitry Osipenko <digetx@...il.com>
Cc:     Mikko Perttunen <mperttunen@...dia.com>,
        Robin Murphy <robin.murphy@....com>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v7/v3 21/22] gpu: host1x: Use RESTART_W to skip timed out jobs on Tegra186+

From: Mikko Perttunen <mperttunen@...dia.com>

When MLOCK enforcement is enabled, the 0-word write currently done
is rejected by the hardware outside of an MLOCK region. As such,
on these chips, which also have the newer, more convenient RESTART_W
opcode, use that instead to skip over the timed out job.

Signed-off-by: Mikko Perttunen <mperttunen@...dia.com>
---
 drivers/gpu/host1x/cdma.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/host1x/cdma.c b/drivers/gpu/host1x/cdma.c
index 765e5aa64eb6..bb1f3c746be4 100644
--- a/drivers/gpu/host1x/cdma.c
+++ b/drivers/gpu/host1x/cdma.c
@@ -457,9 +457,24 @@ void host1x_cdma_update_sync_queue(struct host1x_cdma *cdma,
 				 * to offset 0xbad. This does nothing but
 				 * has a easily detected signature in debug
 				 * traces.
+				 *
+				 * On systems with MLOCK enforcement enabled,
+				 * the above 0 word writes would fall foul of
+				 * the enforcement. As such, in the first slot
+				 * put a RESTART_W opcode to the beginning
+				 * of the next job. We don't use this for older
+				 * chips since those only support the RESTART
+				 * opcode with inconvenient alignment requirements.
 				 */
-				mapped[2*slot+0] = 0x1bad0000;
-				mapped[2*slot+1] = 0x1bad0000;
+				if (i == 0 && host1x->info->has_wide_gather) {
+					unsigned int next_job = (job->first_get/8 + job->num_slots)
+						% HOST1X_PUSHBUFFER_SLOTS;
+					mapped[2*slot+0] = (0xd << 28) | (next_job * 2);
+					mapped[2*slot+1] = 0x0;
+				} else {
+					mapped[2*slot+0] = 0x1bad0000;
+					mapped[2*slot+1] = 0x1bad0000;
+				}
 			}
 
 			job->cancelled = true;
-- 
2.36.1