From: Dave Jiang <dave.jiang@intel.com>
To: Gregory Price <gourry@gourry.net>,
"Zhijian Li (Fujitsu)" <lizhijian@fujitsu.com>
Cc: Huaisheng Ye <huaisheng.ye@intel.com>,
"Jonathan.Cameron@huawei.com" <Jonathan.Cameron@huawei.com>,
"dan.j.williams@intel.com" <dan.j.williams@intel.com>,
"pei.p.jia@intel.com" <pei.p.jia@intel.com>,
"linux-cxl@vger.kernel.org" <linux-cxl@vger.kernel.org>
Subject: Re: [RFC PATCH] cxl/core: reenable Mem_Enable bit of DVSEC control when RR decodes outside platform ranges
Date: Wed, 9 Apr 2025 08:13:48 -0700 [thread overview]
Message-ID: <43967129-86ec-4dbc-a065-11269e311fed@intel.com> (raw)
In-Reply-To: <Z_aAnzqR-UP9rmIY@gourry-fedora-PF4VCD3F>
On 4/9/25 7:13 AM, Gregory Price wrote:
> On Mon, Apr 07, 2025 at 08:31:13AM +0000, Zhijian Li (Fujitsu) wrote:
>> [1] https://lore.kernel.org/linux-cxl/20240409075846.85370-1-lizhijian@fujitsu.com/
>
> After looking at this, I see why this hasn't been fixed in QEMU.
> Basically QEMU doesn't implement the right reset mechanism.
>
> ct3_reset calls
> cxl_component_register_init_common()
> ARRAY_FIELD_DP32(reg_state, CXL_HDM_DECODER_GLOBAL_CONTROL,
> HDM_DECODER_ENABLE, 0)
>
> But it never resets MEM_ENABLE in the dvsecs.
>
> I'm not sure it's sane for Linux to be trying to handle hardware that
> doesn't itself reset correctly - and doing this fix just for QEMU seems
> a bit too far.
I agree. No need to twist Linux in a bunch for something broken on QEMU. Until there's actual hardware that does this deployed in the field, we should just leave the Linux driver as is.
>
> The correct fix here is building an accessor for the existing CXL dvsecs
> and updating it during ct3_reset.
>
> ~Gregory
next prev parent reply other threads:[~2025-04-09 15:13 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-06 11:27 [RFC PATCH] cxl/core: reenable Mem_Enable bit of DVSEC control when RR decodes outside platform ranges Huaisheng Ye
2025-04-07 8:31 ` Zhijian Li (Fujitsu)
2025-04-09 3:51 ` Ye, Huaisheng
2025-04-09 14:13 ` Gregory Price
2025-04-09 15:13 ` Dave Jiang [this message]
2025-04-15 16:21 ` Jonathan Cameron
2025-04-08 3:22 ` Gregory Price
2025-04-09 3:48 ` Ye, Huaisheng
2025-04-09 14:01 ` Gregory Price
2025-04-10 7:12 ` Ye, Huaisheng
2025-04-15 16:30 ` Jonathan Cameron
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