[PATCH v2 10/23] dmaengine: sdxi: Complete administrative context jump start

[Nathan Lynch via B4 Relay <devnull+nathan.lynch.amd.com@kernel.org>]

From: Nathan Lynch <nathan.lynch@amd.com>

Now that the SDXI function has been placed in active state, the admin
context can finally be started by writing its doorbell. Introduce
a sdxi_cxt_push_doorbell() helper to simplify this for callers; it
will be used in all descriptor submission paths.

Co-developed-by: Wei Huang <wei.huang2@amd.com>
Signed-off-by: Wei Huang <wei.huang2@amd.com>
Signed-off-by: Nathan Lynch <nathan.lynch@amd.com>
---
 drivers/dma/sdxi/context.h |  6 ++++++
 drivers/dma/sdxi/device.c  | 15 ++++++++++++++-
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/sdxi/context.h b/drivers/dma/sdxi/context.h
index 65b773446ba3..8dd6beb7a642 100644
--- a/drivers/dma/sdxi/context.h
+++ b/drivers/dma/sdxi/context.h
@@ -7,6 +7,7 @@
 #define DMA_SDXI_CONTEXT_H
 
 #include <linux/dma-mapping.h>
+#include <linux/io-64-nonatomic-lo-hi.h>
 #include <linux/types.h>
 
 #include "hw.h"
@@ -58,4 +59,9 @@ struct sdxi_cxt {
 
 int sdxi_admin_cxt_init(struct sdxi_dev *sdxi);
 
+static inline void sdxi_cxt_push_doorbell(struct sdxi_cxt *cxt, u64 index)
+{
+	iowrite64(index, cxt->db);
+}
+
 #endif /* DMA_SDXI_CONTEXT_H */
diff --git a/drivers/dma/sdxi/device.c b/drivers/dma/sdxi/device.c
index 204841afa5b7..8e621875b10b 100644
--- a/drivers/dma/sdxi/device.c
+++ b/drivers/dma/sdxi/device.c
@@ -262,7 +262,20 @@ static int sdxi_fn_activate(struct sdxi_dev *sdxi)
 	 * SDXI 1.0 4.1.8.9: Set MMIO_CTL0.fn_gsr to GSRV_ACTIVE and
 	 * wait for MMIO_STS0.fn_gsv to reach GSV_ACTIVE or GSV_ERROR.
 	 */
-	return sdxi_dev_start(sdxi);
+	err = sdxi_dev_start(sdxi);
+	if (err)
+		return err;
+
+	/*
+	 * SDXI 1.0 4.1.8.10.b: Start the admin context using method
+	 * #3 ("Jump Start 1") from 4.3.4 Starting A Context and
+	 * Context Signaling. We haven't queued any descriptors to the
+	 * admin context at this point, so the appropriate value for
+	 * the doorbell is 0.
+	 */
+	sdxi_cxt_push_doorbell(sdxi->admin_cxt, 0);
+
+	return 0;
 }
 
 static int sdxi_device_init(struct sdxi_dev *sdxi)

-- 
2.54.0