Re: [RESEND PATCH V11 XDMA 2/2] dmaengine: xilinx: xdma: Add user logic interrupt support

From: Lars-Peter Clausen
Date: Wed Jan 18 2023 - 11:02:26 EST


On 1/18/23 07:28, Martin Tůma wrote:
+++ b/include/linux/dma/amd_xdma.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2022, Advanced Micro Devices, Inc.
+ */
+
+#ifndef _DMAENGINE_AMD_XDMA_H
+#define _DMAENGINE_AMD_XDMA_H
+
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+
+int xdma_enable_user_irq(struct platform_device *pdev, u32 irq_num);
+void xdma_disable_user_irq(struct platform_device *pdev, u32 irq_num);
+int xdma_get_user_irq(struct platform_device *pdev, u32 user_irq_index);

who is the user of these APIs? It is not clear to me how this is to be
used...


The APIs are used by the PCIe card devices/drivers that use XDMA. Without them the "user IRQs" provided by the XDMA HW can not be used by the PCIe card drivers. If you look at the XDMA HW overview:
https://docs.xilinx.com/r/en-US/pg195-pcie-dma/Overview?tocId=O_EMX26J5IsdubL4i3XJ_w
those APIs control the "IRQ module" block.

For a linux driver using them see the mgb4 v4l2 driver:
https://patchwork.kernel.org/project/linux-media/patch/20230113172636.2590-2-tumic@xxxxxxxxxx/


Rather than custom functions this should probably be integrated with the generic IRQ framework registering a IRQ chip that provides IRQs that can be requested by the consumer.