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    SubjectRe: [PATCH v2 02/11] PCI: Add the pci_get_class_masked() helper
    From
    Hi,


    On 2023/8/9 22:01, Ilpo Järvinen wrote:
    > On Wed, 9 Aug 2023, Sui Jingfeng wrote:
    >
    >> From: Sui Jingfeng <suijingfeng@loongson.cn>
    >>
    >> Because there is no good way to get the mask member used to searching for
    >> devices that conform to a specific PCI class code, an application needs to
    >> process all PCI display devices can achieve its goal as follows:
    > This is mixing old and new way in a single sentence (which is confusing)?


    Thanks for reviewing, but I can't understand this sentence.
    Are you telling me that my description have grammar problem or something else?


    I means that before apply this patch, we don't have a function can be used
    to get all PCI(e) devices in a system by matching against its the PCI base class code only,
    while keep the Sub-Class code and the Programming Interface ignored.
    By supply a mask as argument, such thing become possible.

    If an application want to process all PCI display devices in the system,
    then it can achieve its goal by calling pci_get_class_masked() function.


    >> pdev = NULL;
    >> do {
    >> pdev = pci_get_class_masked(PCI_BASE_CLASS_DISPLAY << 16, 0xFF0000, pdev);
    >> if (pdev)
    >> do_something_for_pci_display_device(pdev);
    >> } while (pdev);
    >>
    >> While previously, we just can not ignore Sub-Class code and the Programming
    > cannot
    >
    >> Interface byte when do the searching.
    > doing the search.


    OK, will be fixed at the next version.


    >> Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn>
    >> ---
    >> drivers/pci/search.c | 30 ++++++++++++++++++++++++++++++
    >> include/linux/pci.h | 7 +++++++
    >> 2 files changed, 37 insertions(+)
    >>
    >> diff --git a/drivers/pci/search.c b/drivers/pci/search.c
    >> index b4c138a6ec02..f1c15aea868b 100644
    >> --- a/drivers/pci/search.c
    >> +++ b/drivers/pci/search.c
    >> @@ -334,6 +334,36 @@ struct pci_dev *pci_get_device(unsigned int vendor, unsigned int device,
    >> }
    >> EXPORT_SYMBOL(pci_get_device);
    >>
    >> +/**
    >> + * pci_get_class_masked - begin or continue searching for a PCI device by class and mask
    >> + * @class: search for a PCI device with this class designation
    >> + * @from: Previous PCI device found in search, or %NULL for new search.
    >> + *
    >> + * Iterates through the list of known PCI devices. If a PCI device is
    > No double spaces in kernel comments. Perhaps your editor might be adding
    > them on reflow (might be configurable to not do that).
    >
    >> + * found with a matching @class, the reference count to the device is
    >> + * incremented and a pointer to its device structure is returned.
    >> + * Otherwise, %NULL is returned.
    >> + * A new search is initiated by passing %NULL as the @from argument.
    >> + * Otherwise if @from is not %NULL, searches continue from next device
    >> + * on the global list. The reference count for @from is always decremented
    >> + * if it is not %NULL.
    > Use kerneldoc's Return: section for describing return value.
    >
    >> + */
    >> +struct pci_dev *pci_get_class_masked(unsigned int class, unsigned int mask,
    >> + struct pci_dev *from)
    >> +{
    >> + struct pci_device_id id = {
    >> + .vendor = PCI_ANY_ID,
    >> + .device = PCI_ANY_ID,
    >> + .subvendor = PCI_ANY_ID,
    >> + .subdevice = PCI_ANY_ID,
    >> + .class_mask = mask,
    >> + .class = class,
    >> + };
    >> +
    >> + return pci_get_dev_by_id(&id, from);
    >> +}
    >> +EXPORT_SYMBOL(pci_get_class_masked);
    >> +
    >> /**
    >> * pci_get_class - begin or continue searching for a PCI device by class
    >> * @class: search for a PCI device with this class designation
    >> diff --git a/include/linux/pci.h b/include/linux/pci.h
    >> index 0ff7500772e6..b20e7ba844bf 100644
    >> --- a/include/linux/pci.h
    >> +++ b/include/linux/pci.h
    >> @@ -1180,6 +1180,9 @@ struct pci_dev *pci_get_slot(struct pci_bus *bus, unsigned int devfn);
    >> struct pci_dev *pci_get_domain_bus_and_slot(int domain, unsigned int bus,
    >> unsigned int devfn);
    >> struct pci_dev *pci_get_class(unsigned int class, struct pci_dev *from);
    >> +struct pci_dev *pci_get_class_masked(unsigned int class, unsigned int mask,
    >> + struct pci_dev *from);
    >> +
    >> int pci_dev_present(const struct pci_device_id *ids);
    >>
    >> int pci_bus_read_config_byte(struct pci_bus *bus, unsigned int devfn,
    >> @@ -1895,6 +1898,10 @@ static inline struct pci_dev *pci_get_class(unsigned int class,
    >> struct pci_dev *from)
    >> { return NULL; }
    >>
    >> +static inline struct pci_dev *pci_get_class_masked(unsigned int class,
    >> + unsigned int mask,
    >> + struct pci_dev *from)
    >> +{ return NULL; }
    >>
    >> static inline int pci_dev_present(const struct pci_device_id *ids)
    >> { return 0; }
    >>

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