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[73.185.129.58]) by smtp.googlemail.com with ESMTPSA id u11sm913650iol.51.2020.12.02.05.24.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 02 Dec 2020 05:24:22 -0800 (PST) Subject: Re: [PATCH net-next 2/2] net: ipa: add support for inline checksum offload To: Jakub Kicinski Cc: davem@davemloft.net, evgreen@chromium.org, cpratapa@codeaurora.org, bjorn.andersson@linaro.org, subashab@codeaurora.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20201201004143.27569-1-elder@linaro.org> <20201201004143.27569-3-elder@linaro.org> <20201201181319.41091a37@kicinski-fedora-pc1c0hjn.DHCP.thefacebook.com> From: Alex Elder Message-ID: Date: Wed, 2 Dec 2020 07:24:21 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <20201201181319.41091a37@kicinski-fedora-pc1c0hjn.DHCP.thefacebook.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/1/20 8:13 PM, Jakub Kicinski wrote: >> To function, the rmnet driver must also add support for this new >> "inline" checksum offload. The changes implementing this will be >> submitted soon. > We don't usually merge half of a feature. Why not wait until all > support is in place? > > Do I understand right that it's rmnet that will push the csum header? > This change seems to only reserve space for it and request the feature > at init.. You are correct. The IPA hardware needs to be programmed to perform the computation and verify that the checksum in the header matches what it computes (for AP RX offload), or insert it into the header (for AP TX offload). That's what this patch handles. The RMNet driver is responsible for stripping the offload header off on RX, and acting on what it says (i.e., whether hardware is able to state the checksum is good). And on TX it inserts an offload header that says what to checksum and where to put it in the packet. It's totally fine not to merge this until we have the whole package ready, I understand. I'll see what I can do to get that done quickly. Thanks Jakub. -Alex