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Wed, 20 Dec 2023 10:40:54 +0000 (UTC) Message-ID: <4117de24-75fd-4355-9ffb-7d1bc0167295@collabora.com> Date: Wed, 20 Dec 2023 11:40:54 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/3] dt-bindings: usb: mtk-xhci: add a property for Gen1 isoc-in transfer issue Content-Language: en-US To: Krzysztof Kozlowski , Chunfeng Yun , Greg Kroah-Hartman , Rob Herring , Krzysztof Kozlowski Cc: Conor Dooley , Matthias Brugger , Mathias Nyman , linux-usb@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Eddie Hung , Macpaul Lin References: <20231220025842.7082-1-chunfeng.yun@mediatek.com> From: AngeloGioacchino Del Regno In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231220_024100_447696_DB05C457 X-CRM114-Status: GOOD ( 17.97 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Il 20/12/23 08:38, Krzysztof Kozlowski ha scritto: > On 20/12/2023 03:58, Chunfeng Yun wrote: >> For Gen1 isoc-in endpoint on controller before about SSUSB IPM v1.6.0, it >> still send out unexpected ACK after receiving a short packet in burst >> transfer, this will cause an exception on connected device, specially for >> a 4k camera. >> Add a quirk property "rx-fifo-depth" to work around this hardware issue, >> prefer to use 3k bytes; >> The side-effect is that may cause performance drop about 10%, including >> bulk transfer. >> >> Signed-off-by: Chunfeng Yun >> --- >> v3: add fifo depth unit, change the value range from 0-3 to 1-4 >> v2: change 'mediatek,rxfifo-depth' to 'rx-fifo-depth' >> --- >> .../devicetree/bindings/usb/mediatek,mtk-xhci.yaml | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) >> >> diff --git a/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml b/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml >> index e9644e333d78..9478b7031796 100644 >> --- a/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml >> +++ b/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml >> @@ -124,6 +124,18 @@ properties: >> defined in the xHCI spec on MTK's controller. >> default: 5000 >> >> + rx-fifo-depth: >> + $ref: /schemas/types.yaml#/definitions/uint32 >> + description: >> + It is a quirk used to work around Gen1 isoc-in endpoint transfer issue >> + that still send out unexpected ACK after device finish the burst transfer >> + with a short packet and cause an exception, specially on a 4K camera >> + device, it happens on controller before about IPM v1.6.0; the side-effect >> + is that may cause performance drop about 10%, include bulk transfer, >> + prefer to use 3 here. The unit is 1K bytes. > > NAK. Read comments on previous submission. > > Best regards, > Krzysztof > Chunfeng, I think the discussion was not clear for you, so I will try to give you a different explanation: this should be expressed in bytes, so 1000, or 1024, 2048, 4096, etc, and not 1/2/3/4/5/n. The driver shall then validate and map your bytes number to hardware register value and subsequently write to the registers. Cheers, Angleo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel