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[71.195.29.92]) by smtp.googlemail.com with ESMTPSA id q24sm6851957ioh.31.2019.05.21.04.03.58 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 21 May 2019 04:03:59 -0700 (PDT) Subject: Re: [PATCH 1/8] net: qualcomm: rmnet: fix struct rmnet_map_header To: Bjorn Andersson Cc: Subash Abhinov Kasiviswanathan , arnd@arndb.de, david.brown@linaro.org, agross@kernel.org, davem@davemloft.net, ilias.apalodimas@linaro.org, cpratapa@codeaurora.org, syadagir@codeaurora.org, evgreen@chromium.org, benchan@google.com, ejcaruso@google.com, netdev@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20190520135354.18628-1-elder@linaro.org> <20190520135354.18628-2-elder@linaro.org> <81fd1e01-b8e3-f86a-fcc9-2bcbc51bd679@linaro.org> <20190521030712.GY2085@tuxbook-pro> From: Alex Elder Message-ID: <25b1d768-d492-08a7-b1ab-d3d022b01bc9@linaro.org> Date: Tue, 21 May 2019 06:03:58 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190521030712.GY2085@tuxbook-pro> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 5/20/19 10:07 PM, Bjorn Andersson wrote: > On Mon 20 May 19:30 PDT 2019, Alex Elder wrote: > >> On 5/20/19 8:32 PM, Subash Abhinov Kasiviswanathan wrote: >>>> >>>> If you are telling me that the command/data flag resides at bit >>>> 7 of the first byte, I will update the field masks in a later >>>> patch in this series to reflect that. >>>> >>> >>> Higher order bit is Command / Data. >> >> So what this means is that to get the command/data bit we use: >> >> first_byte & 0x80 >> >> If that is correct I will remove this patch from the series and >> will update the subsequent patches so bit 7 is the command bit, >> bit 6 is reserved, and bits 0-5 are the pad length. >> >> I will post a v2 of the series with these changes, and will >> incorporate Bjorn's "Reviewed-by". >> > > But didn't you say that your testing show that the current bit order is > wrong? I did say that, but it seems I may have been misinterpreting what the documentation said, namely that "bit 0" in the network data stream is actually the high-order bit in the first byte. I did definitely see that bit 7 (0x80) in the first byte was the one selected by the "cd_bit" C bit-field originally, and I believed that was wrong. The other thing I can say is that I never see that bit set in my use of the rmnet driver for IPA. On top of that, the pad_len value is 0. Given that, either bit order works, because the whole first byte is 0 either way. So it turns out the testing I am able to do is not adequate to verify the change. I am hoping that Subash has an environment in which QMAP commands (with the appropriate bit set) are actually used. I'm going to wait a bit for him to confirm that, but at this time my plan is to do as I said above--remove this patch and adjust the ones that follow accordingly. -Alex > I still like the cleanup, if nothing else just to clarify and clearly > document the actual content of this header. > > Regards, > Bjorn >