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Message-ID: <7c388791-e4cd-28da-3d98-5cc233bec165@linux.intel.com>
Date:   Tue, 12 Sep 2023 14:33:20 +0300
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Subject: Re: [PATCH] usb: xhci: xhci-ring: Use sysdev for mapping bounce
 buffer
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To:     Wesley Cheng <quic_wcheng@quicinc.com>, mathias.nyman@intel.com,
        gregkh@linuxfoundation.org
Cc:     linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
        quic_jackp@quicinc.com, stable@vger.kernel.org
References: <20230911234122.1408-1-quic_wcheng@quicinc.com>
From:   Mathias Nyman <mathias.nyman@linux.intel.com>
In-Reply-To: <20230911234122.1408-1-quic_wcheng@quicinc.com>
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On 12.9.2023 2.41, Wesley Cheng wrote:
> As mentioned in:
>    commit 474ed23a6257 ("xhci: align the last trb before link if it is
> easily splittable.")
> 
> A bounce buffer is utilized for ensuring that transfers that span across
> ring segments are aligned to the EP's max packet size.  However, the device
> that is used to map the DMA buffer to is currently using the XHCI HCD,
> which does not carry any DMA operations in certain configrations.
> Migration to using the sysdev entry was introduced for DWC3 based
> implementations where the IOMMU operations are present.
> 
> Replace the reference to the controller device to sysdev instead.  This
> allows the bounce buffer to be properly mapped to any implementations that
> have an IOMMU involved.
> 
> cc: <stable@vger.kernel.org>
> Fixes: 4c39d4b949d3 ("usb: xhci: use bus->sysdev for DMA configuration")
> Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
> ---

Thanks, adding to queue

-Mathias