Assert DisplayPort reset signal before deasserting,
it is to clear out any registers programmed before booting kernel.
Signed-off-by: Rohit Visavalia <[email protected]>
---
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;
+
ret = zynqmp_dp_reset(dp, false);
if (ret < 0)
goto err_free;
--
2.25.1
[AMD Official Use Only - General]
Hi Rohit,
Thanks for the patch.
> -----Original Message-----
> From: dri-devel <[email protected]> On Behalf Of
> Rohit Visavalia
> Sent: Friday, February 16, 2024 1:41 PM
> To: [email protected]; [email protected];
> [email protected]; [email protected];
> [email protected]; [email protected]; [email protected]; Simek, Michal
> <[email protected]>; [email protected]; linux-arm-
> [email protected]
> Cc: [email protected]
> Subject: [PATCH] drm: xlnx: dp: Reset DisplayPort IP
>
> Assert DisplayPort reset signal before deasserting,
> it is to clear out any registers programmed before booting kernel.
>
> Signed-off-by: Rohit Visavalia <[email protected]>
> ---
> 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;
> +
> ret = zynqmp_dp_reset(dp, false);
> if (ret < 0)
> goto err_free;
> --
> 2.25.1
This looks good to me.
Reviewed-by: Vishal Sagar<[email protected]>
Regards
Vishal Sagar
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 <[email protected]>
> ---
> 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 <[email protected]>
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
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 <[email protected]>
> > ---
> > 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 <[email protected]>
>
> 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
On 29/02/2024 11:05, Laurent Pinchart wrote:
> 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 <[email protected]>
>>> ---
>>> 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 <[email protected]>
>>
Thanks, tested and pushed to drm-misc-next.
Tomi