On Sun, 19 Jun 2016 21:11:00 +0800
icenowy@xxxxxxxx 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@xxxxxxxxxxxxxxxxxx>:
> > On Sun, 19 Jun 2016 20:41:09 +0800
> > icenowy@xxxxxxxx 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@xxxxxxxxxxxxxxxxxx>:
> >> > +Philipp
> >> >
> >> > On Sun, 19 Jun 2016 19:37:39 +0800
> >> > Icenowy Zheng <icenowy@xxxxxxxx> 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@xxxxxxxx>
> >> >> ---
> >> >> 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;
> >> >> + }
> >> >> + }
> >> >> +
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
