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[195.231.47.232]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49fe5b9c59dsm52797735e9.1.2026.09.24.03.24.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 24 Sep 2026 03:24:07 -0700 (PDT) Message-ID: <4d5e2857-e6eb-43e2-b668-83e779aaa734@redhat.com> Date: Thu, 24 Sep 2026 12:24:06 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] net: usb: cdc_mbim: add MeiG Smart SRM821 to ZLP whitelist To: Ming Wang , netdev@vger.kernel.org Cc: linux-usb@vger.kernel.org, stable@vger.kernel.org, Oliver Neukum , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , linux-kernel@vger.kernel.org References: <20260920074500.826121-1-wangming01@loongson.cn> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20260920074500.826121-1-wangming01@loongson.cn> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 9/20/26 09:44, Ming Wang wrote: > The MeiG Smart SRM821 5G module (0x2dee:0x4d53) crashes and drops off > the USB bus when it receives a Zero Length Packet (ZLP) after sending > or receiving an NTB of exactly 16384 bytes (tx_max). > > According to the MBIM specification, devices do not require a ZLP > if the NTB size is exactly dwNtbOutMaxSize. However, the cdc_mbim > driver defaults to sending ZLPs for devices not explicitly whitelisted > to accommodate non-conformant hardware. This default behavior breaks > the strictly conformant MeiG SRM821 module. > > Add this device to the ZLP conformance whitelist (cdc_mbim_info) so > the driver will pad the NTB to avoid sending ZLPs, preventing the > device firmware from crashing. > > Cc: stable@vger.kernel.org > Signed-off-by: Ming Wang Before any other step, please read: https://elixir.bootlin.com/linux/v7.3-rc3/source/Documentation/process/maintainer-netdev.rst#L454 AFAICS this is actually support for additional H/W, just worded in very unusual way: please reword the commit message accordingly and drop stable from CC. /P