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[68.147.0.187]) by smtp.gmail.com with ESMTPSA id a9sm9877030pfn.178.2021.01.22.12.59.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 Jan 2021 12:59:36 -0800 (PST) Date: Fri, 22 Jan 2021 13:59:34 -0700 From: Mathieu Poirier To: Arnaud POULIQUEN Cc: Bjorn Andersson , Ohad Ben-Cohen , Andy Gross , linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-msm@vger.kernel.org Subject: Re: [PATCH v2 04/16] rpmsg: ctrl: implement the ioctl function to create device Message-ID: <20210122205934.GA866146@xps15> References: <20201222105726.16906-1-arnaud.pouliquen@foss.st.com> <20201222105726.16906-5-arnaud.pouliquen@foss.st.com> <20210121235258.GG611676@xps15> <1b76bf93-9647-c658-b4dd-1b10264a1189@foss.st.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1b76bf93-9647-c658-b4dd-1b10264a1189@foss.st.com> Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Fri, Jan 22, 2021 at 02:05:27PM +0100, Arnaud POULIQUEN wrote: > Hi Mathieu, > > On 1/22/21 12:52 AM, Mathieu Poirier wrote: > > On Tue, Dec 22, 2020 at 11:57:14AM +0100, Arnaud Pouliquen wrote: > >> Implement the ioctl function that parses the list of > >> rpmsg drivers registered to create an associated device. > >> To be ISO user API, in a first step, the driver_override > >> is only allowed for the RPMsg raw service, supported by the > >> rpmsg_char driver. > >> > >> Signed-off-by: Arnaud Pouliquen > >> --- > >> drivers/rpmsg/rpmsg_ctrl.c | 43 ++++++++++++++++++++++++++++++++++++-- > >> 1 file changed, 41 insertions(+), 2 deletions(-) > >> > >> diff --git a/drivers/rpmsg/rpmsg_ctrl.c b/drivers/rpmsg/rpmsg_ctrl.c > >> index 065e2e304019..8381b5b2b794 100644 > >> --- a/drivers/rpmsg/rpmsg_ctrl.c > >> +++ b/drivers/rpmsg/rpmsg_ctrl.c > >> @@ -56,12 +56,51 @@ static int rpmsg_ctrl_dev_open(struct inode *inode, struct file *filp) > >> return 0; > >> } > >> > >> +static const char *rpmsg_ctrl_get_drv_name(u32 service) > >> +{ > >> + struct rpmsg_ctl_info *drv_info; > >> + > >> + list_for_each_entry(drv_info, &rpmsg_drv_list, node) { > >> + if (drv_info->ctrl->service == service) > >> + return drv_info->ctrl->drv_name; > >> + } > >> + > > > > I'm unsure about the above... To me this looks like what the .match() function > > of a bus would do. And when I read Bjorn's comment he brought up the > > auxiliary_bus. I don't know about the auxiliary_bus but it is worth looking > > into. Registering with a bus would streamline a lot of the code in this > > patchset. > > As answered Bjorn, we already have the RPMsg bus to manage the rpmsg devices. > Look like duplication from my POV, except if the IOCTL does not manage channel > but only endpoint. > > In my design I considered that the rpmsg_ctrl creates a channel associated to a > rpmsg_device such as the RPMsg ns_announcement. > > Based on this assumption, if we implement the auxiliary_bus (or other) for the > rpmsg_ctrl a RPMsg driver will have to manage the probe by rpmsg_bus and by the > auxillary bus. The probe from the auxiliary bus would lead to the creation of an > RPMsg device on the rpmsg_bus, so a duplication with cross dependencies and > would probably make tricky the remove part. > > That said, I think the design depends on the functionality that should be > implemented in the rpmsg_ctrl. Here is an alternative approach based on the > auxiliary bus, which I'm starting to think about: > > The current approach of the rpmsg_char driver is to use the IOCTRL interface to > instantiate a cdev with an endpoint (the RPMsg device is associated with the > ioctl dev). This would correspond to the use of an auxiliary bus to manage local > endpoint creations. > > We could therefore consider an RPMsg name service based on an RPmsg device. This > RPMsg device would register a kind of "RPMsg service endpoint" driver on the > auxiliary rpmsg_ioctl bus. > The rpmsg_ctrl will be used to instantiate the endpoints for this RPMsg device. > on user application request the rpmsg_ctrl will call the appropriate auxiliary > device to create an endpoint. > > If we consider that one objective of this series is to allow application to > initiate the communication with the remote processor, so to be able to initiate > the service (ns announcement sent to the remote processor). > This implies that: > -either the RPMsg device has been probed first by a remote ns announcement or by > a Linux kernel driver using the "driver_override", to register an auxiliary > device. In this case an endpoint will be created associated to the RPMsg service > - or create a RPMsg device on first ioctl endpoint creation request, if it does > not exist (that could trig a NS announcement to remote processor). > > But I'm not sure that this approach would work with QCOM RPMsg backends... > I don't think there is a way forward with this set without a clear understanding of the Glink and SMD drivers. I have already spent a fair amount of time in the Glink driver and will continue on Monday with SMD. > > > > I'm out of time for today - I will continue tomorrow. > > It seems to me that the main point to step forward is to clarify the global > design and features of the rpmsg-ctrl. > Depending on the decision taken, this series could be trashed and rewritten from > a blank page...To not lost to much time on the series don't hesitate to limit > the review to the minimum. > I doubt you will ever get clear guidelines on the whole solution. I will get back to you once I am done with the SMD driver, which should be in the latter part of next week. > Thanks, > Arnaud > > > > > Thanks, > > Mathieu > > > >> + return NULL; > >> +} > >> + > >> static long rpmsg_ctrl_dev_ioctl(struct file *fp, unsigned int cmd, > >> unsigned long arg) > >> { > >> struct rpmsg_ctrl_dev *ctrldev = fp->private_data; > >> - > >> - dev_info(&ctrldev->dev, "Control not yet implemented\n"); > >> + void __user *argp = (void __user *)arg; > >> + struct rpmsg_channel_info chinfo; > >> + struct rpmsg_endpoint_info eptinfo; > >> + struct rpmsg_device *newch; > >> + > >> + if (cmd != RPMSG_CREATE_EPT_IOCTL) > >> + return -EINVAL; > >> + > >> + if (copy_from_user(&eptinfo, argp, sizeof(eptinfo))) > >> + return -EFAULT; > >> + > >> + /* > >> + * In a frst step only the rpmsg_raw service is supported. > >> + * The override is foorced to RPMSG_RAW_SERVICE > >> + */ > >> + chinfo.driver_override = rpmsg_ctrl_get_drv_name(RPMSG_RAW_SERVICE); > >> + if (!chinfo.driver_override) > >> + return -ENODEV; > >> + > >> + memcpy(chinfo.name, eptinfo.name, RPMSG_NAME_SIZE); > >> + chinfo.name[RPMSG_NAME_SIZE - 1] = '\0'; > >> + chinfo.src = eptinfo.src; > >> + chinfo.dst = eptinfo.dst; > >> + > >> + newch = rpmsg_create_channel(ctrldev->rpdev, &chinfo); > >> + if (!newch) { > >> + dev_err(&ctrldev->dev, "rpmsg_create_channel failed\n"); > >> + return -ENXIO; > >> + } > >> > >> return 0; > >> }; > >> -- > >> 2.17.1 > >>