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

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Date:   Thu, 7 Jan 2021 13:09:35 +0200
From:   Mathias Nyman <mathias.nyman@...ux.intel.com>
To:     Ikjoon Jang <ikjn@...omium.org>,
        linux-mediatek@...ts.infradead.org, linux-usb@...r.kernel.org
Cc:     Chunfeng Yun <chunfeng.yun@...iatek.com>,
        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 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

Thanks
-Mathias