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

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Message-ID: <85d1e660-1df4-6e84-a329-751197ef7eec@gpxsee.org>
Date:   Wed, 18 Jan 2023 16:28:12 +0100
From:   Martin Tůma <tumic@...see.org>
To:     Vinod Koul <vkoul@...nel.org>, Lizhi Hou <lizhi.hou@....com>
Cc:     dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
        max.zhen@....com, sonal.santan@....com, larry.liu@....com,
        brian.xu@....com
Subject: Re: [RESEND PATCH V11 XDMA 2/2] dmaengine: xilinx: xdma: Add user
 logic interrupt support

>> +++ 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@gpxsee.org/

M.