Tomi, could you push this through drm-misc ?
On Wed, Feb 28, 2024 at 06:22:25PM +0200, Laurent Pinchart wrote:
> Hello Rohit,
>
> Thank you for the patch.
>
> On Fri, Feb 16, 2024 at 04:40:43AM -0800, Rohit Visavalia wrote:
> > Assert DisplayPort reset signal before deasserting,
> > it is to clear out any registers programmed before booting kernel.
> >
> > Signed-off-by: Rohit Visavalia <rohit.visavalia@xxxxxxx>
> > ---
> > drivers/gpu/drm/xlnx/zynqmp_dp.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c
> > index 1846c4971fd8..5a40aa1d4283 100644
> > --- a/drivers/gpu/drm/xlnx/zynqmp_dp.c
> > +++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c
> > @@ -1714,6 +1714,10 @@ int zynqmp_dp_probe(struct zynqmp_dpsub *dpsub)
> > goto err_free;
> > }
> >
> > + ret = zynqmp_dp_reset(dp, true);
> > + if (ret < 0)
> > + return ret;
> > +
>
> This looks fine to me, so
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
>
> However, looking at zynqmp_dp_reset(), we have
>
> static int zynqmp_dp_reset(struct zynqmp_dp *dp, bool assert)
> {
> unsigned long timeout;
>
> if (assert)
> reset_control_assert(dp->reset);
> else
> reset_control_deassert(dp->reset);
>
> /* Wait for the (de)assert to complete. */
> timeout = jiffies + msecs_to_jiffies(RST_TIMEOUT_MS);
> while (!time_after_eq(jiffies, timeout)) {
> bool status = !!reset_control_status(dp->reset);
>
> if (assert == status)
> return 0;
>
> cpu_relax();
> }
>
> dev_err(dp->dev, "reset %s timeout\n", assert ? "assert" : "deassert");
> return -ETIMEDOUT;
> }
>
> That doesn't seem quite right. Aren't reset_control_assert() and
> reset_control_deassert() supposed to be synchronous ? If so there should
> be no need to wait, and if there's a need to wait, it could be a bug in
> the reset controller driver. This should be fixed, and then the code in
> probe could be replaced with a call to reset_control_reset().
>
> > ret = zynqmp_dp_reset(dp, false);
> > if (ret < 0)
> > goto err_free;
--
Regards,
Laurent Pinchart
