Re: GPMI iMX6ull timeout on DMA

[Michael Nazzareno Trimarchi <michael@amarulasolutions.com>]

Hi


On Mon, Oct 18, 2021 at 9:19 AM Miquel Raynal <miquel.raynal@bootlin.com> wrote:
>
> Hi Michael,
>
> michael@amarulasolutions.com wrote on Fri, 15 Oct 2021 22:05:41 +0200:
>
> > Hi
> >
> > On Mon, Feb 01, 2021 at 04:14:33PM +0100, Miquel Raynal wrote:
> > > Hi Michael,
> > >
> > > Michael Nazzareno Trimarchi <michael@amarulasolutions.com> wrote on
> > > Mon, 1 Feb 2021 16:08:23 +0100:
> > >
> > > > Hi
> > > >
> > > > On Mon, Feb 1, 2021 at 3:32 PM Michael Nazzareno Trimarchi
> > > > <michael@amarulasolutions.com> wrote:
> > > > >
> > > > > Hi
> > > > >
> > > > > On Mon, Feb 1, 2021 at 3:13 PM Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> > > > > >
> > > > > > Hi Michael,
> > > > > >
> > > > > > Michael Nazzareno Trimarchi <michael@amarulasolutions.com> wrote on
> > > > > > Sat, 30 Jan 2021 10:41:29 +0100:
> > > > > >
> > > > > > > Hi Miquel
> > > > > > >
> > > > > > > commit f8e6ad14388067f91b26d044185d95623fbc9535
> > > > > > > Author: Michael Trimarchi <michael@amarulasolutions.com>
> > > > > > > Date:   Fri Jan 29 08:46:53 2021 +0100
> > > > > > >
> > > > > > >     mtd: nand: Calculate the clock before enable it
> > > > > > >
> > > > > > >     Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
> > > > > > >     Change-Id: I79b0da39de0a9b32ea0b002fa200d7f44d4f8ce7
> > > > > > >
> > > > > > > diff --git a/drivers/mtd/nand/raw/gpmi-nand/gpmi-lib.c
> > > > > > > b/drivers/mtd/nand/raw/gpmi-nand/gpmi-lib.c
> > > > > > > index 322a008290e5..0bca52b3bc8f 100644
> > > > > > > --- a/drivers/mtd/nand/raw/gpmi-nand/gpmi-lib.c
> > > > > > > +++ b/drivers/mtd/nand/raw/gpmi-nand/gpmi-lib.c
> > > > > > > @@ -377,6 +377,7 @@ static void gpmi_nfc_compute_timings(struct
> > > > > > > gpmi_nand_data *this,
> > > > > > >                                      const struct nand_sdr_timings *sdr)
> > > > > > >  {
> > > > > > >         struct gpmi_nfc_hardware_timing *hw = &this->hw;
> > > > > > > +       struct resources *r = &this->resources;
> > > > > > >         unsigned int dll_threshold_ps = this->devdata->max_chain_delay;
> > > > > > >         unsigned int period_ps, reference_period_ps;
> > > > > > >         unsigned int data_setup_cycles, data_hold_cycles, addr_setup_cycles;
> > > > > > > @@ -440,6 +441,8 @@ static void gpmi_nfc_compute_timings(struct
> > > > > > > gpmi_nand_data *this,
> > > > > > >                 hw->ctrl1n |= BF_GPMI_CTRL1_RDN_DELAY(sample_delay_factor) |
> > > > > > >                               BM_GPMI_CTRL1_DLL_ENABLE |
> > > > > > >                               (use_half_period ? BM_GPMI_CTRL1_HALF_PERIOD : 0);
> > > > > > > +
> > > > > > > +       clk_set_rate(r->clock[0], hw->clk_rate);
> > > > > > >  }
> > > > > > >
> > > > > > >  void gpmi_nfc_apply_timings(struct gpmi_nand_data *this)
> > > > > > > @@ -449,8 +452,6 @@ void gpmi_nfc_apply_timings(struct gpmi_nand_data *this)
> > > > > > >         void __iomem *gpmi_regs = r->gpmi_regs;
> > > > > > >         unsigned int dll_wait_time_us;
> > > > > > >
> > > > > > > -       clk_set_rate(r->clock[0], hw->clk_rate);
> > > > > > > -
> > > > > > >         writel(hw->timing0, gpmi_regs + HW_GPMI_TIMING0);
> > > > > > >         writel(hw->timing1, gpmi_regs + HW_GPMI_TIMING1);
> > > > > > >
> > > > > > > Right now I have this change applied and seems fine. That is the only
> > > > > > > difference I get. Clock is apply a bit earlier that when is enabled
> > > > > > > it.
> > > > > >
> > > > > > This is very interesting. So this would mean the issue you are
> > > > > > experiencing comes from the clock driver which kind of returns too
> > > > > > early from clk_set_rate()? Could you report this to the clk ML/NXP clk
> > > > > > maintainers and keep us in copy? If it is as global as it sounds, we
> > > > > > might not be the only ones affected.
> > > > > >
> > > > >
> > > > > The imx28 is broken too, so it's a general problem. I need to trace it down
> > > > > I have a reverting for lts but it\s not the way to go
> > > > >
> > > >
> > > > For imx28 you ask to set the rate to 22Mhz but you don't care about the clock
> > > > that you get back. You get back 12Mhz because the base clock is 24 Mhz and seems
> > > > that it can not get the point. You need to check if the clock
> > > > requested is in range or ask
> > > > for set_rate_clk_min to avoid to have somenthing lower. Then for
> > > > imx6ull because is sporadic
> > > > I think that is more connected to the clk_set_rate and when you change
> > > > the register. Can not be a
> > > > setting time?
> > >
> > > So, if I understand correctly, we face two different problems:
> > > - imx6*: seems like a clock issue regarding the clock settlement
> > > - imx28: actual NAND driver issue (does not check the validity of the
> > >   new frequency). This should be handled properly in
> > >   ->setup_interface().
> > >
> >
> > Somenthing like this? Not compile/tested
> >
> > diff --git a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> > index 4d08e4ab5c1b..cc8146ab1b78 100644
> > --- a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> > +++ b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> > @@ -644,7 +644,7 @@ static int bch_set_geometry(struct gpmi_nand_data *this)
> >   *         RDN_DELAY = -----------------------     {3}
> >   *                           RP
> >   */
> > -static void gpmi_nfc_compute_timings(struct gpmi_nand_data *this,
> > +static int gpmi_nfc_compute_timings(struct gpmi_nand_data *this,
> >                                    const struct nand_sdr_timings *sdr)
> >  {
> >       struct gpmi_nfc_hardware_timing *hw = &this->hw;
> > @@ -656,6 +656,7 @@ static void gpmi_nfc_compute_timings(struct gpmi_nand_data *this,
> >       int sample_delay_ps, sample_delay_factor;
> >       u16 busy_timeout_cycles;
> >       u8 wrn_dly_sel;
> > +     long clk_rate;
> >
> >       if (sdr->tRC_min >= 30000) {
> >               /* ONFI non-EDO modes [0-3] */
> > @@ -671,6 +672,10 @@ static void gpmi_nfc_compute_timings(struct gpmi_nand_data *this,
> >               wrn_dly_sel = BV_GPMI_CTRL1_WRN_DLY_SEL_NO_DELAY;
> >       }
> >
> > +     clk_rate = clk_round_rate(r->clock[0], hw->clk_rate);
> > +     if (clk_rate < hw->clk_rate || clk_rate <= 0)
> > +             return -ENOTSUPP;
>
> I believe clk_rate < hw->clk_rate will always match cases where
> clk_rate <= 0 ?
>
> The check looks very strict though. Will it even pass on i.MX6? Perhaps
> we could verify something like a 10% error which might grab all the
> erroneous situations?

According to what I read the clk is the min that we can accept. So any clock
from EDO4 to EDO5 should be ok. My concern is that calculation. I need to read
it properly. I don't think that put 10% or any will help us, until we
now that is possible or not.

I will even anyway put a warning

Michael

>
>         if (abs(clk_rate - hw->clk_rate) > (hw->clk_rate / 10))
>                 return -ENOTSUPP;
>
> > +
> >       /* SDR core timings are given in picoseconds */
> >       period_ps = div_u64((u64)NSEC_PER_SEC * 1000, hw->clk_rate);
> >
> > @@ -746,6 +751,7 @@ static int gpmi_setup_interface(struct nand_chip *chip, int chipnr,
> >  {
> >       struct gpmi_nand_data *this = nand_get_controller_data(chip);
> >       const struct nand_sdr_timings *sdr;
> > +     int ret = 0;
> >
> >       /* Retrieve required NAND timings */
> >       sdr = nand_get_sdr_timings(conf);
> > @@ -761,11 +767,11 @@ static int gpmi_setup_interface(struct nand_chip *chip, int chipnr,
> >               return 0;
> >
> >       /* Do the actual derivation of the controller timings */
> > -     gpmi_nfc_compute_timings(this, sdr);
> > -
> > -     this->hw.must_apply_timings = true;
> > +     ret = gpmi_nfc_compute_timings(this, sdr);
> > +     if (!ret)
> > +             this->hw.must_apply_timings = true;
> >
> > -     return 0;
> > +     return ret;
> >  }
> >
> >  /* Clears a BCH interrupt. */
> > > Thanks,
> > > Miquèl
>
> Otherwise looks good, thanks!
>
> Miquèl



--
Michael Nazzareno Trimarchi
Co-Founder & Chief Executive Officer
M. +39 347 913 2170
michael@amarulasolutions.com
__________________________________

Amarula Solutions BV
Joop Geesinkweg 125, 1114 AB, Amsterdam, NL
T. +31 (0)85 111 9172
info@amarulasolutions.com
www.amarulasolutions.com

______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/