linux-kernel - Re: [PATCH v2 3/8] iommu/amd: Add debugfs support to dump IOMMU Capability registers

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Message-ID: <35ff7361-f5e6-467e-b027-bb2171d49d4f@amd.com>
Date: Tue, 7 Jan 2025 11:33:16 +0530
From: "Srivastava, Dheeraj Kumar" <dheerajkumar.srivastava@....com>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: joro@...tes.org, suravee.suthikulpanit@....com, will@...nel.org,
 robin.murphy@....com, linux-kernel@...r.kernel.org, iommu@...ts.linux.dev,
 vasant.hegde@....com
Subject: Re: [PATCH v2 3/8] iommu/amd: Add debugfs support to dump IOMMU
 Capability registers

Hi,

On 11/27/2024 2:29 AM, Bjorn Helgaas wrote:
> On Wed, Nov 06, 2024 at 01:16:34PM +0530, Dheeraj Kumar Srivastava wrote:
>> IOMMU Capability registers defines capabilities of IOMMU and information
>> needed for initialising MMIO registers and device table. This is useful
>> to dump these registers for debugging IOMMU related issues.
>>
>> e.g.To get capability registers value for iommu<x>
>>    # echo "0x10" > /sys/kernel/debug/iommu/amd/iommu00/capability
>>    # cat /sys/kernel/debug/iommu/amd/iommu00/capability_dump
> 
> Same comment here.  Why does this need to be so complicated to use?
> Can't you make a single read-only file that contains all the registers
> of interest?
> 

Please do let me know your concerns and views on my comments in the 
previous patch.

With the implemented approach we do need separate files for mmio 
registers and capability registers input/output files as to understand 
if user input is mmio's offset or capability register's offset.

Thanks
Dheeraj

> Bjorn