linux-kernel - Re: [PATCH v5 1/4] PCI: endpoint: Add D-state change notifier support

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Message-ID: <ae239a22-a038-c4d4-c715-cb775de82659@quicinc.com>
Date:   Fri, 8 Sep 2023 10:11:19 +0530
From:   Krishna Chaitanya Chundru <quic_krichai@...cinc.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
CC:     <manivannan.sadhasivam@...aro.org>, <linux-pci@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <quic_vbadigan@...cinc.com>, <quic_nitegupt@...cinc.com>,
        <quic_skananth@...cinc.com>, <quic_ramkri@...cinc.com>,
        <quic_parass@...cinc.com>, <krzysztof.kozlowski@...aro.org>,
        "Lorenzo Pieralisi" <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Manivannan Sadhasivam <mani@...nel.org>,
        "Kishon Vijay Abraham I" <kishon@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>
Subject: Re: [PATCH v5 1/4] PCI: endpoint: Add D-state change notifier support


On 8/3/2023 11:18 PM, Bjorn Helgaas wrote:
> On Wed, Aug 02, 2023 at 09:21:18AM +0530, Krishna chaitanya chundru wrote:
>> Add support to notify the EPF device about the D-state change event
>> from the EPC device.
>>
>> Signed-off-by: Krishna chaitanya chundru <quic_krichai@...cinc.com>
>> ---
>>   Documentation/PCI/endpoint/pci-endpoint.rst |  4 ++++
>>   drivers/pci/endpoint/pci-epc-core.c         | 27 +++++++++++++++++++++++++++
>>   include/linux/pci-epc.h                     |  1 +
>>   include/linux/pci-epf.h                     |  1 +
>>   4 files changed, 33 insertions(+)
>>
>> diff --git a/Documentation/PCI/endpoint/pci-endpoint.rst b/Documentation/PCI/endpoint/pci-endpoint.rst
>> index 4f5622a..66f3191 100644
>> --- a/Documentation/PCI/endpoint/pci-endpoint.rst
>> +++ b/Documentation/PCI/endpoint/pci-endpoint.rst
>> @@ -78,6 +78,10 @@ by the PCI controller driver.
>>      Cleanup the pci_epc_mem structure allocated during pci_epc_mem_init().
>>   
>>   
>> +* pci_epc_dstate_notity()
> s/notity/notify/ (several instances)

sorry for late reply, till now I was using a different branch which has 
some out of tree patches for testing and rebasing the patch on 
linux-next to send them because of that few things are getting missed.

Now I took time to completely move to the linux next so that testing and 
sending patches will be on same code base.

>> +
>> +   Notify all the function drivers that the EPC device has changed its D-state.
>> +
>>   EPC APIs for the PCI Endpoint Function Driver
>>   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>   
>> diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
>> index 6c54fa5..4cf9c82 100644
>> --- a/drivers/pci/endpoint/pci-epc-core.c
>> +++ b/drivers/pci/endpoint/pci-epc-core.c
>> @@ -785,6 +785,33 @@ void pci_epc_bme_notify(struct pci_epc *epc)
>>   EXPORT_SYMBOL_GPL(pci_epc_bme_notify);
>>   
>>   /**
>> + * pci_epc_dstate_notity() - Notify the EPF driver that EPC device D-state
>> + *			has changed
>> + * @epc: the EPC device which has change in D-state
>> + * @state: the changed D-state
>> + *
>> + * Invoke to Notify the EPF device that the EPC device has D-state has
>> + * changed.
> s/device has D-state/device D-state/
>
>> + */
>> +void pci_epc_dstate_notity(struct pci_epc *epc, pci_power_t state)
>> +{
>> +	struct pci_epf *epf;
>> +
>> +	if (!epc || IS_ERR(epc))
>> +		return;
> Is this needed?  Looks like a programming error if we return here.  I
> don't like silently ignoring errors like this.  I generally prefer
> taking the NULL pointer dereference oops so we know the caller is
> broken and can fix it.
sure I will remove this check in the next patch series.
>
>> +	mutex_lock(&epc->list_lock);
>> +	list_for_each_entry(epf, &epc->pci_epf, list) {
>> +		mutex_lock(&epf->lock);
>> +		if (epf->event_ops && epf->event_ops->dstate_notify)
>> +			epf->event_ops->dstate_notify(epf, state);
>> +		mutex_unlock(&epf->lock);
>> +	}
>> +	mutex_unlock(&epc->list_lock);
>> +}
>> +EXPORT_SYMBOL_GPL(pci_epc_dstate_notity);
>> +
>> +/**
>>    * pci_epc_destroy() - destroy the EPC device
>>    * @epc: the EPC device that has to be destroyed
>>    *
>> diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
>> index 5cb6940..26a1108 100644
>> --- a/include/linux/pci-epc.h
>> +++ b/include/linux/pci-epc.h
>> @@ -251,4 +251,5 @@ void __iomem *pci_epc_mem_alloc_addr(struct pci_epc *epc,
>>   				     phys_addr_t *phys_addr, size_t size);
>>   void pci_epc_mem_free_addr(struct pci_epc *epc, phys_addr_t phys_addr,
>>   			   void __iomem *virt_addr, size_t size);
>> +void pci_epc_dstate_change(struct pci_epc *epc, pci_power_t state);
>>   #endif /* __LINUX_PCI_EPC_H */
>> diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h
>> index 3f44b6a..529075b 100644
>> --- a/include/linux/pci-epf.h
>> +++ b/include/linux/pci-epf.h
>> @@ -79,6 +79,7 @@ struct pci_epc_event_ops {
>>   	int (*link_up)(struct pci_epf *epf);
>>   	int (*link_down)(struct pci_epf *epf);
>>   	int (*bme)(struct pci_epf *epf);
>> +	int (*dstate_notify)(struct pci_epf *epf, pci_power_t state);
>>   };
>>   
>>   /**
>> -- 
>> 2.7.4
>>