Re: [PATCH v3 1/5] MdeModulePkg: introduce non-discoverable device protocol

["Tian, Feng" <feng.tian@intel.com>]

Ard,

I have another question.

Is it the only way to specify device type in below enum? Looks like it will be changed often. Is it possible to make use of DevicePath node? Of course, I have no good idea to handle AMBA controller...

+//
+// Data Types
+//
+typedef enum {
+  NonDiscoverableDeviceTypeAmba,
+  NonDiscoverableDeviceTypeOhci,
+  NonDiscoverableDeviceTypeUhci,
+  NonDiscoverableDeviceTypeEhci,
+  NonDiscoverableDeviceTypeXhci,
+  NonDiscoverableDeviceTypeAhci,
+  NonDiscoverableDeviceTypeSdhci,
+  NonDiscoverableDeviceTypeUfs,
+  NonDiscoverableDeviceTypeNvme,
+  NonDiscoverableDeviceTypeMax,
+} NON_DISCOVERABLE_DEVICE_TYPE;

Thanks
Feng

-----Original Message-----
From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Ard Biesheuvel
Sent: Friday, November 18, 2016 12:59 PM
To: Ni, Ruiyu <ruiyu.ni@intel.com>
Cc: Kinney, Michael D <michael.d.kinney@intel.com>; edk2-devel@lists.01.org; Gao, Liming <liming.gao@intel.com>; afish@apple.com; Leif Lindholm <leif.lindholm@linaro.org>
Subject: Re: [edk2] [PATCH v3 1/5] MdeModulePkg: introduce non-discoverable device protocol

On 18 November 2016 at 02:11, Ni, Ruiyu <ruiyu.ni@intel.com> wrote:
>
>
> Regards,
> Ray
>
>>-----Original Message-----
>>From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
>>Sent: Thursday, November 17, 2016 6:43 PM
>>To: Ni, Ruiyu <ruiyu.ni@intel.com>
>>Cc: Kinney, Michael D <michael.d.kinney@intel.com>; 
>>edk2-devel@lists.01.org; Gao, Liming <liming.gao@intel.com>; 
>>afish@apple.com; Leif Lindholm <leif.lindholm@linaro.org>
>>Subject: Re: [edk2] [PATCH v3 1/5] MdeModulePkg: introduce 
>>non-discoverable device protocol
>>
>>
>>> On 17 Nov 2016, at 08:52, Ni, Ruiyu <ruiyu.ni@intel.com> wrote:
>>>
>>>
>>>
>>> Thanks/Ray
>>>
>>>> -----Original Message-----
>>>> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf 
>>>> Of Ard Biesheuvel
>>>> Sent: Thursday, November 17, 2016 2:07 PM
>>>> To: Ni, Ruiyu <ruiyu.ni@intel.com>
>>>> Cc: Kinney, Michael D <michael.d.kinney@intel.com>; edk2- 
>>>> devel@lists.01.org; Gao, Liming <liming.gao@intel.com>; 
>>>> afish@apple.com; Leif Lindholm <leif.lindholm@linaro.org>
>>>> Subject: Re: [edk2] [PATCH v3 1/5] MdeModulePkg: introduce non- 
>>>> discoverable device protocol
>>>>
>>>>
>>>>
>>>>> On 17 Nov 2016, at 02:53, Ni, Ruiyu <ruiyu.ni@intel.com> wrote:
>>>>>
>>>>> Ard,
>>>>> I have two comments in below.
>>>>>
>>>>> Thanks/Ray
>>>>>
>>>>>> -----Original Message-----
>>>>>> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On 
>>>>>> Behalf Of Leif Lindholm
>>>>>> Sent: Thursday, November 17, 2016 1:49 AM
>>>>>> To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>>>>> Cc: Ni, Ruiyu <ruiyu.ni@intel.com>; edk2-devel@lists.01.org; 
>>>>>> afish@apple.com; Gao, Liming <liming.gao@intel.com>; Kinney, 
>>>>>> Michael D <michael.d.kinney@intel.com>
>>>>>> Subject: Re: [edk2] [PATCH v3 1/5] MdeModulePkg: introduce non- 
>>>>>> discoverable device protocol
>>>>>>
>>>>>>> On Wed, Nov 16, 2016 at 04:59:27PM +0000, Ard Biesheuvel wrote:
>>>>>>> Introduce a protocol that can be exposed by a platform for 
>>>>>>> devices that are not discoverable, usually because they are 
>>>>>>> wired straight to the memory bus rather than to an enumerable bus like PCI or USB.
>>>>>>>
>>>>>>> Contributed-under: TianoCore Contribution Agreement 1.0
>>>>>>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>>>>>>> ---
>>>>>>> MdeModulePkg/Include/Protocol/NonDiscoverableDevice.h | 90
>>>>>> ++++++++++++++++++++
>>>>>>> MdeModulePkg/MdeModulePkg.dec                         |  3 +
>>>>>>> 2 files changed, 93 insertions(+)
>>>>>>>
>>>>>>> diff --git 
>>>>>>> a/MdeModulePkg/Include/Protocol/NonDiscoverableDevice.h
>>>>>>> b/MdeModulePkg/Include/Protocol/NonDiscoverableDevice.h
>>>>>>> new file mode 100644
>>>>>>> index 000000000000..47ed841b407b
>>>>>>> --- /dev/null
>>>>>>> +++ b/MdeModulePkg/Include/Protocol/NonDiscoverableDevice.h
>>>>>>> @@ -0,0 +1,90 @@
>>>>>>> +/** @file
>>>>>>> +  Protocol to describe devices that are not on a discoverable 
>>>>>>> +bus
>>>>>>> +
>>>>>>> +  Copyright (c) 2016, Linaro, Ltd. All rights reserved.<BR>
>>>>>>> +
>>>>>>> +  This program and the accompanying materials  are licensed and 
>>>>>>> + made available under the terms and conditions of the BSD 
>>>>>>> + License which accompanies this distribution.  The full text of 
>>>>>>> + the license may be found at  
>>>>>>> + http://opensource.org/licenses/bsd-license.php
>>>>>>> +
>>>>>>> +  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS
>>>> IS"
>>>>>>> + BASIS,  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND,
>>>>>> EITHER EXPRESS OR IMPLIED.
>>>>>>> +
>>>>>>> +**/
>>>>>>> +
>>>>>>> +#ifndef __NON_DISCOVERABLE_DEVICE_H__ #define 
>>>>>>> +__NON_DISCOVERABLE_DEVICE_H__
>>>>>>> +
>>>>>>> +#include <IndustryStandard/Acpi.h>
>>>>>>> +
>>>>>>> +#define EDKII_NON_DISCOVERABLE_DEVICE_PROTOCOL_GUID \
>>>>>>> +  { 0x0d51905b, 0xb77e, 0x452a, {0xa2, 0xc0, 0xec, 0xa0, 0xcc, 
>>>>>>> +0x8d, 0x51, 0x4a } }
>>>>>
>>>>> 1. Can you add "PCI" keyword into the protocol name?
>>>>> e.g.: EDKII_NON_DISCOVERABLE_PCI_DEVICE_PROTOCOL_GUID
>>>>>
>>>>
>>>> No. This protocol does not describe pci devices, and it is a 
>>>> peculiarity of the
>>>> edk2 driver stack that some non-pci devices can only be driven by pci drivers.
>>>>
>>>> in other words, pci is part of the /driver/ side, and it is 
>>>> perfectly possible for, e.g., a non-discoverable ahci device to be 
>>>> driven by a different non-pci driver in the future.
>>>>
>>>
>>> I see. So some types of devices are handled by the current 
>>> NonDiscoveablePciDevice driver, and some other types of devices may 
>>> be handled by a future NonDiscoverableXXXDevice driver.
>>> Now since the AHCI type is already handled by the 
>>> NonDiscoverablePciDevice driver, when there is a new 
>>> NonDiscoverableXXXDevice driver, how can the two know whether it should manage the AHCI type device or not?
>>
>>Good question. But how does the UEFI driver model deal with that? What 
>>happens if i have two drivers that both support the Ahci Pci class codes?
> PCI CFG header contains VendorID/DeviceID fields which can be used to 
> distinguish them.
>

No, that is not what I mean.

Your question is how we should deal with multiple drivers that support, for instance, the AHCI non-discoverable device type. My answer is that this is not any different from a platform configuration that has more than one PCI I/O based driver that supports the AHCI PCI class codes. The UEFI driver model has priority rules and protocols to decide which driver gets precedence. I don't see how it should be any different here.

Thanks,
Ard.
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