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

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Message-ID: <20230803174858.GA103086@bhelgaas>
Date:   Thu, 3 Aug 2023 12:48:58 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Krishna chaitanya chundru <quic_krichai@...cinc.com>
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 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)

> +
> +   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.

> +	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
>