Hi Biju,
On Sat, Aug 27, 2022 at 04:07:56PM +0000, Biju Das wrote:
> > Subject: Re: [PATCH v13 2/5] media: renesas: vsp1: Add support to deassert/assert reset line
> > On Thu, Aug 25, 2022 at 02:21:41PM +0100, Biju Das wrote:
> > > As the resets DT property is mandatory, and is present in all .dtsi in
> > > mainline, add support to perform deassert/assert using reference
> > > counted reset handle.
> > >
> > > Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > > Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> > > Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> > > ---
> > > v12->v13:
> > > * Removed unused iopoll.h header file.
> > > * Added Rb tag from Geert.
> > > v11->v12:
> > > * Replaced read_poll_timeout_atomic-> udelay(1) as testing on RZ/G1N
> > > shows this delay is sufficient to avoid lock-up.
> > > * Removed Rb tags.
> > > v10->v11:
> > > * To avoid lock-up on R-Car Gen2, added poll for reset status after deassert.
> > > v9->v10:
> > > * Moved {deassert,assert} calls to vsp1_pm_runtime_{resume,suspend}
> > > v8->v9:
> > > * No change
> > > v7->v8:
> > > * No Change
> > > v6->v7:
> > > * No change
> > > v5->v6:
> > > * Rebased to media_staging and updated commit header
> > > * Added Rb tag from Laurent
> > > * Added forward declaration for struct reset_control
> > > * Updated vsp1_device_get() with changes suggested by Laurent
> > > * Updated error message for reset_control_get form ctrl->control.
> > > v4->v5:
> > > * Added Rb tag from Geert
> > > v3->v4:
> > > * Restored error check for pm_runtime_resume_and_get and calls
> > > assert() in case of failure.
> > > v2->v3:
> > > * Added Rb tag from Philipp
> > > * If reset_control_deassert() failed, return ret directly.
> > > v1->v2:
> > > * Used reference counted reset handle to perform deassert/assert
> > > RFC->v1:
> > > * Added reset support as separate patch
> > > * Moved rstc just after the bus_master field in struct vsp1_device
> > > RFC:
> > > *
> > > ---
> > > drivers/media/platform/renesas/vsp1/vsp1.h | 2 ++
> > > .../media/platform/renesas/vsp1/vsp1_drv.c | 28 +++++++++++++++++-
> > -
> > > 2 files changed, 28 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/media/platform/renesas/vsp1/vsp1.h
> > > b/drivers/media/platform/renesas/vsp1/vsp1.h
> > > index 37cf33c7e6ca..baf898d577ec 100644
> > > --- a/drivers/media/platform/renesas/vsp1/vsp1.h
> > > +++ b/drivers/media/platform/renesas/vsp1/vsp1.h
> > > @@ -22,6 +22,7 @@
> > > struct clk;
> > > struct device;
> > > struct rcar_fcp_device;
> > > +struct reset_control;
> > >
> > > struct vsp1_drm;
> > > struct vsp1_entity;
> > > @@ -79,6 +80,7 @@ struct vsp1_device {
> > > void __iomem *mmio;
> > > struct rcar_fcp_device *fcp;
> > > struct device *bus_master;
> > > + struct reset_control *rstc;
> > >
> > > struct vsp1_brx *brs;
> > > struct vsp1_brx *bru;
> > > diff --git a/drivers/media/platform/renesas/vsp1/vsp1_drv.c
> > > b/drivers/media/platform/renesas/vsp1/vsp1_drv.c
> > > index 1f73c48eb738..975e6851735e 100644
> > > --- a/drivers/media/platform/renesas/vsp1/vsp1_drv.c
> > > +++ b/drivers/media/platform/renesas/vsp1/vsp1_drv.c
> > > @@ -16,6 +16,7 @@
> > > #include <linux/of_device.h>
> > > #include <linux/platform_device.h>
> > > #include <linux/pm_runtime.h>
> > > +#include <linux/reset.h>
> > > #include <linux/videodev2.h>
> > >
> > > #include <media/rcar-fcp.h>
> > > @@ -622,6 +623,7 @@ static int __maybe_unused vsp1_pm_runtime_suspend(struct device *dev)
> > > struct vsp1_device *vsp1 = dev_get_drvdata(dev);
> > >
> > > rcar_fcp_disable(vsp1->fcp);
> > > + reset_control_assert(vsp1->rstc);
> > >
> > > return 0;
> > > }
> > > @@ -631,13 +633,30 @@ static int __maybe_unused vsp1_pm_runtime_resume(struct device *dev)
> > > struct vsp1_device *vsp1 = dev_get_drvdata(dev);
> > > int ret;
> > >
> > > + ret = reset_control_deassert(vsp1->rstc);
> > > + if (ret < 0)
> > > + return ret;
> > > +
> > > + /*
> > > + * On R-Car Gen2, vsp1 register access after deassert can cause
> > > + * lock-up. It is a special case and needs some delay to avoid
> > > + * this lock-up.
> >
> > You can reflow this to 80 columns:
> >
> > * On R-Car Gen2, vsp1 register access after deassert can cause lock-up.
> > * It is a special case and needs some delay to avoid this lock-up.
> >
> > > + */
>
> OK, but after adding conditional check for Gen2, it will look like [1]
>
> > > + udelay(1);
> >
> > Is it worth conditioning this on the VSP version to only add the delay
> > on Gen2 ?
>
> Will fix this in next version like [1], if it is Ok to everyone.
Works for me.
> > With these two small issues addressed,
>
> [1]
> if (vsp1->info) {
> 70 + /*
> 71 + * On R-Car Gen2 and RZ/G1, vsp1 register access after deassert
> 72 + * can cause lock-up.
> 73 + * It is a special case and needs some delay to avoid this
> 74 + * lock-up.
As a general rule, flow the text with sentence following each others
without line breaks, all the way to 80 columns. You can break a comment
in paragraphs, and there should then be a blank line between paragraphs.
You can thus write
* On R-Car Gen2 and RZ/G1, vsp1 register access after deassert
* can cause lock-up.
*
* It is a special case and needs some delay to avoid this
* lock-up.
or
* On R-Car Gen2 and RZ/G1, vsp1 register access after deassert
* can cause lock-up. It is a special case and needs some delay
* to avoid this lock-up.
but not
* On R-Car Gen2 and RZ/G1, vsp1 register access after deassert
* can cause lock-up.
* It is a special case and needs some delay to avoid this
* lock-up.
(I think the second option is better here)
> 75 + */
> 76 + if (vsp1->info->gen == 2)
> 77 + udelay(1);
>
> > Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> >
> > > +
> > > if (vsp1->info) {
> > > ret = vsp1_device_init(vsp1);
> > > if (ret < 0)
> > > - return ret;
> > > + goto done;
> > > }
> > >
> > > - return rcar_fcp_enable(vsp1->fcp);
> > > + ret = rcar_fcp_enable(vsp1->fcp);
> > > +
> > > +done:
> > > + if (ret < 0)
> > > + reset_control_assert(vsp1->rstc);
> > > +
> > > + return ret;
> > > }
> > >
> > > static const struct dev_pm_ops vsp1_pm_ops = { @@ -825,6 +844,11 @@
> > > static int vsp1_probe(struct platform_device *pdev)
> > > if (irq < 0)
> > > return irq;
> > >
> > > + vsp1->rstc = devm_reset_control_get_shared(&pdev->dev, NULL);
> > > + if (IS_ERR(vsp1->rstc))
> > > + return dev_err_probe(&pdev->dev, PTR_ERR(vsp1->rstc),
> > > + "failed to get reset control\n");
> > > +
> > > /* FCP (optional). */
> > > fcp_node = of_parse_phandle(pdev->dev.of_node, "renesas,fcp", 0);
--
Regards,
Laurent Pinchart
