On 21.08.2024 16:20, Alexander Lobakin wrote:
> From: Wojciech Drewek <wojciech.dre...@intel.com>
> Date: Wed, 21 Aug 2024 14:15:31 +0200
>
>> From: Jacob Keller <jacob.e.kel...@intel.com>
>>
>> Add the iavf_ptp.c file and fill it in with a skeleton framework to
>> allow registering the PTP clock device.
>> Add implementation of helper functions to check if a PTP capability
>> is supported and handle change in PTP capabilities.
>> Enabling virtual clock would be possible, though it would probably
>> perform poorly due to the lack of direct time access.
>
> [...]
>
>> +/**
>> + * iavf_ptp_register_clock - Register a new PTP for userspace
>> + * @adapter: private adapter structure
>> + *
>> + * Allocate and register a new PTP clock device if necessary.
>> + *
>> + * Return: 0 if success, error otherwise
>
> Period ('.') at the end is desired at the end of kdoc.
Sure
>
>> + */
>> +static int iavf_ptp_register_clock(struct iavf_adapter *adapter)
>> +{
>> + struct ptp_clock_info *ptp_info = &adapter->ptp.info;
>> + struct device *dev = &adapter->pdev->dev;
>> +
>> + memset(ptp_info, 0, sizeof(*ptp_info));
>
> Is this needed? adapter is allocated using kzalloc() I think?
I think it's not needed, adapter is allocated using alloc_etherdev_mq
since this is netdev's priv in iavf
>
>> +
>> + snprintf(ptp_info->name, sizeof(ptp_info->name), "%s-%s-clk",
>> + dev_driver_string(dev), dev_name(dev));
>
> dev_driver_string() can be just KBUILD_MODNAME when it's called inside
> the actual module. It's mostly used when you need to get a module name
> from a different module or core kernel code.
Makes sense
>
>> + ptp_info->owner = THIS_MODULE;
>> +
>> + adapter->ptp.clock = ptp_clock_register(ptp_info, dev);
>> + if (IS_ERR(adapter->ptp.clock)) {
>> + adapter->ptp.clock = NULL;
>> +
>> + return PTR_ERR(adapter->ptp.clock);
>
> Braino here.
> You first set ptp.clock to %NULL and then return PTR_ERR(ptp.clock).
> IOW, this error path will always return 0.
>
> I usually use temporary variables to avoid this.
>
> clock = ptp_clock_register(ptp_info, dev);
> if (IS_ERR(clock))
> return PTR_ERR(clock);
>
> adapter->ptp.clock = clock;
will fix
>
>
>> + }
>> +
>> + dev_dbg(&adapter->pdev->dev, "PTP clock %s registered\n",
>> + adapter->ptp.info.name);
>> +
>> + return 0;
>> +}
>> +
>> +/**
>> + * iavf_ptp_init - Initialize PTP support if capability was negotiated
>> + * @adapter: private adapter structure
>> + *
>> + * Initialize PTP functionality, based on the capabilities that the PF has
>> + * enabled for this VF.
>> + */
>> +void iavf_ptp_init(struct iavf_adapter *adapter)
>> +{
>> + int err;
>> +
>> + if (!iavf_ptp_cap_supported(adapter, VIRTCHNL_1588_PTP_CAP_READ_PHC)) {
>> + pci_warn(adapter->pdev,
>> + "Device does not have PTP clock support\n");
>
> I think it's pci_notice() or even pci_dbg(). A device can miss PTP
> clock, but it's not a failure. _warn() is when something went wrong, but
> not as wrong as _err() :D
sure
>
>> + return;
>> + }
>> +
>> + err = iavf_ptp_register_clock(adapter);
>> + if (err) {
>> + pci_err(adapter->pdev,
>> + "Failed to register PTP clock device (%p)\n",
>> + ERR_PTR(err));
>> + return;
>> + }
>
> Why does this function return void if there's an error path? To make
> sure the driver works even if PTP fails to register? But I think it's
> better to bail out if something failed than to work without certain
> functionality?
Most of the drivers don't bail out if ptp init failed, I'll stick to that.
>
>> +
>> + adapter->ptp.initialized = true;
>> +}
>> +
>> +/**
>> + * iavf_ptp_release - Disable PTP support
>> + * @adapter: private adapter structure
>> + *
>> + * Release all PTP resources that were previously initialized.
>> + */
>> +void iavf_ptp_release(struct iavf_adapter *adapter)
>> +{
>> + adapter->ptp.initialized = false;
>> +
>> + if (!IS_ERR_OR_NULL(adapter->ptp.clock)) {
>
> Since you always assign clock to %NULL when the initialization failed,
> this could be just
Yep
>
> if (adapter->ptp.clock)
>
>> + dev_dbg(&adapter->pdev->dev, "removing PTP clock %s\n",
>> + adapter->ptp.info.name);
>
> pci_dbg()
>
>> + ptp_clock_unregister(adapter->ptp.clock);
>> + adapter->ptp.clock = NULL;
>> + }
>
> ...but I'd invert the condition to avoid +1 indent level.
>
> if (!adapter->ptp.clock)
> return;
>
> pci_dbg() ...
Agree
>
>> +}
>> +
>> +/**
>> + * iavf_ptp_process_caps - Handle change in PTP capabilities
>> + * @adapter: private adapter structure
>> + *
>> + * Handle any state changes necessary due to change in PTP capabilities,
>> such
>> + * as after a device reset or change in configuration from the PF.
>> + */
>> +void iavf_ptp_process_caps(struct iavf_adapter *adapter)
>> +{
>> + bool read_phc = iavf_ptp_cap_supported(adapter,
>> + VIRTCHNL_1588_PTP_CAP_READ_PHC);
>
> Maybe split the declaration and initialization to avoid line break? My
> editor says it would fit in 80 if you make the variable name shorter,
> e.g. 'phc'.
Sure, why not
>
>> +
>> + /* Check if the device gained or lost necessary access to support the
>> + * PTP hardware clock. If so, driver must respond appropriately by
>> + * creating or destroying the PTP clock device.
>> + */
>> + if (adapter->ptp.initialized && !read_phc)
>> + iavf_ptp_release(adapter);
>> + else if (!adapter->ptp.initialized && read_phc)
>> + iavf_ptp_init(adapter);
>> +}
>
> Thanks,
> Olek
