linux-kernel - [PATCH v3 7/9] drm/tegra: falcon: Set DMACTX field on DMA transactions

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Message-Id: <20220218113952.3077606-8-mperttunen@nvidia.com>
Date:   Fri, 18 Feb 2022 13:39:50 +0200
From:   Mikko Perttunen <mperttunen@...dia.com>
To:     thierry.reding@...il.com, jonathanh@...dia.com, joro@...tes.org,
        will@...nel.org, robh+dt@...nel.org, robin.murphy@....com
Cc:     linux-tegra@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Mikko Perttunen <mperttunen@...dia.com>
Subject: [PATCH v3 7/9] drm/tegra: falcon: Set DMACTX field on DMA transactions

The DMACTX field determines which context, as specified in the
TRANSCFG register, is used. While during boot it doesn't matter
which is used, later on it matters and this value is reused by
the firmware.

Signed-off-by: Mikko Perttunen <mperttunen@...dia.com>
---
 drivers/gpu/drm/tegra/falcon.c | 8 ++++++++
 drivers/gpu/drm/tegra/falcon.h | 1 +
 2 files changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/tegra/falcon.c b/drivers/gpu/drm/tegra/falcon.c
index 223ab2ceb7e6..8bdb72f08f58 100644
--- a/drivers/gpu/drm/tegra/falcon.c
+++ b/drivers/gpu/drm/tegra/falcon.c
@@ -48,6 +48,14 @@ static int falcon_copy_chunk(struct falcon *falcon,
 	if (target == FALCON_MEMORY_IMEM)
 		cmd |= FALCON_DMATRFCMD_IMEM;
 
+	/*
+	 * Use second DMA context (i.e. the one for firmware). Strictly
+	 * speaking, at this point both DMA contexts point to the firmware
+	 * stream ID, but this register's value will be reused by the firmware
+	 * for later DMA transactions, so we need to use the correct value.
+	 */
+	cmd |= FALCON_DMATRFCMD_DMACTX(1);
+
 	falcon_writel(falcon, offset, FALCON_DMATRFMOFFS);
 	falcon_writel(falcon, base, FALCON_DMATRFFBOFFS);
 	falcon_writel(falcon, cmd, FALCON_DMATRFCMD);
diff --git a/drivers/gpu/drm/tegra/falcon.h b/drivers/gpu/drm/tegra/falcon.h
index c56ee32d92ee..1955cf11a8a6 100644
--- a/drivers/gpu/drm/tegra/falcon.h
+++ b/drivers/gpu/drm/tegra/falcon.h
@@ -50,6 +50,7 @@
 #define FALCON_DMATRFCMD_IDLE			(1 << 1)
 #define FALCON_DMATRFCMD_IMEM			(1 << 4)
 #define FALCON_DMATRFCMD_SIZE_256B		(6 << 8)
+#define FALCON_DMATRFCMD_DMACTX(v)		(((v) & 0x7) << 12)
 
 #define FALCON_DMATRFFBOFFS			0x0000111c
 
-- 
2.35.0