linux-kernel - Re: [PATCH v2 06/17] PCI: designware-ep: Add generic function for raising MSI irq

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Message-ID: <3504bd0d-7e96-a9ac-2d9e-e0e81797eb19@axis.com>
Date:   Tue, 31 Oct 2017 22:06:24 +0100
From:   Niklas Cassel <niklas.cassel@...s.com>
To:     Kishon Vijay Abraham I <kishon@...com>,
        Jingoo Han <jingoohan1@...il.com>,
        Joao Pinto <Joao.Pinto@...opsys.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
CC:     <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 06/17] PCI: designware-ep: Add generic function for
 raising MSI irq

On 10/31/2017 07:22 AM, Kishon Vijay Abraham I wrote:

(snip)

>> --- a/drivers/pci/dwc/pcie-designware.h
>> +++ b/drivers/pci/dwc/pcie-designware.h
>> @@ -106,6 +106,8 @@
>>  #define MSI_CAP_MME_MASK		(7 << MSI_CAP_MME_SHIFT)
>>  #define MSI_MESSAGE_ADDR_L32		0x54
>>  #define MSI_MESSAGE_ADDR_U32		0x58
>> +#define MSI_MESSAGE_DATA_32		0x58
> 
> Does ADDR_U32 and DATA_32 share the same offset? (in dra7xx MSI_64_EN is
> hardwired to 1 so I can't know this for sure.)
> 

Hello Kishon,

Yes, they do.
The information in the register depends on if the bit MSI_64_EN
is set or not.

There exists defines for this also in the generic uapi header pci_regs.h,
however, utilizing that header would be a separate patch.

$ grep -E "MSI_DATA|MSI_MASK" include/uapi/linux/pci_regs.h
#define PCI_MSI_DATA_32         8       /* 16 bits of data for 32-bit devices */
#define PCI_MSI_MASK_32         12      /* Mask bits register for 32-bit devices */
#define PCI_MSI_DATA_64         12      /* 16 bits of data for 64-bit devices */
#define PCI_MSI_MASK_64         16      /* Mask bits register for 64-bit devices */

Regards,
Niklas