On 2020/4/24 14:02, Saheed Bolarinwa wrote:
>
> On 4/24/20 12:38 AM, Bjorn Helgaas wrote:
>> On Thu, Apr 23, 2020 at 07:55:17PM +0800, Yicong Yang wrote:
>>> On 2020/4/19 14:51, Bolarinwa Olayemi Saheed wrote:
>>>> diff --git a/drivers/pci/access.c b/drivers/pci/access.c
>>>> index 79c4a2ef269a..451f2b8b2b3c 100644
>>>> --- a/drivers/pci/access.c
>>>> +++ b/drivers/pci/access.c
>>>> @@ -409,7 +409,7 @@ int pcie_capability_read_word(struct pci_dev *dev, int pos, u16 *val)
>>> Maybe provide some comments for the function, to notify the outside
>>> users to do the error code conversion.
>> A short function comment about the set of possible return values
>> wouldn't hurt. We don't have those for pci_read_config_word() and
>> friends, and there are several pcie_capability_*() functions. I don't
>> think it's worth repeating the comment for every function, so maybe we
>> could just extend the existing comment at pcie_capability_read_word().
>
> Is enough to adjust the comment on pcie_capability_read_word() to this:
>
> /*
> * Note that these accessor functions are only for the "PCI Express
> * Capability" (see PCIe spec r3.0, sec 7.8). They do not apply to the
> * other "PCI Express Extended Capabilities" (AER, VC, ACS, MFVC, etc.)
> *
> * On error, this function returns a PCIBIOS_* error code,
> * you may want to use pcibios_err_to_errno()(include/linux/pci.h)
> * to convert to a non-PCI code
> */
okay. Or we can provide kernel-doc as you wish.
>
>>> BTW, pci_{read, write}_config_*() may also have the issues that
>>> export the private err code outside. You may want to solve these in
>>> a series along with this patch.
>> If you see a specific issue, please point it out.
arch/x86/platform/intel/iosf_mbi.c, iosf_mbi_pci_read_mdr():
result = pci_read_config_dword(mbi_pdev, MBI_MDR_OFFSET, mdr);
if (result < 0)
goto fail_read;
return 0;
fail_read:
dev_err(&mbi_pdev->dev, "PCI config access failed with %d\n", result);
return result;
Not sure if there is much in the kernel.
>>
>> I looked at pci_read_config_word(), and it can return
>> PCIBIOS_DEVICE_NOT_FOUND, PCIBIOS_BAD_REGISTER_NUMBER, or the return
>> value from bus->ops->read().
>>
>> I looked at all the users of PCIBIOS_*. There's really no interesting
>> use of any of them except by pcibios_err_to_errno() and
>> xen_pcibios_err_to_errno(), so I'm not sure it's even worth keeping
>> them.
maybe we can mark them as deprecated. I can send a RFC one to do so.
>>
>> But I think it's probably more work to excise all of them than it is
>> to simply make pci_read_config_word() and pcie_capability_read_word()
>> return the same set of error values. So I think we should do this
>> first.
>>
okay.
>>>> *val = 0;
>>>> if (pos & 1)
>>>> - return -EINVAL;
>>>> + return PCIBIOS_BAD_REGISTER_NUMBER;
>>>> if (pcie_capability_reg_implemented(dev, pos)) {
>>>> ret = pci_read_config_word(dev, pci_pcie_cap(dev) + pos, val);
>>>> @@ -444,7 +444,7 @@ int pcie_capability_read_dword(struct pci_dev *dev, int pos, u32 *val)
>>>> *val = 0;
>>>> if (pos & 3)
>>>> - return -EINVAL;
>>>> + return PCIBIOS_BAD_REGISTER_NUMBER;
>>>> if (pcie_capability_reg_implemented(dev, pos)) {
>>>> ret = pci_read_config_dword(dev, pci_pcie_cap(dev) + pos, val);
>
> Also, can I just send this as a single patch while we conclude on pcie_capability_write*() ?
Sure. As Bjorn suggested.
Regards.
Yicong
>
> Thank you.
>
> - Saheed
>
> .
>
