linux-kernel - Re: [RFC 06/10] misc: pci_endpoint

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Date:   Tue, 24 Apr 2018 11:57:09 +0100
From:   Gustavo Pimentel <gustavo.pimentel@...opsys.com>
To:     Kishon Vijay Abraham I <kishon@...com>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "Joao.Pinto@...opsys.com" <Joao.Pinto@...opsys.com>,
        "jingoohan1@...il.com" <jingoohan1@...il.com>,
        "adouglas@...ence.com" <adouglas@...ence.com>,
        "niklas.cassel@...s.com" <niklas.cassel@...s.com>,
        "jesper.nilsson@...s.com" <jesper.nilsson@...s.com>
Cc:     "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC 06/10] misc: pci_endpoint_test: Add MSI-X support

Hi Kishon,

On 24/04/2018 08:19, Kishon Vijay Abraham I wrote:
> Hi,
> 
> On Tuesday 17 April 2018 11:08 PM, Gustavo Pimentel wrote:
>> Hi Kishon,
>>
>> On 17/04/2018 11:33, Kishon Vijay Abraham I wrote:
>>> Hi,
>>>
>>> On Tuesday 10 April 2018 10:44 PM, Gustavo Pimentel wrote:
>>>> Adds the MSI-X support and updates driver documentation accordingly.
>>>>
>>>> Changes the driver parameter in order to allow the interruption type
>>>> selection.
>>>>
>>>> Signed-off-by: Gustavo Pimentel <gustavo.pimentel@...opsys.com>
>>>> ---
>>>>  Documentation/misc-devices/pci-endpoint-test.txt |   3 +
>>>>  drivers/misc/pci_endpoint_test.c                 | 102 +++++++++++++++++------
>>>>  2 files changed, 79 insertions(+), 26 deletions(-)
>>>>
>>>> diff --git a/Documentation/misc-devices/pci-endpoint-test.txt b/Documentation/misc-devices/pci-endpoint-test.txt
>>>> index 4ebc359..fdfa0f6 100644
>>>> --- a/Documentation/misc-devices/pci-endpoint-test.txt
>>>> +++ b/Documentation/misc-devices/pci-endpoint-test.txt
>>>> @@ -10,6 +10,7 @@ The PCI driver for the test device performs the following tests
>>>>  	*) verifying addresses programmed in BAR
>>>>  	*) raise legacy IRQ
>>>>  	*) raise MSI IRQ
>>>> +	*) raise MSI-X IRQ
>>>>  	*) read data
>>>>  	*) write data
>>>>  	*) copy data
>>>> @@ -25,6 +26,8 @@ ioctl
>>>>   PCITEST_LEGACY_IRQ: Tests legacy IRQ
>>>>   PCITEST_MSI: Tests message signalled interrupts. The MSI number
>>>>  	      to be tested should be passed as argument.
>>>> + PCITEST_MSIX: Tests message signalled interrupts. The MSI-X number
>>>> +	      to be tested should be passed as argument.
>>>>   PCITEST_WRITE: Perform write tests. The size of the buffer should be passed
>>>>  		as argument.
>>>>   PCITEST_READ: Perform read tests. The size of the buffer should be passed
>>>> diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
>>>> index 37db0fc..a7d9354 100644
>>>> --- a/drivers/misc/pci_endpoint_test.c
>>>> +++ b/drivers/misc/pci_endpoint_test.c
>>>> @@ -42,11 +42,16 @@
>>>>  #define PCI_ENDPOINT_TEST_COMMAND	0x4
>>>>  #define COMMAND_RAISE_LEGACY_IRQ	BIT(0)
>>>>  #define COMMAND_RAISE_MSI_IRQ		BIT(1)
>>>> -#define MSI_NUMBER_SHIFT		2
>>>> -/* 6 bits for MSI number */
>>>> -#define COMMAND_READ                    BIT(8)
>>>> -#define COMMAND_WRITE                   BIT(9)
>>>> -#define COMMAND_COPY                    BIT(10)
>>>> +#define COMMAND_RAISE_MSIX_IRQ		BIT(2)
>>>> +#define IRQ_TYPE_SHIFT			3
>>>> +#define IRQ_TYPE_LEGACY			0
>>>> +#define IRQ_TYPE_MSI			1
>>>> +#define IRQ_TYPE_MSIX			2
>>>> +#define MSI_NUMBER_SHIFT		5
>>>
>>> Now that you are anyways fixing this, add a new register entry for MSI numbers.
>>> Let's not keep COMMAND and MSI's together.
>>
>> What you suggest?
> 
> #define PCI_ENDPOINT_TEST_COMMAND	0x4
> #define COMMAND_RAISE_LEGACY_IRQ	BIT(0)
> #define COMMAND_RAISE_MSI_IRQ		BIT(1)
> #define COMMAND_RAISE_MSIX_IRQ		BIT(2)
> #define COMMAND_READ                    BIT(3)
> #define COMMAND_WRITE                   BIT(4)
> #define COMMAND_COPY                    BIT(5)
> 
> #define PCI_ENDPOINT_TEST_STATUS	0x8
> #define STATUS_READ_SUCCESS             BIT(0)
> #define STATUS_READ_FAIL                BIT(1)
> #define STATUS_WRITE_SUCCESS            BIT(2)
> #define STATUS_WRITE_FAIL               BIT(3)
> #define STATUS_COPY_SUCCESS             BIT(4)
> #define STATUS_COPY_FAIL                BIT(5)
> #define STATUS_IRQ_RAISED               BIT(6)
> #define STATUS_SRC_ADDR_INVALID         BIT(7)
> #define STATUS_DST_ADDR_INVALID         BIT(8)
> 
> #define PCI_ENDPOINT_TEST_LOWER_SRC_ADDR	0xc
> #define PCI_ENDPOINT_TEST_UPPER_SRC_ADDR	0x10
> 
> #define PCI_ENDPOINT_TEST_LOWER_DST_ADDR	0x14
> #define PCI_ENDPOINT_TEST_UPPER_DST_ADDR	0x18
> 
> #define PCI_ENDPOINT_TEST_SIZE		0x1c
> #define PCI_ENDPOINT_TEST_CHECKSUM	0x20
> 
> #define PCI_ENDPOINT_TEST_MSI_NUMBER	0x24

Ok. I will do it.

> 
> We should try not to modify either the existing register offsets or the bit
> fields within these registers in the future as EP and RC will be running on
> different systems and it is possible one of them might not have the updated
> kernel.

I totally agree.

>>
>>>> +/* 12 bits for MSI number */
>>>> +#define COMMAND_READ                    BIT(17)
>>>> +#define COMMAND_WRITE                   BIT(18)
>>>> +#define COMMAND_COPY                    BIT(19)
>>>
>>> This change should be done along with the pci-epf-test in a single patch.
>>
>> To be clear, you're saying is this patch should be just be squashed into the
>> patch number 8 [1], because there is a lot of dependencies namely the defines,
>> that is used on the alter functions.
>>
>> [1] -> https://urldefense.proofpoint.com/v2/url?u=https-3A__patchwork.ozlabs.org_patch_896841_&d=DwIC-g&c=DPL6_X_6JkXFx7AXWqB0tg&r=bkWxpLoW-f-E3EdiDCCa0_h0PicsViasSlvIpzZvPxs&m=8urVwHCybXa1XMxsEbwHZAzzaEI_HJGXqmWgXpXb9TY&s=MRVr2YPY2Bk_WNFOxBfU4FGrFReTKdPhfzNDLiVxDbs&e=
> 
> yeah. We have to make sure git bisect doesn't break functionality.

Ok, it'll be squashed.

>>
>>>>  
>>>>  #define PCI_ENDPOINT_TEST_STATUS	0x8
>>>>  #define STATUS_READ_SUCCESS             BIT(0)
>>>> @@ -73,9 +78,9 @@ static DEFINE_IDA(pci_endpoint_test_ida);
>>>>  #define to_endpoint_test(priv) container_of((priv), struct pci_endpoint_test, \
>>>>  					    miscdev)
>>>>  
>>>> -static bool no_msi;
>>>> -module_param(no_msi, bool, 0444);
>>>> -MODULE_PARM_DESC(no_msi, "Disable MSI interrupt in pci_endpoint_test");
>>>
>>> Let's not remove this just to make sure existing users doesn't get affected.
>>
>> Hum, by making an internal conversion? Like this
>> no_msi = false <=> irq_type = 1
>> no_msi = true <=> irq_type = 0
> 
Disregard previous comment, it doesn't make sense. I don't know where my head was.

It will be like this on probe:

if (no_msi)
	irq_type = IRQ_TYPE_LEGACY;

However since we are breaking the compatibility on terms of MSI/MSI-X
bits/registers (discussion on the top), it makes sense to keep the compatibility
on this parameter?

> yeah..
> 
> Thanks
> Kishon
> 

Regards,
Gustavo