linux-kernel - Re: [RFC PATCH v2 01/32] PCI: add pcie_flags_reg into struct pci

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Date:	Thu, 26 Jul 2012 21:47:10 +0800
From:	Yijing Wang <wangyijing0307@...il.com>
To:	Don Dutile <ddutile@...hat.com>
CC:	Jiang Liu <liuj97@...il.com>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Yijing Wang <wangyijing@...wei.com>,
	Yinghai Lu <yinghai@...nel.org>,
	Taku Izumi <izumi.taku@...fujitsu.com>,
	"Rafael J . Wysocki" <rjw@...k.pl>,
	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [RFC PATCH v2 01/32] PCI: add pcie_flags_reg into struct pci_dev
 to cache PCIe capabilities register

于 2012-07-25 23:12, Don Dutile 写道:
> resending since i did a reply vs reply-all last time...
> 
> On 07/24/2012 12:31 PM, Jiang Liu wrote:
>> From: Yijing Wang<wangyijing@...wei.com>
>>
>> From: Yijing Wang<wangyijing@...wei.com>
>>
>> Since PCI Express Capabilities Register is read only, cache its value
>> into struct pci_dev to avoid repeatedly calling pci_read_config_*().
>>
>> Signed-off-by: Yijing Wang<wangyijing@...wei.com>
>> Signed-off-by: Jiang Liu<liuj97@...il.com>
>> ---
>>   drivers/pci/probe.c |    1 +
>>   include/linux/pci.h |   10 ++++++++++
>>   2 files changed, 11 insertions(+)
>>
>> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
>> index 6c143b4..6fd58df 100644
>> --- a/drivers/pci/probe.c
>> +++ b/drivers/pci/probe.c
>> @@ -929,6 +929,7 @@ void set_pcie_port_type(struct pci_dev *pdev)
>>       pdev->is_pcie = 1;
>>       pdev->pcie_cap = pos;
>>       pci_read_config_word(pdev, pos + PCI_EXP_FLAGS,&reg16);
>> +    pdev->pcie_flags_reg = reg16;
>>       pdev->pcie_type = (reg16&  PCI_EXP_FLAGS_TYPE)>>  4;
> So, given the patch below, shouldn't the above line be ?
>     pdev->pcie_type = pci_pcie_type(pdev);
> 
Hi,Don Dutile,thanks for your comments very much!
> Missed part of patch ?
pdev->pcie_type was removed in the later patch([RFC PATCH v2 03/32] PCI: remove unused field pcie_type from struct pci_dev),
so I leave it here unmodified.
But your suggestion let this patch become more reasonable.
Thanks.
> 
>>       pci_read_config_word(pdev, pos + PCI_EXP_DEVCAP,&reg16);
>>       pdev->pcie_mpss = reg16&  PCI_EXP_DEVCAP_PAYLOAD;
>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>> index 5faa831..95662b2 100644
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -258,6 +258,7 @@ struct pci_dev {
>>       u8        pcie_mpss:3;    /* PCI-E Max Payload Size Supported */
>>       u8        rom_base_reg;    /* which config register controls the ROM */
>>       u8        pin;          /* which interrupt pin this device uses */
>> +    u16        pcie_flags_reg;    /* cached PCI-E Capabilities Register */
>>
>>       struct pci_driver *driver;    /* which driver has allocated this device */
>>       u64        dma_mask;    /* Mask of the bits of bus address this
>> @@ -1650,6 +1651,15 @@ static inline bool pci_is_pcie(struct pci_dev *dev)
>>       return !!pci_pcie_cap(dev);
>>   }
>>
>> +/**
>> + * pci_pcie_type - get the PCIe device/port type
>> + * @dev: PCI device
>> + */
>> +static inline int pci_pcie_type(const struct pci_dev *dev)
>> +{
>> +    return (dev->pcie_flags_reg&  PCI_EXP_FLAGS_TYPE)>>  4;
>> +}
>> +
>>   void pci_request_acs(void);
>>   bool pci_acs_enabled(struct pci_dev *pdev, u16 acs_flags);
>>   bool pci_acs_path_enabled(struct pci_dev *start,
> 
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