linux-kernel - Re: [PATCH v4 06/10] pci-epf-test/pci_endpoint_test: Cleanup PCI_ENDPOINT

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Date:   Wed, 20 Jun 2018 15:18:27 +0100
From:   Gustavo Pimentel <Gustavo.Pimentel@...opsys.com>
To:     Kishon Vijay Abraham I <kishon@...com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.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>,
        "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: [PATCH v4 06/10] pci-epf-test/pci_endpoint_test: Cleanup
 PCI_ENDPOINT_TEST memspace

Hi,

On 20/06/2018 08:53, Kishon Vijay Abraham I wrote:
> Hi,
> 
> On Monday 18 June 2018 08:30 PM, Gustavo Pimentel wrote:
>> Cleanup PCI_ENDPOINT_TEST memspace (by moving the interrupt number away
>> from command section).
>>
>> Signed-off-by: Gustavo Pimentel <gustavo.pimentel@...opsys.com>
>> ---
>> Change v2->v3:
>>  - New patch file created base on the previous patch
>> "misc: pci_endpoint_test: Add MSI-X support" patch file following
>> Kishon's suggestion.
>> Change v3->v4:
>>  - Rebased to Lorenzo's master branch v4.18-rc1.
>>
>>  drivers/misc/pci_endpoint_test.c              | 84 ++++++++++++++++-----------
>>  drivers/pci/endpoint/functions/pci-epf-test.c | 60 ++++++++++++-------
>>  2 files changed, 91 insertions(+), 53 deletions(-)
>>
>> diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
>> index 7b37046..56be808 100644
>> --- a/drivers/misc/pci_endpoint_test.c
>> +++ b/drivers/misc/pci_endpoint_test.c
>> @@ -35,38 +35,42 @@
>>  
>>  #include <uapi/linux/pcitest.h>
>>  
>> -#define DRV_MODULE_NAME			"pci-endpoint-test"
>> -
>> -#define PCI_ENDPOINT_TEST_MAGIC		0x0
>> -
>> -#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 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 DRV_MODULE_NAME				"pci-endpoint-test"
>> +
>> +#define IRQ_TYPE_LEGACY				0
>> +#define IRQ_TYPE_MSI				1
>> +
>> +#define PCI_ENDPOINT_TEST_MAGIC			0x0
>> +
>> +#define PCI_ENDPOINT_TEST_COMMAND		0x4
>> +#define COMMAND_RAISE_LEGACY_IRQ		BIT(0)
>> +#define COMMAND_RAISE_MSI_IRQ			BIT(1)
> 
> Maybe you can add a comment here that BIT(2) is reserved for MSIX support

Sure.

>> +#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	0x0c
>>  #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_SIZE			0x1c
>> +#define PCI_ENDPOINT_TEST_CHECKSUM		0x20
>> +
>> +#define PCI_ENDPOINT_TEST_IRQ_TYPE		0x24
> 
> Is this not redundant? COMMAND_RAISE_LEGACY_IRQ, COMMAND_RAISE_MSI_IRQ already
> indicates the irq type to be used.

In previous implementation the distinction between interrupt types was simpler,
basically legacy *number* always set as zero and the MSI *number* always
non-zero. However by introducing the MSI-X this simple mechanism is no longer
valid, because the MSI-X *number* is also always non-zero like as MSI.
Therefore is necessary to distinguish which interrupt type was been triggered
(MSI or MSI-X) especially for the Write/Read/Copy tests.


>> +#define PCI_ENDPOINT_TEST_IRQ_NUMBER		0x28
>>  
>>  static DEFINE_IDA(pci_endpoint_test_ida);
>>  
>> @@ -179,6 +183,9 @@ static bool pci_endpoint_test_legacy_irq(struct pci_endpoint_test *test)
>>  {
>>  	u32 val;
>>  
>> +	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_IRQ_TYPE,
>> +				 IRQ_TYPE_LEGACY);
>> +	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_IRQ_NUMBER, 0);
> 
> Not sure if the above writes are really required.

Is not required, but I added those write for keeping the code coherency between
pci_endpoint_test_legacy_irq() and pci_endpoint_test_msi_irq(), basically both
functions write on the same registers. I think it doesn't cause any harm.

>>  	pci_endpoint_test_writel(test, PCI_ENDPOINT_TEST_COMMAND,
>>  				 COMMAND_RAISE_LEGACY_IRQ);
>>  	val = wait_for_completion_timeout(&test->irq_raised,
>> @@ -190,20 +197,22 @@ static bool pci_endpoint_test_legacy_irq(struct pci_endpoint_test *test)
>>  }
>>  
>>  static bool pci_endpoint_test_msi_irq(struct pci_endpoint_test *test,
>> -				      u8 msi_num)
>> +				      u8 irq_num)
> 
> why do you want to rename this?

Initially this patch file contained the changes related to MSI-X support and by
that time I had changed the name of this variable so that its name had a broader
meaning that contemplated these two types. Now that I see this, I think the
original name may also be valid, I will revert this name change.

Regards,
Gustavo

> 
> Thanks
> Kishon
>