linux-kernel - Re: [PATCH 2/5] cxl: Rename CXL_DECODER

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Message-ID: <67118dcd2ba4a_3f14294fe@dwillia2-xfh.jf.intel.com.notmuch>
Date: Thu, 17 Oct 2024 15:21:01 -0700
From: Dan Williams <dan.j.williams@...el.com>
To: Huang Ying <ying.huang@...el.com>, Dan Williams
	<dan.j.williams@...el.com>, Dave Jiang <dave.jiang@...el.com>
CC: <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Huang Ying
	<ying.huang@...el.com>, Davidlohr Bueso <dave@...olabs.net>, Gregory Price
	<gourry@...rry.net>, Jonathan Cameron <jonathan.cameron@...wei.com>, "Alison
 Schofield" <alison.schofield@...el.com>, Vishal Verma
	<vishal.l.verma@...el.com>, Ira Weiny <ira.weiny@...el.com>, Alejandro Lucero
	<alucerop@....com>, Ben Cheatham <benjamin.cheatham@....com>
Subject: Re: [PATCH 2/5] cxl: Rename CXL_DECODER_HOSTONLYMEM/DEVMEM

Huang Ying wrote:
> Previously, CXL type3 devices (memory expanders) use host only
> coherence (HDM-H), while CXL type2 devices (accelerators) use dev
> coherence (HDM-D).  So the name of the target device type of a cxl
> decoder is CXL_DECODER_HOSTONLYMEM for type3 devices and
> CXL_DECODER_DEVMEM for type2 devices.  However, this isn't true
> anymore.  CXL type3 devices can use dev coherence + back
> invalidation (HDM-DB) too.
> 
> To avoid confusion between the device type and coherence, the patch
> renames CXL_DECODER_HOSTONLYMEM/DEVMEM to CXL_DECODER_EXPANDER/ACCEL.

This does not look like an improvement to me. Type-3 devices that
support back-invalidate are DEVMEM devices. The device plays a role in
the coherence. 

Your explanation is the reverse of this commit:

5aa39a9165cf cxl/port: Rename CXL_DECODER_{EXPANDER, ACCELERATOR} => {HOSTONLYMEM, DEVMEM}

...so I am confused what motivated this rename?