[PATCH 2/2] mtd: nand: sunxi: add reset line support

[icenowy at aosc.xyz]

To be honest, I copied them from sunxi-mmc.c.

What function should be chosen better?


19.06.2016, 20:06, "Boris Brezillon" <boris.brezillon at free-electrons.com>:
> +Philipp
>
> On Sun, 19 Jun 2016 19:37:39 +0800
> Icenowy Zheng <icenowy at 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 at 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;
>>  + }
>>  + }
>>  +