* Re: [PATCH 2/2] mtd: nand: sunxi: add reset line support
[not found] ` <20160619113739.30362-2-icenowy@aosc.xyz>
@ 2016-06-19 12:06 ` Boris Brezillon
[not found] ` <2686901466340069@web27g.yandex.ru>
2016-06-20 12:05 ` Philipp Zabel
0 siblings, 2 replies; 5+ messages in thread
From: Boris Brezillon @ 2016-06-19 12:06 UTC (permalink / raw)
To: Icenowy Zheng
Cc: maxime.ripard, wens, robh+dt, richard, dwmw2, computersforpeace,
devicetree, linux-kernel, linux-mtd, linux-sunxi, Philipp Zabel
+Philipp
On Sun, 19 Jun 2016 19:37:39 +0800
Icenowy Zheng <icenowy@aosc.xyz> wrote:
> The NAND controller on some sun8i chips needs its reset line to be deasserted
> before they can enter working state. This commit added the reset line process
> to the driver.
>
> Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>
> ---
> drivers/mtd/nand/sunxi_nand.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
> index a83a690..1502748 100644
> --- a/drivers/mtd/nand/sunxi_nand.c
> +++ b/drivers/mtd/nand/sunxi_nand.c
> @@ -39,6 +39,7 @@
> #include <linux/gpio.h>
> #include <linux/interrupt.h>
> #include <linux/iopoll.h>
> +#include <linux/reset.h>
>
> #define NFC_REG_CTL 0x0000
> #define NFC_REG_ST 0x0004
> @@ -269,6 +270,7 @@ struct sunxi_nfc {
> void __iomem *regs;
> struct clk *ahb_clk;
> struct clk *mod_clk;
> + struct reset_control *reset;
> unsigned long assigned_cs;
> unsigned long clk_rate;
> struct list_head chips;
> @@ -1871,6 +1873,18 @@ static int sunxi_nfc_probe(struct platform_device *pdev)
> if (ret)
> goto out_ahb_clk_unprepare;
>
> + nfc->reset = devm_reset_control_get_optional(dev, "ahb");
> + if (PTR_ERR(nfc->reset) == -EPROBE_DEFER)
> + return PTR_ERR(nfc->reset);
Actually you should test for != -ENOENT, because all error codes except
this one should stop the ->probe().
BTW, this devm_reset_control_get_optional() is really weird. While most
_optional() methods return NULL when the element is not defined in the
DT, this one returns -ENOTENT, which makes it impossible to
differentiate a real error from a undefined reset line (which is a
valid case for _optional()).
Philipp, is there a good reason for doing that?
> +
> + if (!IS_ERR(nfc->reset)) {
> + ret = reset_control_deassert(nfc->reset);
> + if (ret) {
> + dev_err(dev, "reset err %d\n", ret);
> + goto out_mod_clk_unprepare;
> + }
> + }
> +
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2] mtd: nand: sunxi: add reset line support
[not found] ` <2686901466340069@web27g.yandex.ru>
@ 2016-06-19 12:53 ` Boris Brezillon
[not found] ` <2748041466341860@web7m.yandex.ru>
0 siblings, 1 reply; 5+ messages in thread
From: Boris Brezillon @ 2016-06-19 12:53 UTC (permalink / raw)
To: icenowy
Cc: maxime.ripard, wens, robh+dt, richard, dwmw2, computersforpeace,
devicetree, linux-kernel, linux-mtd, linux-sunxi, Philipp Zabel
On Sun, 19 Jun 2016 20:41:09 +0800
icenowy@aosc.xyz wrote:
> To be honest, I copied them from sunxi-mmc.c.
>
> What function should be chosen better?
You did the right thing (except for the error detection part). My
question was addressed to Philipp (the reset subsystem maintainer).
>
>
> 19.06.2016, 20:06, "Boris Brezillon" <boris.brezillon@free-electrons.com>:
> > +Philipp
> >
> > On Sun, 19 Jun 2016 19:37:39 +0800
> > Icenowy Zheng <icenowy@aosc.xyz> wrote:
> >
> >> The NAND controller on some sun8i chips needs its reset line to be deasserted
> >> before they can enter working state. This commit added the reset line process
> >> to the driver.
> >>
> >> Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>
> >> ---
> >> drivers/mtd/nand/sunxi_nand.c | 14 ++++++++++++++
> >> 1 file changed, 14 insertions(+)
> >>
> >> diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
> >> index a83a690..1502748 100644
> >> --- a/drivers/mtd/nand/sunxi_nand.c
> >> +++ b/drivers/mtd/nand/sunxi_nand.c
> >> @@ -39,6 +39,7 @@
> >> #include <linux/gpio.h>
> >> #include <linux/interrupt.h>
> >> #include <linux/iopoll.h>
> >> +#include <linux/reset.h>
> >>
> >> #define NFC_REG_CTL 0x0000
> >> #define NFC_REG_ST 0x0004
> >> @@ -269,6 +270,7 @@ struct sunxi_nfc {
> >> void __iomem *regs;
> >> struct clk *ahb_clk;
> >> struct clk *mod_clk;
> >> + struct reset_control *reset;
> >> unsigned long assigned_cs;
> >> unsigned long clk_rate;
> >> struct list_head chips;
> >> @@ -1871,6 +1873,18 @@ static int sunxi_nfc_probe(struct platform_device *pdev)
> >> if (ret)
> >> goto out_ahb_clk_unprepare;
> >>
> >> + nfc->reset = devm_reset_control_get_optional(dev, "ahb");
> >> + if (PTR_ERR(nfc->reset) == -EPROBE_DEFER)
> >> + return PTR_ERR(nfc->reset);
> >
> > Actually you should test for != -ENOENT, because all error codes except
> > this one should stop the ->probe().
> >
> > BTW, this devm_reset_control_get_optional() is really weird. While most
> > _optional() methods return NULL when the element is not defined in the
> > DT, this one returns -ENOTENT, which makes it impossible to
> > differentiate a real error from a undefined reset line (which is a
> > valid case for _optional()).
> >
> > Philipp, is there a good reason for doing that?
> >
> >> +
> >> + if (!IS_ERR(nfc->reset)) {
> >> + ret = reset_control_deassert(nfc->reset);
> >> + if (ret) {
> >> + dev_err(dev, "reset err %d\n", ret);
> >> + goto out_mod_clk_unprepare;
> >> + }
> >> + }
> >> +
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2] mtd: nand: sunxi: add reset line support
[not found] ` <2748041466341860@web7m.yandex.ru>
@ 2016-06-19 13:16 ` Boris Brezillon
0 siblings, 0 replies; 5+ messages in thread
From: Boris Brezillon @ 2016-06-19 13:16 UTC (permalink / raw)
To: icenowy
Cc: maxime.ripard, wens, robh+dt, richard, dwmw2, computersforpeace,
devicetree, linux-kernel, linux-mtd, linux-sunxi, Philipp Zabel
On Sun, 19 Jun 2016 21:11:00 +0800
icenowy@aosc.xyz wrote:
> Then I will soon make the v2 patch set, with the error detection part fixed.
>
> But why does sunxi-mmc check only EPROBE_DEFER?
I guess someone had a probe-dependency problem and fixed this case but
ignored all the possible errors. But there may be other reasons for
devm_reset_control_get_optional() to fail. The only one that is really
reflecting that the reset line is not defined in the DT is -ENOENT.
>
> 19.06.2016, 20:53, "Boris Brezillon" <boris.brezillon@free-electrons.com>:
> > On Sun, 19 Jun 2016 20:41:09 +0800
> > icenowy@aosc.xyz wrote:
> >
> >> To be honest, I copied them from sunxi-mmc.c.
> >>
> >> What function should be chosen better?
> >
> > You did the right thing (except for the error detection part). My
> > question was addressed to Philipp (the reset subsystem maintainer).
> >
> >> 19.06.2016, 20:06, "Boris Brezillon" <boris.brezillon@free-electrons.com>:
> >> > +Philipp
> >> >
> >> > On Sun, 19 Jun 2016 19:37:39 +0800
> >> > Icenowy Zheng <icenowy@aosc.xyz> wrote:
> >> >
> >> >> The NAND controller on some sun8i chips needs its reset line to be deasserted
> >> >> before they can enter working state. This commit added the reset line process
> >> >> to the driver.
> >> >>
> >> >> Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>
> >> >> ---
> >> >> drivers/mtd/nand/sunxi_nand.c | 14 ++++++++++++++
> >> >> 1 file changed, 14 insertions(+)
> >> >>
> >> >> diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
> >> >> index a83a690..1502748 100644
> >> >> --- a/drivers/mtd/nand/sunxi_nand.c
> >> >> +++ b/drivers/mtd/nand/sunxi_nand.c
> >> >> @@ -39,6 +39,7 @@
> >> >> #include <linux/gpio.h>
> >> >> #include <linux/interrupt.h>
> >> >> #include <linux/iopoll.h>
> >> >> +#include <linux/reset.h>
> >> >>
> >> >> #define NFC_REG_CTL 0x0000
> >> >> #define NFC_REG_ST 0x0004
> >> >> @@ -269,6 +270,7 @@ struct sunxi_nfc {
> >> >> void __iomem *regs;
> >> >> struct clk *ahb_clk;
> >> >> struct clk *mod_clk;
> >> >> + struct reset_control *reset;
> >> >> unsigned long assigned_cs;
> >> >> unsigned long clk_rate;
> >> >> struct list_head chips;
> >> >> @@ -1871,6 +1873,18 @@ static int sunxi_nfc_probe(struct platform_device *pdev)
> >> >> if (ret)
> >> >> goto out_ahb_clk_unprepare;
> >> >>
> >> >> + nfc->reset = devm_reset_control_get_optional(dev, "ahb");
> >> >> + if (PTR_ERR(nfc->reset) == -EPROBE_DEFER)
> >> >> + return PTR_ERR(nfc->reset);
> >> >
> >> > Actually you should test for != -ENOENT, because all error codes except
> >> > this one should stop the ->probe().
> >> >
> >> > BTW, this devm_reset_control_get_optional() is really weird. While most
> >> > _optional() methods return NULL when the element is not defined in the
> >> > DT, this one returns -ENOTENT, which makes it impossible to
> >> > differentiate a real error from a undefined reset line (which is a
> >> > valid case for _optional()).
> >> >
> >> > Philipp, is there a good reason for doing that?
> >> >
> >> >> +
> >> >> + if (!IS_ERR(nfc->reset)) {
> >> >> + ret = reset_control_deassert(nfc->reset);
> >> >> + if (ret) {
> >> >> + dev_err(dev, "reset err %d\n", ret);
> >> >> + goto out_mod_clk_unprepare;
> >> >> + }
> >> >> + }
> >> >> +
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2] mtd: nand: sunxi: add reset line support
2016-06-19 12:06 ` [PATCH 2/2] mtd: nand: sunxi: add reset line support Boris Brezillon
[not found] ` <2686901466340069@web27g.yandex.ru>
@ 2016-06-20 12:05 ` Philipp Zabel
2016-06-20 12:51 ` Boris Brezillon
1 sibling, 1 reply; 5+ messages in thread
From: Philipp Zabel @ 2016-06-20 12:05 UTC (permalink / raw)
To: Boris Brezillon
Cc: Icenowy Zheng, maxime.ripard, wens, robh+dt, richard, dwmw2,
computersforpeace, devicetree, linux-kernel, linux-mtd,
linux-sunxi
Am Sonntag, den 19.06.2016, 14:06 +0200 schrieb Boris Brezillon:
> +Philipp
>
> On Sun, 19 Jun 2016 19:37:39 +0800
> Icenowy Zheng <icenowy@aosc.xyz> wrote:
>
> > The NAND controller on some sun8i chips needs its reset line to be deasserted
> > before they can enter working state. This commit added the reset line process
> > to the driver.
> >
> > Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>
> > ---
> > drivers/mtd/nand/sunxi_nand.c | 14 ++++++++++++++
> > 1 file changed, 14 insertions(+)
> >
> > diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
> > index a83a690..1502748 100644
> > --- a/drivers/mtd/nand/sunxi_nand.c
> > +++ b/drivers/mtd/nand/sunxi_nand.c
> > @@ -39,6 +39,7 @@
> > #include <linux/gpio.h>
> > #include <linux/interrupt.h>
> > #include <linux/iopoll.h>
> > +#include <linux/reset.h>
> >
> > #define NFC_REG_CTL 0x0000
> > #define NFC_REG_ST 0x0004
> > @@ -269,6 +270,7 @@ struct sunxi_nfc {
> > void __iomem *regs;
> > struct clk *ahb_clk;
> > struct clk *mod_clk;
> > + struct reset_control *reset;
> > unsigned long assigned_cs;
> > unsigned long clk_rate;
> > struct list_head chips;
> > @@ -1871,6 +1873,18 @@ static int sunxi_nfc_probe(struct platform_device *pdev)
> > if (ret)
> > goto out_ahb_clk_unprepare;
> >
> > + nfc->reset = devm_reset_control_get_optional(dev, "ahb");
> > + if (PTR_ERR(nfc->reset) == -EPROBE_DEFER)
> > + return PTR_ERR(nfc->reset);
>
> Actually you should test for != -ENOENT, because all error codes except
> this one should stop the ->probe().
>
> BTW, this devm_reset_control_get_optional() is really weird. While most
> _optional() methods return NULL when the element is not defined in the
> DT, this one returns -ENOTENT, which makes it impossible to
> differentiate a real error from a undefined reset line (which is a
> valid case for _optional()).
Of course it's possible, -ENOENT is only returned if the reset line is
not defined in the device tree.
Note that gpiod_get_(index_)optional do nothing more that replacing
-ENOENT with NULL. And phydev_optional_get replaces -ENODEV with NULL.
And regulator_get_optional, if I understand it correctly, never returns
NULL.
> Philipp, is there a good reason for doing that?
Historically, NULL has not been a valid value for rstc. I suppose we
could add NULL checks to the reset_control_assert/deassert/reset/status
functions and align the reset API a bit with gpiod. I just wouldn't want
to see any IS_ERR_OR_NULL error handling in the drivers.
regards
Philipp
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 2/2] mtd: nand: sunxi: add reset line support
2016-06-20 12:05 ` Philipp Zabel
@ 2016-06-20 12:51 ` Boris Brezillon
0 siblings, 0 replies; 5+ messages in thread
From: Boris Brezillon @ 2016-06-20 12:51 UTC (permalink / raw)
To: Philipp Zabel
Cc: Icenowy Zheng, maxime.ripard, wens, robh+dt, richard, dwmw2,
computersforpeace, devicetree, linux-kernel, linux-mtd,
linux-sunxi
Hi Philipp,
On Mon, 20 Jun 2016 14:05:54 +0200
Philipp Zabel <p.zabel@pengutronix.de> wrote:
> Am Sonntag, den 19.06.2016, 14:06 +0200 schrieb Boris Brezillon:
> > +Philipp
> >
> > On Sun, 19 Jun 2016 19:37:39 +0800
> > Icenowy Zheng <icenowy@aosc.xyz> wrote:
> >
> > > The NAND controller on some sun8i chips needs its reset line to be deasserted
> > > before they can enter working state. This commit added the reset line process
> > > to the driver.
> > >
> > > Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>
> > > ---
> > > drivers/mtd/nand/sunxi_nand.c | 14 ++++++++++++++
> > > 1 file changed, 14 insertions(+)
> > >
> > > diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
> > > index a83a690..1502748 100644
> > > --- a/drivers/mtd/nand/sunxi_nand.c
> > > +++ b/drivers/mtd/nand/sunxi_nand.c
> > > @@ -39,6 +39,7 @@
> > > #include <linux/gpio.h>
> > > #include <linux/interrupt.h>
> > > #include <linux/iopoll.h>
> > > +#include <linux/reset.h>
> > >
> > > #define NFC_REG_CTL 0x0000
> > > #define NFC_REG_ST 0x0004
> > > @@ -269,6 +270,7 @@ struct sunxi_nfc {
> > > void __iomem *regs;
> > > struct clk *ahb_clk;
> > > struct clk *mod_clk;
> > > + struct reset_control *reset;
> > > unsigned long assigned_cs;
> > > unsigned long clk_rate;
> > > struct list_head chips;
> > > @@ -1871,6 +1873,18 @@ static int sunxi_nfc_probe(struct platform_device *pdev)
> > > if (ret)
> > > goto out_ahb_clk_unprepare;
> > >
> > > + nfc->reset = devm_reset_control_get_optional(dev, "ahb");
> > > + if (PTR_ERR(nfc->reset) == -EPROBE_DEFER)
> > > + return PTR_ERR(nfc->reset);
> >
> > Actually you should test for != -ENOENT, because all error codes except
> > this one should stop the ->probe().
> >
> > BTW, this devm_reset_control_get_optional() is really weird. While most
> > _optional() methods return NULL when the element is not defined in the
> > DT, this one returns -ENOTENT, which makes it impossible to
> > differentiate a real error from a undefined reset line (which is a
> > valid case for _optional()).
>
> Of course it's possible, -ENOENT is only returned if the reset line is
> not defined in the device tree.
Okay, testing for err != -ENOENT is the right thing to do here. Maybe
this could be documented.
>
> Note that gpiod_get_(index_)optional do nothing more that replacing
> -ENOENT with NULL. And phydev_optional_get replaces -ENODEV with NULL.
> And regulator_get_optional, if I understand it correctly, never returns
> NULL.
>
> > Philipp, is there a good reason for doing that?
>
> Historically, NULL has not been a valid value for rstc. I suppose we
> could add NULL checks to the reset_control_assert/deassert/reset/status
> functions and align the reset API a bit with gpiod. I just wouldn't want
> to see any IS_ERR_OR_NULL error handling in the drivers.
Well, returning NULL is mainly a convenient way to differentiate real
errors from missing optional reset lines (which are not errors). Now,
if you say checking for -ENOENT is the right thing to do here, I'm
fine with that.
Regards,
Boris
^ permalink raw reply [flat|nested] 5+ messages in thread
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2016-06-19 12:06 ` [PATCH 2/2] mtd: nand: sunxi: add reset line support Boris Brezillon
[not found] ` <2686901466340069@web27g.yandex.ru>
2016-06-19 12:53 ` Boris Brezillon
[not found] ` <2748041466341860@web7m.yandex.ru>
2016-06-19 13:16 ` Boris Brezillon
2016-06-20 12:05 ` Philipp Zabel
2016-06-20 12:51 ` Boris Brezillon
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