[U-Boot] [PATCH] hikey: Take peripherals out of reset during board init

[Manivannan Sadhasivam]

Hi Peter,

On Tue, Mar 19, 2019 at 11:29:01AM +0000, Peter Griffin wrote:
> Hi Mani,
> 
> This looks like a bug in the Linux kernel. The kernel driver should be
> correctly
> handling the reset lines of the I2C or SPI peripheral rather than replying
> on
> the bootloader to have already taken it out of reset.
> 

Correct. After sending this patch out, I sent a patchset to LKML [1] for fixing
the issue in Linux kernel (thanks to Daniel for suggesting the change). But,
we might need this hack in u-boot to make the old kernel/dts to work properly.
And that's the reason I didn't abandon this patch.

Thanks,
Mani

[1] https://lkml.org/lkml/2019/3/8/878

> Peter.
> 
> On Fri, 8 Mar 2019 at 08:57, Manivannan Sadhasivam <
> manivannan.sadhasivam at linaro.org> wrote:
> 
> > Peripherals like I2C and SPI needs to be taken out of reset during
> > board init for functioning properly. Hence, add `hi6220_periph_reset`
> > function for doing the same. For instance without this function, I2C
> > will fail like below while booting linux:
> >
> > [    0.608033] i2c_designware f7100000.i2c: Unknown Synopsys component
> > type:
> > 0x00000000
> > [    0.621378] i2c_designware f7101000.i2c: Unknown Synopsys component
> > type:
> > 0x00000000
> > [    0.633818] i2c_designware f7102000.i2c: Unknown Synopsys component
> > type:
> > 0x00000000
> >
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam at linaro.org>
> > ---
> >  board/hisilicon/hikey/hikey.c | 16 ++++++++++++++++
> >  1 file changed, 16 insertions(+)
> >
> > diff --git a/board/hisilicon/hikey/hikey.c b/board/hisilicon/hikey/hikey.c
> > index 940ae82c45b..f8b8c372bfd 100644
> > --- a/board/hisilicon/hikey/hikey.c
> > +++ b/board/hisilicon/hikey/hikey.c
> > @@ -364,6 +364,20 @@ static void hi6220_pmussi_init(void)
> >         gpio_direction_output(0, 1);
> >  }
> >
> > +static void hi6220_periph_reset(void)
> > +{
> > +       u32 data, bits;
> > +
> > +       /* Bring I2C0/I2C1/I2C2/SPI0 out of reset */
> > +       bits = PERI_RST3_I2C0 | PERI_RST3_I2C1 | PERI_RST3_I2C2 |
> > PERI_RST3_SSP;
> > +       writel(bits, &peri_sc->rst3_dis);
> > +
> > +       /* Wait until the peripherals are out of reset */
> > +       do {
> > +               data = readl(&peri_sc->rst3_dis);
> > +       } while (data & bits);
> > +}
> > +
> >  int misc_init_r(void)
> >  {
> >         return 0;
> > @@ -371,6 +385,8 @@ int misc_init_r(void)
> >
> >  int board_init(void)
> >  {
> > +       hi6220_periph_reset();
> > +
> >         return 0;
> >  }
> >
> > --
> > 2.17.1
> >
> >