Re: [PATCH v1] mtd: rawnand: meson: initialize clock register

[Liang Yang]

Hi Arseniy,

I remember that you asked it in another email, but i forgot to reply. Sorry

On 2023/11/12 18:08, Arseniy Krasnov wrote:
> [ EXTERNAL EMAIL ]
>
> On 09.11.2023 08:40, Arseniy Krasnov wrote:
> > Clock register must be also initialized during controller probing. If
> > this is not performed (for example by bootloader before) - controller
> > will not work.
> >
> > Signed-off-by: Arseniy Krasnov <avkrasnov@xxxxxxxxxxxxxxxxx>
> > ---
> >   drivers/mtd/nand/raw/meson_nand.c | 4 +++-
> >   1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
> > index 0d4d358152d7..4e7fa943928c 100644
> > --- a/drivers/mtd/nand/raw/meson_nand.c
> > +++ b/drivers/mtd/nand/raw/meson_nand.c
> > @@ -91,6 +91,8 @@
> >
> >   /* eMMC clock register, misc control */
> >   #define CLK_SELECT_NAND              BIT(31)
> > +#define CLK_ALWAYS_ON_NAND      BIT(24)
> > +#define CLK_ENABLE_VALUE        0x245
>                                     ^^^^^^
>
> Hi,
>
> @Liang, it will be great, if You'll give some details about this magic value. I get it
> from vendor's driver and it makes NAND controller alive, but I don't have any docs.


Bit 7:6 is used to select the clock source for NAND controller.
	00 : more clock source
	01 : fix pll is select, commonly 1GHZ in Amlogic soc chips.

The implementation in meson nfc driver should select '01', so you could 
do like this :
#define CLK_SELECT_FIX_PLL2		BIT(6)
writel(CLK_ALWAYS_ON_NAND | CLK_SELECT_NAND | CLK_SELECT_FIX_PLL2,
	 nfc->reg_clk);

Bit 5:0 is the clock divider.

> Thanks, Arseniy
>
> >   #define NFC_CLK_CYCLE                6
> >
> > @@ -1152,7 +1154,7 @@ static int meson_nfc_clk_init(struct meson_nfc *nfc)
> >                return PTR_ERR(nfc->nand_clk);
> >
> >        /* init SD_EMMC_CLOCK to sane defaults w/min clock rate */
> > -     writel(CLK_SELECT_NAND | readl(nfc->reg_clk),
> > +     writel(CLK_ALWAYS_ON_NAND | CLK_SELECT_NAND | CLK_ENABLE_VALUE,
> >               nfc->reg_clk);
> >
> >        ret = clk_prepare_enable(nfc->core_clk);

--
Thanks,
Liang