linux-kernel - Re: [PATCH 1/4] PCI: dwc: Add new feature to skip core initialization

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Message-ID: <2c9a860f-4700-87e9-2538-9b0d40c9ce34@nvidia.com>
Date:   Thu, 5 Dec 2019 15:29:25 +0530
From:   Vidya Sagar <vidyas@...dia.com>
To:     Christoph Hellwig <hch@...radead.org>
CC:     <jingoohan1@...il.com>, <gustavo.pimentel@...opsys.com>,
        <lorenzo.pieralisi@....com>, <andrew.murray@....com>,
        <bhelgaas@...gle.com>, <kishon@...com>, <thierry.reding@...il.com>,
        <Jisheng.Zhang@...aptics.com>, <jonathanh@...dia.com>,
        <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <kthota@...dia.com>, <mmaddireddy@...dia.com>, <sagar.tv@...il.com>
Subject: Re: [PATCH 1/4] PCI: dwc: Add new feature to skip core initialization

On 11/29/2019 8:10 PM, Vidya Sagar wrote:

Hi Christoph,
Could you please let me know what am I missing here?

Thanks,
Vidya Sagar

> On 11/27/2019 3:18 PM, Christoph Hellwig wrote:
>> On Wed, Nov 13, 2019 at 02:38:48PM +0530, Vidya Sagar wrote:
>>> +    if (ep->ops->get_features) {
>>> +        epc_features = ep->ops->get_features(ep);
>>> +        if (epc_features->skip_core_init)
>>> +            return 0;
>>>       }
>>> +    return dw_pcie_ep_init_complete(ep);
>>
>> This calling convention is strange.  Just split the early part of
>> dw_pcie_ep_init into an dw_pcie_ep_early and either add a tiny
>> wrapper like:
>>
>> int dw_pcie_ep_init(struct dw_pcie_ep *ep)
>> {
>>     int error;
>>
>>     error = dw_pcie_ep_init_early(ep);
>>     if (error)
>>         return error;
>>     return dw_pcie_ep_init_late(ep);
>> }
>>
>> or just open code that in the few callers.  That keeps the calling
>> conventions much simpler and avoids relying on a callback and flag.
> I'm not sure if I got this right. I think in any case, code that is going to be
> part of dw_pcie_ep_init_late() needs to depend on callback and flag right?
> I mean, unless it is confirmed (by calling the get_features() callback and
> checking whether or not the core is available for programming) dw_pcie_ep_init_late()
> can't be called right?
> Please let me know if I'm missing something here.
> 
> - Vidya Sagar
>>
>