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Mon, 09 Nov 2020 10:05:37 +0100 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 344AB10002A; Mon, 9 Nov 2020 10:05:37 +0100 (CET) Received: from Webmail-eu.st.com (sfhdag3node1.st.com [10.75.127.7]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 263C1230468; Mon, 9 Nov 2020 10:05:37 +0100 (CET) Received: from lmecxl0889.lme.st.com (10.75.127.49) by SFHDAG3NODE1.st.com (10.75.127.7) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 9 Nov 2020 10:05:36 +0100 Subject: Re: [PATCH v2 08/14] remoteproc: Introduce function rproc_detach() To: Mathieu Poirier , "ohad@wizery.com" , "bjorn.andersson@linaro.org" CC: "linux-remoteproc@vger.kernel.org" References: <20201030195713.1366341-1-mathieu.poirier@linaro.org> <20201030195713.1366341-9-mathieu.poirier@linaro.org> From: Arnaud POULIQUEN Message-ID: <807cebaa-2d64-401a-d673-8f40b919924e@st.com> Date: Mon, 9 Nov 2020 10:05:35 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201030195713.1366341-9-mathieu.poirier@linaro.org> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.75.127.49] X-ClientProxiedBy: SFHDAG1NODE2.st.com (10.75.127.2) To SFHDAG3NODE1.st.com (10.75.127.7) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.312,18.0.737 definitions=2020-11-09_02:2020-11-05,2020-11-09 signatures=0 Precedence: bulk List-ID: X-Mailing-List: linux-remoteproc@vger.kernel.org Hi Mathieu, On 10/30/20 8:57 PM, Mathieu Poirier wrote: > Introduce function rproc_detach() to enable the remoteproc > core to release the resources associated with a remote processor > without stopping its operation. > > Signed-off-by: Mathieu Poirier > Reviewed-by: Peng Fan > --- > drivers/remoteproc/remoteproc_core.c | 65 +++++++++++++++++++++++++++- > include/linux/remoteproc.h | 1 + > 2 files changed, 65 insertions(+), 1 deletion(-) > > diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c > index 62e88ff65009..6b33a83960d2 100644 > --- a/drivers/remoteproc/remoteproc_core.c > +++ b/drivers/remoteproc/remoteproc_core.c > @@ -1667,7 +1667,7 @@ static int rproc_stop(struct rproc *rproc, bool crashed) > /* > * __rproc_detach(): Does the opposite of rproc_attach() > */ > -static int __maybe_unused __rproc_detach(struct rproc *rproc) > +static int __rproc_detach(struct rproc *rproc) > { > struct device *dev = &rproc->dev; > int ret; > @@ -1910,6 +1910,69 @@ void rproc_shutdown(struct rproc *rproc) > } > EXPORT_SYMBOL(rproc_shutdown); > > +/** > + * rproc_detach() - Detach the remote processor from the > + * remoteproc core > + * > + * @rproc: the remote processor > + * > + * Detach a remote processor (previously attached to with rproc_actuate()). > + * > + * In case @rproc is still being used by an additional user(s), then > + * this function will just decrement the power refcount and exit, > + * without disconnecting the device. > + * > + * Function rproc_detach() calls __rproc_detach() in order to let a remote > + * processor know that services provided by the application processor are > + * no longer available. From there it should be possible to remove the > + * platform driver and even power cycle the application processor (if the HW > + * supports it) without needing to switch off the remote processor. > + */ > +int rproc_detach(struct rproc *rproc) > +{ > + struct device *dev = &rproc->dev; > + int ret; > + > + ret = mutex_lock_interruptible(&rproc->lock); > + if (ret) { > + dev_err(dev, "can't lock rproc %s: %d\n", rproc->name, ret); > + return ret; > + } > + > + if (rproc->state != RPROC_RUNNING && rproc->state != RPROC_ATTACHED) { > + ret = -EPERM; > + goto out; > + } > + > + /* if the remote proc is still needed, bail out */ > + if (!atomic_dec_and_test(&rproc->power)) { > + ret = -EBUSY; > + goto out; > + } > + > + ret = __rproc_detach(rproc); > + if (ret) { > + atomic_inc(&rproc->power); > + goto out; > + } > + > + /* clean up all acquired resources */ > + rproc_resource_cleanup(rproc); > + > + rproc_disable_iommu(rproc); I'm not an IOMMU expert,so maybe this remark is not relevant... As IOMMU manage the access of the remote device to its memory, could this lead to a remote device crash? Regards, Arnaud > + > + /* > + * Set the remote processor's table pointer to NULL. Since mapping > + * of the resource table to a virtual address is done in the platform > + * driver, unmapping should also be done there. > + */ > + rproc->table_ptr = NULL; > +out: > + mutex_unlock(&rproc->lock); > + return ret; > +} > +EXPORT_SYMBOL(rproc_detach); > + > /** > * rproc_get_by_phandle() - find a remote processor by phandle > * @phandle: phandle to the rproc > diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h > index 3faff9bb4fb8..6713faab6959 100644 > --- a/include/linux/remoteproc.h > +++ b/include/linux/remoteproc.h > @@ -656,6 +656,7 @@ rproc_of_resm_mem_entry_init(struct device *dev, u32 of_resm_idx, size_t len, > > int rproc_boot(struct rproc *rproc); > void rproc_shutdown(struct rproc *rproc); > +int rproc_detach(struct rproc *rproc); > void rproc_report_crash(struct rproc *rproc, enum rproc_crash_type type); > int rproc_coredump_add_segment(struct rproc *rproc, dma_addr_t da, size_t size); > int rproc_coredump_add_custom_segment(struct rproc *rproc, >