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[104.188.17.28]) by smtp.gmail.com with ESMTPSA id q15sm3625663pgi.55.2020.01.23.09.15.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Jan 2020 09:15:28 -0800 (PST) Date: Thu, 23 Jan 2020 09:15:24 -0800 From: Bjorn Andersson To: Mathieu Poirier Cc: Rob Herring , Mark Rutland , Ohad Ben-Cohen , linux-arm-msm , devicetree@vger.kernel.org, Linux Kernel Mailing List , linux-remoteproc , Sibi Sankar , Rishabh Bhatnagar Subject: Re: [PATCH v2 7/8] remoteproc: qcom: q6v5: Add common panic handler Message-ID: <20200123171524.GV1511@yoga> References: <20191227053215.423811-1-bjorn.andersson@linaro.org> <20191227053215.423811-8-bjorn.andersson@linaro.org> <20200110212806.GD11555@xps15> <20200122193936.GB3261042@ripper> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 23 Jan 09:01 PST 2020, Mathieu Poirier wrote: > On Wed, 22 Jan 2020 at 12:40, Bjorn Andersson > wrote: > > > > On Fri 10 Jan 13:28 PST 2020, Mathieu Poirier wrote: > > > > > On Thu, Dec 26, 2019 at 09:32:14PM -0800, Bjorn Andersson wrote: > > > > Add a common panic handler that invokes a stop request and sleep enough > > > > to let the remoteproc flush it's caches etc in order to aid post mortem > > > > debugging. > > > > > > > > Signed-off-by: Bjorn Andersson > > > > --- > > > > > > > > Changes since v1: > > > > - None > > > > > > > > drivers/remoteproc/qcom_q6v5.c | 19 +++++++++++++++++++ > > > > drivers/remoteproc/qcom_q6v5.h | 1 + > > > > 2 files changed, 20 insertions(+) > > > > > > > > diff --git a/drivers/remoteproc/qcom_q6v5.c b/drivers/remoteproc/qcom_q6v5.c > > > > index cb0f4a0be032..17167c980e02 100644 > > > > --- a/drivers/remoteproc/qcom_q6v5.c > > > > +++ b/drivers/remoteproc/qcom_q6v5.c > > > > @@ -6,6 +6,7 @@ > > > > * Copyright (C) 2014 Sony Mobile Communications AB > > > > * Copyright (c) 2012-2013, The Linux Foundation. All rights reserved. > > > > */ > > > > +#include > > > > #include > > > > #include > > > > #include > > > > @@ -15,6 +16,8 @@ > > > > #include > > > > #include "qcom_q6v5.h" > > > > > > > > +#define Q6V5_PANIC_DELAY_MS 200 > > > > + > > > > /** > > > > * qcom_q6v5_prepare() - reinitialize the qcom_q6v5 context before start > > > > * @q6v5: reference to qcom_q6v5 context to be reinitialized > > > > @@ -162,6 +165,22 @@ int qcom_q6v5_request_stop(struct qcom_q6v5 *q6v5) > > > > } > > > > EXPORT_SYMBOL_GPL(qcom_q6v5_request_stop); > > > > > > > > +/** > > > > + * qcom_q6v5_panic() - panic handler to invoke a stop on the remote > > > > + * @q6v5: reference to qcom_q6v5 context > > > > + * > > > > + * Set the stop bit and sleep in order to allow the remote processor to flush > > > > + * its caches etc for post mortem debugging. > > > > + */ > > > > +void qcom_q6v5_panic(struct qcom_q6v5 *q6v5) > > > > +{ > > > > + qcom_smem_state_update_bits(q6v5->state, > > > > + BIT(q6v5->stop_bit), BIT(q6v5->stop_bit)); > > > > + > > > > + mdelay(Q6V5_PANIC_DELAY_MS); > > > > > > I really wonder if the delay should be part of the remoteproc core and > > > configurable via device tree. Wanting the remote processor to flush its caches > > > is likely something other vendors will want when dealing with a kernel panic. > > > It would be nice to see if other people have an opinion on this topic. If not > > > then we can keep the delay here and move it to the core if need be. > > > > > > > I gave this some more thought and what we're trying to achieve is to > > signal the remote processors about the panic and then give them time to > > react, but per the proposal (and Qualcomm downstream iirc) we will do > > this for each remote processor, one by one. > > > > So in the typical case of a Qualcomm platform with 4-5 remoteprocs we'll > > end up giving the first one a whole second to react and the last one > > "only" 200ms. > > > > Moving the delay to the core by iterating over rproc_list calling > > panic() and then delaying would be cleaner imo. > > I agree. > > > > > It might be nice to make this configurable in DT, but I agree that it > > would be nice to hear from others if this would be useful. > > I think the delay has to be configurable via DT if we move this to the > core. The binding can be optional and default to 200ms if not > present. > How about I make the panic() return the required delay and then we let the core sleep for MAX() of the returned durations? That way the default is still a property of the remoteproc drivers - and 200ms seems rather arbitrary to put in the core, even as a default. Regards, Bjorn