Hi Laurent,
Thanks for the feedback.
> Subject: Re: [PATCH v13 2/5] media: renesas: vsp1: Add support to
> deassert/assert reset line
>
> Hi Biju,
>
> Thank you for the patch.
>
> 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.
>
> 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.
75 + */
76 + if (vsp1->info->gen == 2)
77 + udelay(1);
Cheers,
Biju
>
> 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);
> > if (fcp_node) {
>
> --
> Regards,
>
> Laurent Pinchart
