* [PATCH] ARC: HSDK: improve reset driver
@ 2018-08-27 14:38 Eugeniy Paltsev
2018-09-11 15:25 ` Eugeniy Paltsev
2018-09-14 10:38 ` Philipp Zabel
0 siblings, 2 replies; 4+ messages in thread
From: Eugeniy Paltsev @ 2018-08-27 14:38 UTC (permalink / raw)
To: Philipp Zabel
Cc: linux-snps-arc, linux-kernel, Alexey Brodkin, Eugeniy Paltsev
As for today HSDK reset driver implements only
.reset() callback.
In case of driver which implements one of standard
reset controller usage pattern
(call *_deassert() in probe(), call *_assert() in remove())
that leads to inoperability of this reset driver.
Improve HSDK reset driver by calling .reset() callback inside of
.assert()/.deassert() callbacks to avoid each reset controller
user adaptation for work with both reset methods
(reset() and .assert()/.deassert() pair)
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
---
drivers/reset/reset-hsdk.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/reset/reset-hsdk.c b/drivers/reset/reset-hsdk.c
index 8bce391c6943..1fd91df91343 100644
--- a/drivers/reset/reset-hsdk.c
+++ b/drivers/reset/reset-hsdk.c
@@ -86,6 +86,8 @@ static int hsdk_reset_reset(struct reset_controller_dev *rcdev,
static const struct reset_control_ops hsdk_reset_ops = {
.reset = hsdk_reset_reset,
+ .assert = hsdk_reset_reset,
+ .deassert = hsdk_reset_reset,
};
static int hsdk_reset_probe(struct platform_device *pdev)
--
2.14.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] ARC: HSDK: improve reset driver
2018-08-27 14:38 [PATCH] ARC: HSDK: improve reset driver Eugeniy Paltsev
@ 2018-09-11 15:25 ` Eugeniy Paltsev
2018-09-14 10:38 ` Philipp Zabel
1 sibling, 0 replies; 4+ messages in thread
From: Eugeniy Paltsev @ 2018-09-11 15:25 UTC (permalink / raw)
To: p.zabel; +Cc: linux-kernel, Alexey Brodkin, linux-snps-arc
Hi Philipp,
Maybe you have any comments or remarks about this patch? And if you don't could you please apply it.
Thanks!
On Mon, 2018-08-27 at 17:38 +0300, Eugeniy Paltsev wrote:
> As for today HSDK reset driver implements only
> .reset() callback.
>
> In case of driver which implements one of standard
> reset controller usage pattern
> (call *_deassert() in probe(), call *_assert() in remove())
> that leads to inoperability of this reset driver.
>
> Improve HSDK reset driver by calling .reset() callback inside of
> .assert()/.deassert() callbacks to avoid each reset controller
> user adaptation for work with both reset methods
> (reset() and .assert()/.deassert() pair)
>
> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
> ---
> drivers/reset/reset-hsdk.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/reset/reset-hsdk.c b/drivers/reset/reset-hsdk.c
> index 8bce391c6943..1fd91df91343 100644
> --- a/drivers/reset/reset-hsdk.c
> +++ b/drivers/reset/reset-hsdk.c
> @@ -86,6 +86,8 @@ static int hsdk_reset_reset(struct reset_controller_dev *rcdev,
>
> static const struct reset_control_ops hsdk_reset_ops = {
> .reset = hsdk_reset_reset,
> + .assert = hsdk_reset_reset,
> + .deassert = hsdk_reset_reset,
> };
>
> static int hsdk_reset_probe(struct platform_device *pdev)
--
Eugeniy Paltsev
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] ARC: HSDK: improve reset driver
2018-08-27 14:38 [PATCH] ARC: HSDK: improve reset driver Eugeniy Paltsev
2018-09-11 15:25 ` Eugeniy Paltsev
@ 2018-09-14 10:38 ` Philipp Zabel
2018-09-24 11:08 ` Eugeniy Paltsev
1 sibling, 1 reply; 4+ messages in thread
From: Philipp Zabel @ 2018-09-14 10:38 UTC (permalink / raw)
To: Eugeniy Paltsev; +Cc: linux-snps-arc, linux-kernel, Alexey Brodkin
Hi Eugeniy,
On Mon, 2018-08-27 at 17:38 +0300, Eugeniy Paltsev wrote:
> As for today HSDK reset driver implements only
> .reset() callback.
>
> In case of driver which implements one of standard
> reset controller usage pattern
> (call *_deassert() in probe(), call *_assert() in remove())
> that leads to inoperability of this reset driver.
>
> Improve HSDK reset driver by calling .reset() callback inside of
> .assert()/.deassert() callbacks to avoid each reset controller
> user adaptation for work with both reset methods
> (reset() and .assert()/.deassert() pair)
>
> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
> ---
> drivers/reset/reset-hsdk.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/reset/reset-hsdk.c b/drivers/reset/reset-hsdk.c
> index 8bce391c6943..1fd91df91343 100644
> --- a/drivers/reset/reset-hsdk.c
> +++ b/drivers/reset/reset-hsdk.c
> @@ -86,6 +86,8 @@ static int hsdk_reset_reset(struct reset_controller_dev *rcdev,
>
> static const struct reset_control_ops hsdk_reset_ops = {
> .reset = hsdk_reset_reset,
> + .assert = hsdk_reset_reset,
This is incorrect for exclusive reset controls.
It will cause reset_control_assert() to return success for exclusive
reset controls, even though the .assert op failed to leave the reset
line asserted after the function returns.
While calling hsdk_reset_reset from .assert for shared reset controls
would be fine, I don't see how this is necessary of useful.
If a consumer driver requires the reset to be asserted upon remove(), it
must not request a shared reset control anyway, because with shared
reset controls other drivers may keep the reset line deasserted
indefinitely.
> + .deassert = hsdk_reset_reset,
This should be fine. I wonder from time to time whether this should be
implemented in the core, in reset_control_deassert().
regards
Philipp
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] ARC: HSDK: improve reset driver
2018-09-14 10:38 ` Philipp Zabel
@ 2018-09-24 11:08 ` Eugeniy Paltsev
0 siblings, 0 replies; 4+ messages in thread
From: Eugeniy Paltsev @ 2018-09-24 11:08 UTC (permalink / raw)
To: p.zabel, Eugeniy.Paltsev; +Cc: linux-kernel, Alexey.Brodkin, linux-snps-arc
Hi Philip,
On Fri, 2018-09-14 at 12:38 +0200, Philipp Zabel wrote:
> Hi Eugeniy,
>
> On Mon, 2018-08-27 at 17:38 +0300, Eugeniy Paltsev wrote:
> > As for today HSDK reset driver implements only
> > .reset() callback.
> >
> > In case of driver which implements one of standard
> > reset controller usage pattern
> > (call *_deassert() in probe(), call *_assert() in remove())
> > that leads to inoperability of this reset driver.
> >
> > Improve HSDK reset driver by calling .reset() callback inside of
> > .assert()/.deassert() callbacks to avoid each reset controller
> > user adaptation for work with both reset methods
> > (reset() and .assert()/.deassert() pair)
> >
> > Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
> > ---
> > drivers/reset/reset-hsdk.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/reset/reset-hsdk.c b/drivers/reset/reset-hsdk.c
> > index 8bce391c6943..1fd91df91343 100644
> > --- a/drivers/reset/reset-hsdk.c
> > +++ b/drivers/reset/reset-hsdk.c
> > @@ -86,6 +86,8 @@ static int hsdk_reset_reset(struct reset_controller_dev *rcdev,
> >
> > static const struct reset_control_ops hsdk_reset_ops = {
> > .reset = hsdk_reset_reset,
> > + = hsdk_reset_reset,
>
> This is incorrect for exclusive reset controls.
> It will cause reset_control_assert() to return success for exclusive
> reset controls, even though the .assert op failed to leave the reset
> line asserted after the function returns.
>
> While calling hsdk_reset_reset from .assert for shared reset controls
> would be fine, I don't see how this is necessary of useful.
> If a consumer driver requires the reset to be asserted upon remove(), it
> must not request a shared reset control anyway, because with shared
> reset controls other drivers may keep the reset line deasserted
> indefinitely.
Ok, I agree that doing reset from .assert isn't necessary/useful here.
The reason I added hsdk_reset_reset into .assert is to prevent -ENOTSUPP
returning by reset_control_assert().
Lots of drivers implement following pattern to reset HW:
------------------------->8------------------------------
reset_control_assert(resets);
usleep_range(10, 1000);
reset_control_deassert(resets);
------------------------->8------------------------------
And some of them check reset_control_assert() and reset_control_deassert()
return status.
So these driver will fail if I implement only .reset and .deassert callback in my
reset driver.
I can implement something like that:
------------------------->8------------------------------
static int hsdk_dummy_assert(struct reset_controller_dev *rd, unsigned long id)
{
return 0;
}
static const struct reset_control_ops hsdk_reset_ops = {
.reset = hsdk_reset_reset,
.assert = hsdk_dummy_assert,
.deassert = hsdk_reset_reset,
};
------------------------->8------------------------------
> > + .deassert = hsdk_reset_reset,
>
> This should be fine.
> I wonder from time to time whether this should be
> implemented in the core, in reset_control_deassert().
Sounds OK for me. At least I don't see any issues it may cause.
> regards
> Philipp
--
Eugeniy Paltsev
^ permalink raw reply [flat|nested] 4+ messages in thread
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2018-08-27 14:38 [PATCH] ARC: HSDK: improve reset driver Eugeniy Paltsev
2018-09-11 15:25 ` Eugeniy Paltsev
2018-09-14 10:38 ` Philipp Zabel
2018-09-24 11:08 ` Eugeniy Paltsev
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