netdev - Re: [PATCH v4 01/26] cxl: add type2 device basic support

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Message-ID: <7deb17e2-4257-1ddf-2279-32bf4f086f67@amd.com>
Date: Mon, 28 Oct 2024 09:37:13 +0000
From: Alejandro Lucero Palau <alucerop@....com>
To: Jonathan Cameron <Jonathan.Cameron@...wei.com>,
 alejandro.lucero-palau@....com
Cc: linux-cxl@...r.kernel.org, netdev@...r.kernel.org,
 dan.j.williams@...el.com, martin.habets@...inx.com, edward.cree@....com,
 davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com, edumazet@...gle.com
Subject: Re: [PATCH v4 01/26] cxl: add type2 device basic support


On 10/25/24 14:50, Jonathan Cameron wrote:
> On Thu, 17 Oct 2024 17:52:00 +0100
> <alejandro.lucero-palau@....com> wrote:
>
>> From: Alejandro Lucero <alucerop@....com>
>>
>> Differentiate Type3, aka memory expanders, from Type2, aka device
>> accelerators, with a new function for initializing cxl_dev_state.
>>
>> Create accessors to cxl_dev_state to be used by accel drivers.
>>
>> Based on previous work by Dan Williams [1]
>>
>> Link: [1] https://lore.kernel.org/linux-cxl/168592160379.1948938.12863272903570476312.stgit@dwillia2-xfh.jf.intel.com/
>> Signed-off-by: Alejandro Lucero <alucerop@....com>
>> Co-developed-by: Dan Williams <dan.j.williams@...el.com>
> Hi Alejandro,
>
> A couple of trivial comments inline on things that that would be good to tidy up.
>
>> ---
>>   drivers/cxl/core/memdev.c | 52 +++++++++++++++++++++++++++++++++++++++
>>   drivers/cxl/core/pci.c    |  1 +
>>   drivers/cxl/cxlpci.h      | 16 ------------
>>   drivers/cxl/pci.c         | 13 +++++++---
>>   include/linux/cxl/cxl.h   | 21 ++++++++++++++++
>>   include/linux/cxl/pci.h   | 23 +++++++++++++++++
>>   6 files changed, 106 insertions(+), 20 deletions(-)
>>   create mode 100644 include/linux/cxl/cxl.h
>>   create mode 100644 include/linux/cxl/pci.h
>>
>> diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
>> index 0277726afd04..94b8a7b53c92 100644
>> --- a/drivers/cxl/core/memdev.c
>> +++ b/drivers/cxl/core/memdev.c
>> +int cxl_set_resource(struct cxl_dev_state *cxlds, struct resource res,
>> +		     enum cxl_resource type)
>> +{
>> +	switch (type) {
>> +	case CXL_RES_DPA:
>> +		cxlds->dpa_res = res;
>> +		return 0;
>> +	case CXL_RES_RAM:
>> +		cxlds->ram_res = res;
>> +		return 0;
>> +	case CXL_RES_PMEM:
>> +		cxlds->pmem_res = res;
>> +		return 0;
>> +	}
>> +
>> +	dev_err(cxlds->dev, "unknown resource type (%u)\n", type);
> Given it's an enum and only enum values are ever passed to it, we should never
> get here as they are all handled above.
>
> So maybe drop?  Then if an another type is added we will get a build
> warning.


OK. I'll do that.


>> +	return -EINVAL;
>> +}
>> +EXPORT_SYMBOL_NS_GPL(cxl_set_resource, CXL);
>> +
>>   static int cxl_memdev_release_file(struct inode *inode, struct file *file)
>>   {
>>   	struct cxl_memdev *cxlmd =
>> diff --git a/include/linux/cxl/cxl.h b/include/linux/cxl/cxl.h
>> new file mode 100644
>> index 000000000000..c06ca750168f
>> --- /dev/null
>> +++ b/include/linux/cxl/cxl.h
>> @@ -0,0 +1,21 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/* Copyright(c) 2024 Advanced Micro Devices, Inc. */
>> +
>> +#ifndef __CXL_H
>> +#define __CXL_H
>> +
>> +#include <linux/device.h>
> I'd avoid this if possible and use a forwards definition for
> struct device;
> Also needed for
> struct cxl_dev_state;
> And an include needed for linux/ioport.h for the struct
> resource.


Right. And I'm adding another include later on in this patchset that 
makes this one unnecessary.

I guess the problematic thing is to refer to that core device header 
directly which makes things suspicious.

I'll change it.

Thanks!


>
>> +
>> +enum cxl_resource {
>> +	CXL_RES_DPA,
>> +	CXL_RES_RAM,
>> +	CXL_RES_PMEM,
>> +};
>> +
>> +struct cxl_dev_state *cxl_accel_state_create(struct device *dev);
>> +
>> +void cxl_set_dvsec(struct cxl_dev_state *cxlds, u16 dvsec);
>> +void cxl_set_serial(struct cxl_dev_state *cxlds, u64 serial);
>> +int cxl_set_resource(struct cxl_dev_state *cxlds, struct resource res,
>> +		     enum cxl_resource);
>> +#endif