linux-kernel - Re: [PATCH v2] drm/panthor: Simplify FW fast reset path

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Message-ID: <Zzy_qhXTZZrPwhHk@e110455-lin.cambridge.arm.com>
Date: Tue, 19 Nov 2024 16:41:14 +0000
From: Liviu Dudau <liviu.dudau@....com>
To: Boris Brezillon <boris.brezillon@...labora.com>
Cc: Karunika Choo <karunika.choo@....com>, nd@....com,
	Steven Price <steven.price@....com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] drm/panthor: Simplify FW fast reset path

On Tue, Nov 19, 2024 at 03:25:25PM +0100, Boris Brezillon wrote:
> On Tue, 19 Nov 2024 13:50:29 +0000
> Karunika Choo <karunika.choo@....com> wrote:
> 
> > Stop checking the FW halt_status as MCU_STATUS should be sufficient.
> > This should make the check for successful FW halt and subsequently
> > setting fast_reset to true more robust.
> > 
> > We should also clear GLB_REQ.GLB_HALT bit only on post-reset prior
> > to starting the FW and only if we're doing a fast reset, because
> > the slow reset will re-initialize all FW sections, including the
> > global interface.
> > 
> > Signed-off-by: Karunika Choo <karunika.choo@....com>
> 
> Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>
> 
> and I think you forgot to add Liviu's R-b

I've fixed the commit and pushed it without compile testing it because I did
it for the patch before it. Obviously it doesn't compile because glb_iface is
not defined :(

Adding a new patch, can you guys R-b this?

diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
index 4bc52b1b1a286..c807b6ce71bd4 100644
--- a/drivers/gpu/drm/panthor/panthor_fw.c
+++ b/drivers/gpu/drm/panthor/panthor_fw.c
@@ -1133,6 +1133,7 @@ int panthor_fw_post_reset(struct panthor_device *ptdev)
                 * This is not needed on a slow reset because FW sections are
                 * re-initialized.
                 */
+               struct panthor_fw_global_iface *glb_iface = panthor_fw_get_glb_iface(ptdev);
                panthor_fw_update_reqs(glb_iface, req, 0, GLB_HALT);
 
                ret = panthor_fw_start(ptdev);


Best regards,
Liviu

> 
> > ---
> > v2:
> > - clarify comments and commit message with regards to when to clear the
> >   GLB_HALT flag.
> > 
> >  drivers/gpu/drm/panthor/panthor_fw.c | 15 ++++++++-------
> >  1 file changed, 8 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> > index ecca5565ce41..4bc52b1b1a28 100644
> > --- a/drivers/gpu/drm/panthor/panthor_fw.c
> > +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> > @@ -1098,17 +1098,11 @@ void panthor_fw_pre_reset(struct panthor_device *ptdev, bool on_hang)
> >  		panthor_fw_update_reqs(glb_iface, req, GLB_HALT, GLB_HALT);
> >  		gpu_write(ptdev, CSF_DOORBELL(CSF_GLB_DOORBELL_ID), 1);
> >  		if (!readl_poll_timeout(ptdev->iomem + MCU_STATUS, status,
> > -					status == MCU_STATUS_HALT, 10, 100000) &&
> > -		    glb_iface->output->halt_status == PANTHOR_FW_HALT_OK) {
> > +					status == MCU_STATUS_HALT, 10, 100000)) {
> >  			ptdev->fw->fast_reset = true;
> >  		} else {
> >  			drm_warn(&ptdev->base, "Failed to cleanly suspend MCU");
> >  		}
> > -
> > -		/* The FW detects 0 -> 1 transitions. Make sure we reset
> > -		 * the HALT bit before the FW is rebooted.
> > -		 */
> > -		panthor_fw_update_reqs(glb_iface, req, 0, GLB_HALT);
> >  	}
> >  
> >  	panthor_job_irq_suspend(&ptdev->fw->irq);
> > @@ -1134,6 +1128,13 @@ int panthor_fw_post_reset(struct panthor_device *ptdev)
> >  	 * the FW sections. If it fails, go for a full reset.
> >  	 */
> >  	if (ptdev->fw->fast_reset) {
> > +		/* The FW detects 0 -> 1 transitions. Make sure we reset
> > +		 * the HALT bit before the FW is rebooted.
> > +		 * This is not needed on a slow reset because FW sections are
> > +		 * re-initialized.
> > +		 */
> > +		panthor_fw_update_reqs(glb_iface, req, 0, GLB_HALT);
> > +
> >  		ret = panthor_fw_start(ptdev);
> >  		if (!ret)
> >  			goto out;
> 

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    ¯\_(ツ)_/¯