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Tue, 9 Oct 2018 18:02:37 +0200 Subject: Re: [PATCH V4 0/4] Add TIOCM Signals support for RPMSG char devices To: Bjorn Andersson CC: Arun Kumar Neelakantam , , , , , References: <1538980699-21516-1-git-send-email-aneela@codeaurora.org> <20181008162325.GA1331@tuxbook-pro> From: Arnaud Pouliquen Openpgp: preference=signencrypt Autocrypt: addr=arnaud.pouliquen@st.com; prefer-encrypt=mutual; keydata= xsFNBFZu+HIBEAC/bt4pnj18oKkUw40q1IXSPeDFOuuznWgFbjFS6Mrb8axwtnxeYicv0WAL rWhlhQ6W2TfKDJtkDygkfaZw7Nlsj57zXrzjVXuy4Vkezxtg7kvSLYItQAE8YFSOrBTL58Yd d5cAFz/9WbWGRf0o9MxFavvGQ9zkfHVd+Ytw6dJNP4DUys9260BoxKZZMaevxobh5Hnram6M gVBYGMuJf5tmkXD/FhxjWEZ5q8pCfqZTlN9IZn7S8d0tyFL7+nkeYldA2DdVplfXXieEEURQ aBjcZ7ZTrzu1X/1RrH1tIQE7dclxk5pr2xY8osNePmxSoi+4DJzpZeQ32U4wAyZ8Hs0i50rS VxZuT2xW7tlNcw147w+kR9+xugXrECo0v1uX7/ysgFnZ/YasN8E+osM2sfa7OYUloVX5KeUK yT58KAVkjUfo0OdtSmGkEkILWQLACFEFVJPz7/I8PisoqzLS4Jb8aXbrwgIg7d4NDgW2FddV X9jd1odJK5N68SZqRF+I8ndttRGK0o7NZHH4hxJg9jvyEELdgQAmjR9Vf0eZGNfowLCnVcLq s+8q3nQ1RrW5cRBgB8YT2kC8wwY5as8fhfp4846pe2b8Akh0+Vba5pXaTvtmdOMRrcS7CtF6 Ogf9zKAxPZxTp0qGUOLE3PmSc3P3FQBLYa6Y+uS2v2iZTXljqQARAQABzSpBcm5hdWQgUG91 bGlxdWVuIDxhcm5hdWQucG91bGlxdWVuQHN0LmNvbT7CwX4EEwECACgFAlZu+HICGyMFCQlm AYAGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEP0ZQ+DAfqbfdXgP/RN0bU0gq3Pm1uAO 4LejmGbYeTi5OSKh7niuFthrlgUvzR4UxMbUBk30utQAd/FwYPHR81mE9N4PYEWKWMW0T3u0 5ASOBLpQeWj+edSE50jLggclVa4qDMl0pTfyLKOodt8USNB8aF0aDg5ITkt0euaGFaPn2kOZ QWVN+9a5O2MzNR3Sm61ojM2WPuB1HobbrCFzCT+VQDy4FLU0rsTjTanf6zpZdOeabt0LfWxF M69io06vzNSHYH91RJVl9mkIz7bYEZTBQR23KjLCsRXWfZ+54x6d6ITYZ2hp965PWuAhwWQr DdTJ3gPxmXJ7xK9+O15+DdUAbxF9FJXvvt9U5pTk3taTM3FIp/qaw77uxI/wniYA0dnIJRX0 o51sjR6cCO6hwLciO7+Q0OCDCbtStuKCCCTZY5bF6fuEqgybDwvLGAokYIdoMagJu1DLKu4p seKgPqGZ4vouTmEp6cWMzSyRz4pf3xIJc5McsdrUTN2LtcX63E45xKaj/n0Neft/Ce7OuyLB rr0ujOrVlWsLwyzpU5w5dX7bzkEW1Hp4mv44EDxH9zRiyI5dNPpLf57I83Vs/qP4bpy7/Hm1 fqbuM0wMbOquPGFI8fcYTkghntAAXMqNE6IvETzYqsPZwT0URpOzM9mho8u5+daFWWAuUXGA qRbo7qRs8Ev5jDsKBvGhzsFNBFZu+HIBEACrw5wF7Uf1h71YD5Jk7BG+57rpvnrLGk2s+YVW zmKsZPHT68SlMOy8/3gptJWgddHaM5xRLFsERswASmnJjIdPTOkSkVizfAjrFekZUr+dDZi2 3PrISz8AQBd+uJ29jRpeqViLiV+PrtCHnAKM0pxQ1BOv8TVlkfO7tZVduLJl5mVoz1sq3/C7 hT5ZICc2REWrfS24/Gk8mmtvMybiTMyM0QLFZvWyvNCvcGUS8s2a8PIcr+Xb3R9H0hMnYc2E 7bc5/e39f8oTbKI6xLLFLa5yJEVfTiVksyCkzpJSHo2eoVdW0lOtIlcUz1ICgZ7vVJg7chmQ nPmubeBMw73EyvagdzVeLm8Y/6Zux8SRab+ZcU/ZQWNPKoW5clUvagFBQYJ6I2qEoh2PqBI4 Wx0g1ca7ZIwjsIfWS7L3e310GITBsDmIeUJqMkfIAregf8KADPs4+L71sLeOXvjmdgTsHA8P lK8kUxpbIaTrGgHoviJ1IYwOvJBWrZRhdjfXTPl+ZFrJiB2E55XXogAAF4w/XHpEQNGkAXdQ u0o6tFkJutsJoU75aHPA4q/OvRlEiU6/8LNJeqRAR7oAvTexpO70f0Jns9GHzoy8sWbnp/LD BSH5iRCwq6Q0hJiEzrVTnO3bBp0WXfgowjXqR+YR86JPrzw2zjgr1e2zCZ1gHBTOyJZiDwAR AQABwsFlBBgBAgAPBQJWbvhyAhsMBQkJZgGAAAoJEP0ZQ+DAfqbfs5AQAJKIr2+j+U3JaMs3 px9bbxcuxRLtVP5gR3FiPR0onalO0QEOLKkXb1DeJaeHHxDdJnVV7rCJX/Fz5CzkymUJ7GIO gpUGstSpJETi2sxvYvxfmTvE78D76rM5duvnGy8lob6wR2W3IqIRwmd4X0Cy1Gtgo+i2plh2 ttVOM3OoigkCPY3AGD0ts+FbTn1LBVeivaOorezSGpKXy3cTKrEY9H5PC+DRJ1j3nbodC3o6 peWAlfCXVtErSQ17QzNydFDOysL1GIVn0+XY7X4Bq+KpVmhQOloEX5/At4FlhOpsv9AQ30rZ 3F5lo6FG1EqLIvg4FnMJldDmszZRv0bR0RM9Ag71J9bgwHEn8uS2vafuL1hOazZ0eAo7Oyup 2VNRC7Inbc+irY1qXSjmq3ZrD3SSZVa+LhYfijFYuEgKjs4s+Dvk/xVL0JYWbKkpGWRz5M82 Pj7co6u8pTEReGBYSVUBHx7GF1e3L/IMZZMquggEsixD8CYMOzahCEZ7UUwD5LKxRfmBWBgK 36tfTyducLyZtGB3mbJYfWeI7aiFgYsd5ehov6OIBlOz5iOshd97+wbbmziYEp6jWMIMX+Em zqSvS5ETZydayO5JBbw7fFBd1nGVYk1WL6Ll72g+iEnqgIckMtxey1TgfT7GhPkR7hl54ZAe 8mOik8I/F6EW8XyQAA2P Message-ID: Date: Tue, 9 Oct 2018 18:02:36 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20181008162325.GA1331@tuxbook-pro> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.75.127.45] X-ClientProxiedBy: SFHDAG8NODE2.st.com (10.75.127.23) To SFHDAG3NODE1.st.com (10.75.127.7) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-10-09_11:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org hello Bjorn, On 10/08/2018 06:23 PM, Bjorn Andersson wrote: > On Mon 08 Oct 06:08 PDT 2018, Arnaud Pouliquen wrote: > >> Hi Arun, Bjorn, >> >> On 10/08/2018 08:38 AM, Arun Kumar Neelakantam wrote: >>> Glink transport support signals to exchange state notification between >>> local and remote side clients. Adding support to send/receive the signal >>> command and notify the clients through callback and POLL notification. >> >> Please correct me if i'm wrong...My concern here is that this patchset >> implements a rpmsg service in the rpmsg core. I would separate this from >> the rpmsg core, as this is not part of the rpmsg protocol but seems >> linked to the serial protocol itself. >> Could it be implemented in rpmsg_char, using a dedicated channel...? >> > > rpmsg_char does expose a rpmsg channel (be it virtio, smd or glink) to > user space. This patch series add support for invoking TIOCMGET and > TIOCMSET on these channels. I'm not familiar with this concept, that could explain that i don't understand this patchset... TIOCMGET and TIOCMSET is related to the serial/console flow control, to control remote modem/processor, right? it seems be implemented only to support the rpmsg_char ioctl interface. When i have a look to the glink code, signal is treated by a message sent to remote processor. Therefore it seems that it could be treated as a service on top of rpmsg (so treat it in rpmsg_char instead of extend the rpmsg protocol to treat it in glink driver). > > In addition to adding the client side of this to rpmsg_char it provides > this support for glink, but the same mechanism exists in smd - while > this is not supported (today) by the virtio rpmsg. This is my main concern, i would like to be sure that this service is not related to specific needs introduced by the rmpsg char implementation: In this case this should not be part of the rpmsg core but perhaps some ops directly provided to the rpmsg_char on registration (rpmsg_chrdev_register_device?)... > > > I'm uncertain of how we could implement this mechanism for virtio rpmsg, > given that it as a transport doesn't really have a concept of > channels/flows - but it's really useful to have! > > PS. rpmsg_set_signals() can be called from any rpmsg device to perform > flow control of the communication channel. For my point of view this patch-set extends the rpmsg protocol to add channel flow control. Does it make sense to have a flow control in rpmsg protocol? if yes, should it be linked to a channel or to the remote processor itself? Extra comment: associated documentation update is missing. Regards, Arnaud > > Regards, > Bjorn > >> Regards >> Arnaud >> >>> >>> Changes since v1: >>> - Split the patches as per functional areas like core, char, glink >>> - Add set, clear mask for TIOCMSET >>> - Merge the char signal callback and POLLPRI patches >>> >>> Changes since v2: >>> - Modify the rpmsg_get_signals function prototype >>> >>> Changes since v3: >>> - Correct the TICOMGET case handling as per new rpmsg_get_signals prototype >>> - Update the rpmsg_get_signals function header >>> >>> Arun Kumar Neelakantam (4): >>> rpmsg: core: Add signal API support >>> rpmsg: glink: Add support to handle signals command >>> rpmsg: char: Add TIOCMGET/TIOCMSET ioctl support >>> rpmsg: char: Add signal callback and POLLPRI support >>> >>> drivers/rpmsg/qcom_glink_native.c | 126 ++++++++++++++++++++++++++++++++++++++ >>> drivers/rpmsg/rpmsg_char.c | 74 +++++++++++++++++++++- >>> drivers/rpmsg/rpmsg_core.c | 41 +++++++++++++ >>> drivers/rpmsg/rpmsg_internal.h | 5 ++ >>> include/linux/rpmsg.h | 26 ++++++++ >>> 5 files changed, 269 insertions(+), 3 deletions(-) >>>