linux-kernel - Re: [PATCH v5] usb: xhci-mtk: fix unreleased bandwidth data

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Message-ID: <e43632e2-08b3-7a1a-8272-1d493e25fc67@linux.intel.com>
Date:   Fri, 8 Jan 2021 16:46:38 +0200
From:   Mathias Nyman <mathias.nyman@...ux.intel.com>
To:     Chunfeng Yun <chunfeng.yun@...iatek.com>
Cc:     Ikjoon Jang <ikjn@...omium.org>,
        linux-mediatek@...ts.infradead.org, linux-usb@...r.kernel.org,
        Tianping Fang <tianping.fang@...iatek.com>,
        Zhanyong Wang <zhanyong.wang@...iatek.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5] usb: xhci-mtk: fix unreleased bandwidth data

On 8.1.2021 8.11, Chunfeng Yun wrote:
> On Thu, 2021-01-07 at 13:09 +0200, Mathias Nyman wrote:
>> On 29.12.2020 8.24, Ikjoon Jang wrote:
>>> xhci-mtk has hooks on add_endpoint() and drop_endpoint() from xhci
>>> to handle its own sw bandwidth managements and stores bandwidth data
>>> into internal table every time add_endpoint() is called,
>>> so when bandwidth allocation fails at one endpoint, all earlier
>>> allocation from the same interface could still remain at the table.
>>>
>>> This patch adds two more hooks from check_bandwidth() and
>>> reset_bandwidth(), and make mtk-xhci to releases all failed endpoints
>>> from reset_bandwidth().
>>>
>>> Fixes: 08e469de87a2 ("usb: xhci-mtk: supports bandwidth scheduling with multi-TT")
>>> Signed-off-by: Ikjoon Jang <ikjn@...omium.org>
>>>
>>
>> ...
>>
>>>
>>> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
>>> index d4a8d0efbbc4..e1fcd3cf723f 100644
>>> --- a/drivers/usb/host/xhci.c
>>> +++ b/drivers/usb/host/xhci.c
>>> @@ -2882,6 +2882,12 @@ static int xhci_check_bandwidth(struct usb_hcd *hcd, struct usb_device *udev)
>>>  	xhci_dbg(xhci, "%s called for udev %p\n", __func__, udev);
>>>  	virt_dev = xhci->devs[udev->slot_id];
>>>  
>>> +	if (xhci->quirks & XHCI_MTK_HOST) {
>>> +		ret = xhci_mtk_check_bandwidth(hcd, udev);
>>> +		if (ret < 0)
>>> +			return ret;
>>> +	}
>>> +
>>
>> Just noticed that XHCI_MTK_HOST quirk is only set in xhci-mtk.c.
>> xhci-mtk.c calls xhci_init_driver(..., xhci_mtk_overrides) with a .reset override function.
>>
>> why not add override functions for .check_bandwidth and .reset_bandwidth to xhci_mtk_overrides instead?
>>
>> Another patch to add similar overrides for .add_endpoint and .drop_endpoint should probably be
>> done so that we can get rid of the xhci_mtk_add/drop_ep_quirk() calls in xhci.c as well
> You mean, we can export xhci_add/drop_endpoint()?

I think so, unless you have a better idea.
I prefer exporting the generic add/drop_endpoint functions rather than the vendor specific quirk functions.

-Mathias