linux-kernel - Re: [PATCH 1/4] remoteproc: k3-r5: Fix IPC-only mode detection

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Message-ID: <CANLsYkxFvci0o0ET4vOGTYp0P2xEdwU2q4V1SmNh=W83uj87rA@mail.gmail.com>
Date: Fri, 28 Jun 2024 13:58:31 -0600
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: Nishanth Menon <nm@...com>, Vignesh Raghavendra <vigneshr@...com>, Hari Nagalla <hnagalla@...com>, 
	"Andrew F. Davis" <afd@...com>
Cc: Bjorn Andersson <andersson@...nel.org>, Philipp Zabel <p.zabel@...gutronix.de>, 
	Suman Anna <s-anna@...com>, Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
	Alexandre Belloni <alexandre.belloni@...tlin.com>, Udit Kumar <u-kumar1@...com>, 
	Thomas Richard <thomas.richard@...tlin.com>, Gregory CLEMENT <gregory.clement@...tlin.com>, 
	Théo Lebrun <theo.lebrun@...tlin.com>, 
	linux-remoteproc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] remoteproc: k3-r5: Fix IPC-only mode detection

Nishanth, Vignesh, Hari and Andrew - please have a look at this patch.

Thanks,
Mathieu

On Fri, 28 Jun 2024 at 13:53, Mathieu Poirier
<mathieu.poirier@...aro.org> wrote:
>
> Good day,
>
> On Fri, Jun 21, 2024 at 05:00:55PM +0200, Richard Genoud wrote:
> > ret variable was used to test reset status, get from
> > reset_control_status() call. But this variable was overwritten by
> > ti_sci_proc_get_status() a few lines bellow.
> > And as ti_sci_proc_get_status() returns 0 or a negative value (in this
> > latter case, followed by a return), the expression !ret was always true,
> >
> > Clearly, this was not what was intended:
> > In the comment above it's said that "requires both local and module
> > resets to be deasserted"; if reset_control_status() returns 0 it means
> > that the reset line is deasserted.
> > So, it's pretty clear that the return value of reset_control_status()
> > was intended to be used instead of ti_sci_proc_get_status() return
> > value.
> >
> > This could lead in an incorrect IPC-only mode detection if reset line is
> > asserted (so reset_control_status() return > 0) and c_state != 0 and
> > halted == 0.
> > In this case, the old code would have detected an IPC-only mode instead
> > of a mismatched mode.
> >
>
> Your assessment seems to be correct.  That said I'd like to have an RB or a TB
> from someone in the TI delegation - guys please have a look.
>
> Thanks,
> Mathieu
>
> > Fixes: 1168af40b1ad ("remoteproc: k3-r5: Add support for IPC-only mode for all R5Fs")
> > Signed-off-by: Richard Genoud <richard.genoud@...tlin.com>
> > ---
> >  drivers/remoteproc/ti_k3_r5_remoteproc.c | 13 +++++++------
> >  1 file changed, 7 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/remoteproc/ti_k3_r5_remoteproc.c b/drivers/remoteproc/ti_k3_r5_remoteproc.c
> > index 50e486bcfa10..39a47540c590 100644
> > --- a/drivers/remoteproc/ti_k3_r5_remoteproc.c
> > +++ b/drivers/remoteproc/ti_k3_r5_remoteproc.c
> > @@ -1144,6 +1144,7 @@ static int k3_r5_rproc_configure_mode(struct k3_r5_rproc *kproc)
> >       u32 atcm_enable, btcm_enable, loczrama;
> >       struct k3_r5_core *core0;
> >       enum cluster_mode mode = cluster->mode;
> > +     int reset_ctrl_status;
> >       int ret;
> >
> >       core0 = list_first_entry(&cluster->cores, struct k3_r5_core, elem);
> > @@ -1160,11 +1161,11 @@ static int k3_r5_rproc_configure_mode(struct k3_r5_rproc *kproc)
> >                        r_state, c_state);
> >       }
> >
> > -     ret = reset_control_status(core->reset);
> > -     if (ret < 0) {
> > +     reset_ctrl_status = reset_control_status(core->reset);
> > +     if (reset_ctrl_status < 0) {
> >               dev_err(cdev, "failed to get initial local reset status, ret = %d\n",
> > -                     ret);
> > -             return ret;
> > +                     reset_ctrl_status);
> > +             return reset_ctrl_status;
> >       }
> >
> >       /*
> > @@ -1199,7 +1200,7 @@ static int k3_r5_rproc_configure_mode(struct k3_r5_rproc *kproc)
> >        * irrelevant if module reset is asserted (POR value has local reset
> >        * deasserted), and is deemed as remoteproc mode
> >        */
> > -     if (c_state && !ret && !halted) {
> > +     if (c_state && !reset_ctrl_status && !halted) {
> >               dev_info(cdev, "configured R5F for IPC-only mode\n");
> >               kproc->rproc->state = RPROC_DETACHED;
> >               ret = 1;
> > @@ -1217,7 +1218,7 @@ static int k3_r5_rproc_configure_mode(struct k3_r5_rproc *kproc)
> >               ret = 0;
> >       } else {
> >               dev_err(cdev, "mismatched mode: local_reset = %s, module_reset = %s, core_state = %s\n",
> > -                     !ret ? "deasserted" : "asserted",
> > +                     !reset_ctrl_status ? "deasserted" : "asserted",
> >                       c_state ? "deasserted" : "asserted",
> >                       halted ? "halted" : "unhalted");
> >               ret = -EINVAL;