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[104.57.184.186]) by smtp.gmail.com with ESMTPSA id q11sm1938274ota.54.2021.11.02.09.36.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Nov 2021 09:36:52 -0700 (PDT) Date: Tue, 2 Nov 2021 09:38:34 -0700 From: Bjorn Andersson To: Arnaud POULIQUEN Cc: Ohad Ben-Cohen , Mathieu Poirier , linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, julien.massot@iot.bzh Subject: Re: [PATCH v6 02/10] rpmsg: create the rpmsg class in core instead of in rpmsg char Message-ID: References: <20211022125426.2579-1-arnaud.pouliquen@foss.st.com> <20211022125426.2579-3-arnaud.pouliquen@foss.st.com> <962ca426-5cc4-4adb-df55-27fe93f7e767@foss.st.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <962ca426-5cc4-4adb-df55-27fe93f7e767@foss.st.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 02 Nov 08:23 PDT 2021, Arnaud POULIQUEN wrote: > > > On 11/1/21 5:57 PM, Bjorn Andersson wrote: > > On Fri 22 Oct 07:54 CDT 2021, Arnaud Pouliquen wrote: > > > >> Migrate the creation of the rpmsg class from the rpmsg_char > >> to the core that the class is usable by all rpmsg services. > >> > >> Suggested-by: Bjorn Andersson > >> Signed-off-by: Arnaud Pouliquen > >> --- > >> drivers/rpmsg/rpmsg_char.c | 14 ++------------ > >> drivers/rpmsg/rpmsg_core.c | 26 ++++++++++++++++++++++++-- > >> include/linux/rpmsg.h | 10 ++++++++++ > >> 3 files changed, 36 insertions(+), 14 deletions(-) > >> > >> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c > >> index 941c5c54dd72..327ed739a3a7 100644 > >> --- a/drivers/rpmsg/rpmsg_char.c > >> +++ b/drivers/rpmsg/rpmsg_char.c > >> @@ -28,7 +28,6 @@ > >> #define RPMSG_DEV_MAX (MINORMASK + 1) > >> > >> static dev_t rpmsg_major; > >> -static struct class *rpmsg_class; > >> > >> static DEFINE_IDA(rpmsg_ctrl_ida); > >> static DEFINE_IDA(rpmsg_ept_ida); > >> @@ -362,7 +361,7 @@ int rpmsg_chrdev_eptdev_create(struct rpmsg_device *rpdev, struct device *parent > >> init_waitqueue_head(&eptdev->readq); > >> > >> device_initialize(dev); > >> - dev->class = rpmsg_class; > >> + dev->class = rpmsg_get_class(); > >> dev->parent = parent; > >> dev->groups = rpmsg_eptdev_groups; > >> dev_set_drvdata(dev, eptdev); > >> @@ -482,7 +481,7 @@ static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev) > >> dev = &ctrldev->dev; > >> device_initialize(dev); > >> dev->parent = &rpdev->dev; > >> - dev->class = rpmsg_class; > >> + dev->class = rpmsg_get_class(); > >> > >> cdev_init(&ctrldev->cdev, &rpmsg_ctrldev_fops); > >> ctrldev->cdev.owner = THIS_MODULE; > >> @@ -558,17 +557,9 @@ static int rpmsg_chrdev_init(void) > >> return ret; > >> } > >> > >> - rpmsg_class = class_create(THIS_MODULE, "rpmsg"); > >> - if (IS_ERR(rpmsg_class)) { > >> - pr_err("failed to create rpmsg class\n"); > >> - unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX); > >> - return PTR_ERR(rpmsg_class); > >> - } > >> - > >> ret = register_rpmsg_driver(&rpmsg_chrdev_driver); > >> if (ret < 0) { > >> pr_err("rpmsgchr: failed to register rpmsg driver\n"); > >> - class_destroy(rpmsg_class); > >> unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX); > >> } > >> > >> @@ -579,7 +570,6 @@ postcore_initcall(rpmsg_chrdev_init); > >> static void rpmsg_chrdev_exit(void) > >> { > >> unregister_rpmsg_driver(&rpmsg_chrdev_driver); > >> - class_destroy(rpmsg_class); > >> unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX); > >> } > >> module_exit(rpmsg_chrdev_exit); > >> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c > >> index 9151836190ce..53162038254d 100644 > >> --- a/drivers/rpmsg/rpmsg_core.c > >> +++ b/drivers/rpmsg/rpmsg_core.c > >> @@ -20,6 +20,8 @@ > >> > >> #include "rpmsg_internal.h" > >> > >> +static struct class *rpmsg_class; > >> + > >> /** > >> * rpmsg_create_channel() - create a new rpmsg channel > >> * using its name and address info. > >> @@ -296,6 +298,19 @@ __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp, > >> } > >> EXPORT_SYMBOL(rpmsg_poll); > >> > >> +/** > >> + * rpmsg_get_class() - get reference to the sysfs rpmsg class > >> + * > >> + * This function return the pointer to the "rpmsg" class created by the rpmsg core. > >> + * > >> + * Returns the struct class pointer > >> + */ > >> +struct class *rpmsg_get_class(void) > > > > What value does this helper function add? Can't we just expose > > rpmsg_class directly? > > look to me cleaner to not expose directly the rpmsg_class in rpmsg.h as this > variable is read only for rpmsg services. > The pointer is read only, but the object isn't. So I think it's cleaner to just share the pointer in the first place. But that said, looking at this a little bit more, I don't think there's any guarantee that class_create() has been executed before rpmsg_ctrl_probe() is being invoked. > > > >> +{ > >> + return rpmsg_class; > >> +} > >> +EXPORT_SYMBOL(rpmsg_get_class); [..] > >> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h > > > > Isn't this just going to be used by rpmsg_char and rpmsg_ctrl? Do we > > really need to expose it in the client-facing API? > > I based this dev on hypothesis that the class could be used by some other rpmsg > clients. But it is not mandatory. It can be extended later, on need. > That's a good hypothesis, it might be useful in other places as well. But I think it's best to keep it local for now and make an explicit decision about opening up when that need comes. > What would you propose as an alternative to this API? > > I can see 2 alternatives: > - Define the rpmsg_class in rpmsg_internal.h > In current patchset rpmsg_char.c does not include the rpmsg_internal.h. > I'm not sure if this include makes sense for an rpmsg service driver. > rpmsg_ctrl and rpmsg_char are more tightly coupled to rpmsg than typical rpmsg drivers, so I think it's better to include rpmsg_internal.h than to open up the API to the clients. Thanks, Bjorn > - Use "extern struct class *rpmsg_class; " in rpmsg_char and rpmsg_ctrl modules > > Regards, > Arnaud > > > > > Regards, > > Bjorn > > > >> index a8dcf8a9ae88..6fe51549d931 100644 > >> --- a/include/linux/rpmsg.h > >> +++ b/include/linux/rpmsg.h > >> @@ -186,6 +186,8 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst, > >> __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp, > >> poll_table *wait); > >> > >> +struct class *rpmsg_get_class(void); > >> + > >> #else > >> > >> static inline int rpmsg_register_device(struct rpmsg_device *rpdev) > >> @@ -296,6 +298,14 @@ static inline __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, > >> return 0; > >> } > >> > >> +static inline struct class *rpmsg_get_class(void) > >> +{ > >> + /* This shouldn't be possible */ > >> + WARN_ON(1); > >> + > >> + return NULL; > >> +} > >> + > >> #endif /* IS_ENABLED(CONFIG_RPMSG) */ > >> > >> /* use a macro to avoid include chaining to get THIS_MODULE */ > >> -- > >> 2.17.1 > >>